Fun with the Fast90

End of year breaks are nice. Especially when unseasonal weather is about. Usually its snowy and horrible. However this year its been quite fair. Yesterday was 13* and sunny, so I checked the forecast and hauled my tools out to the front of the house to start the Fast90 install.
As Id replaced the injectors before I thought that it would only take a few hours. Id done some reading and the swap and instructions that came with the manifold made it look easy..

Id done some blending of the internal edges and filled some gaps with epoxy, then sanded it all flat and smooth. Nothing major, just a cleanup.

Of course nothing quite goes to plan. Disassembly was easy as you can see below I still have the original LS1 coolant lines under the intake.

There are a few tricky connectors at the rear, but the Holden has reasonable clearance there. You can also lift the manifold forward a little to get better access to the MAP and brake booster line. I did a little cleanup around the intake ports to remove grime too.

Next I needed to remove the coolant lines and replace them with late model plugs and cross over. You can see faintly the rear engine mount on the left, this was to be a pain in the arse.

You also need to remove the clips on the knock sensor wires. I also took off the tape as it was thick and hard, pretty much the same size as the clips. Then replace the valley cover bolts with the button head ones like the pic above. This all helps get the manifold down snug as the floor is lower than stock.

Right time to fit the fast. Cool. Well no, not cool. The problem is that the Fast is longer than the stock manifold and the power steering tank is in the way, worse the rear engine lifting tab is also in the way. It was swearing time. What to do. Well a quick dash inside and a search on www.ls1gto.com showed me I was not alone. It looked like the rear lift tab had to come off and I needed to space the power steering tank forward. Some guys re-welded their tank mount. But there was no way I was going to be able to get that sorted out over the holiday weekend. So spacers it was. Some cut hands and blood later the rear tab was removed. As expected the last bolt was very hard to get at and getting any heft on it required forcing the open end of the spanner to cut into my hand. Nice.

So rear lifting tab removed, spacers on the front one with the tank mount on it and we are half way there.


The next problem was that the coolant cross over was too high and prevented the intake sitting down nicely on the heads. Out with the hammer and a few blows with the rubber handle had it sitting down enough. Of course violence is not without risk and the pipe got some hairline cracks for its trouble. I mixed up some loctite metal weld and gummed it over the cracks. Fingers crossed on that. (Im planning on an LS7 clutch soon so will get a new cross over with the clutch just in case the current one leaks)

Here is a closeup of the spacers on the front to allow the fuel purge to connect. I just got some M10 bolts from the hardware store and some M12 extra wide nuts to act as the spacers.

All that remained was final assembly and to replace the radiator coolant. You don't need to empty all the coolant out, just enough to empty the fill tank and drop the level below the heads so the cross over pipes don't leak.

All done finished. My over the radiator intake required trimming as well again due to the extra length. Also I think the NW90 is slightly larger in diameter so getting the intake on was tough work. I didnt push it right on as there were some cracking noises starting at that point. Perhaps I will need to dremel out the inside diameter a touch so it slips on better. However it has a sharp raised edge which should stop it slipping off, plus the hose clip.


So how does it drive? Well as Im running speed density I will have to relog and adjust VE to compensate so my initial drive showed power much the same. Throttle response as expected with a 90mm throttle was much improved. Im not sure if Im getting clutch slip or loss of rear tyre grip as usually when it brakes traction I get severe axle tramp. More info to follow on the VE gains from the intake.

Oh idle was very close without needing to alter anything over the stock throttle body and intake. Also Ive not yet noticed any issues with leaks which others have had with this intake.

However I think the following things are good to do to minimise the risk of leaks with the Fast.

1. Get as much stuff off the valley cover as you can, tape, clips etc (as well as the mandatory coolant pipes)
2. Use new intake gaskets. The Fast ones looked a little thicker than the stock ones on the LS6 intake. But that might just be age.
3. Make sure if you pull the halves apart you seal them back up well. I used some extra silicon sealant at the joints.
   

More bloody stuff to learn

An interesting past couple of days.

Especially the 2hrs of dyno time which I learnt a lot on. Like my "street" timing sucked. Anywhere from 10-0* out. Varying all over the place. The bottom half is now tuned but soft tyres and overheading dyno's put paid to a full tune. Driving it now I can definately notice an improved bottom end. So am looking forward to doing the whole map.

Im going to fit my Fast90/90 though as it takes so long to tune I might as well put all my mods on and get AFR correct then do timing on the dyno. I was only 65rwhp off a 7L Z06 corvette this time, hopefully with the fast and full tuning that will come down to under 50.

Anyway Id always wondered why you want IAC counts low when intalling cam's opening throttle stops and drilling the blade. Daniel at Chipmaster came up with the goods again. Makes perfect sence. Basically keeping them low, say 40 means if we move them to 4 counts to 44 we have made a 10% change. Whereas at 100 counts a move of 4 is only 4%. That means its easier for the PCM to control the idle when the counts are lower. I guess it depends on cam size and how much it needs to move. I think Id use RAF tuning to get idle sorted and see if its still controllable. If not get the drill out.

My Wideband wasn't reading properly recently. Looked dead, so thats bad. Im going to have to try and sort that out. So tuning will be delayed until I sort out the wideband and get the Fast intake installed. Hopefully this can be done over Christmas.

Post SEMA madness

Well thats SEMA done. Spent loads of time standing and talking to everyone on the efilive stand. Learnt loads from Jessie (wait4me) plus from Ross and Paul about Duramax diesels, finer points of the software etc.

There were far too many shinny things like the new LSx GM Iron block etc.

Anyway back in the UK all is well, its winter and the car is idle in the drive. I have a few plans now.

Basically I got a power run and was only 80bhp off two brand new Z06's so while thats good, its not good enough. The power run was marred by the dyno operator flooring the engine at 800RPM, 100% throttle in 4th. Ive never tuned it there, so 4* of timing was pulled across most of the range. Im sure that dropped me well down the scale.

I have also purchased second hand a set of 1-3/4 4 into 1 headers with 3" collector to replace my current set. The aim is for a full dual 3" exhaust.

I'm going to get my emissions level checked to figure out if Ill need cats, then Im going to get it dyno tuned fully across the entire spark map. If I can unlock more power then perhaps I dont need to take the plunge and BUY A 416 CUBE STROKER!
However the likelihood of coming that much closer to a Z06 is pretty small. I suspect that a new engine is going to be required.

Im also now the proud owner of a Nick Williams 90mm throttle and Fast90 intake which I collected at SEMA. So with exhaust, proper dyno tune and the intake setup. I'm thinking Ill be getting a lot closer to the Z06!

My current quandary is do I get new heads and intake or keep my current ones (Which will be restrictive on the larger engine). Im pretty sure I already know the answer to that.. It just means my Fast90 will now need to be sold off along with the heads and rest of the engine.

Anyone in the UK want a nice stout LS1?

However before going to crazy Im going to dyno tune and fit the 3" exhaust and re-evaluate things. Coincidentally this might just well nicely fall into when Patriot performance get their new CNC L92 heads done. Im also hoping its when the US dollar falls further, hopefully past the $2:£1 mark.

SDPC has the 416cube L92 stroker at $4495, not bad at all!

Tuning has stalled somewhat with all my traveling. However after talking to Jessie I'm going to play with my idle a little more. I think I can make it smoother.

Next planned updates will be to report back on emissions tuning and realtime dyno tuning.

Running..

Mr Road Runner is now installed and working fine. Flashes are immediate and its much less work to make changes. Now if only I wasn't so busy during the week I could get to the dyno.

On another tack, this little magic device arrived a few days ago. Ready for some beta testing action.
Its working pretty well and looks very professional. Not much more to be said at this stage as its on the beta program and under NDR etc. However Im off to look for some LS2 and LS7's to see how the scanning goes.

The car is going pretty well now. Power feels good. Im sure Ill pick some more up on the dyno, but its running pretty well for now. I turned Idle Learning back on as minor changes in the tune would throw idle out sometimes. With the idle learn on its very well behaved. So I think it will stay on.

So once the dyno tune is done I think Ill almost be out of things to tune. No new engines on the immediate horizon for me. Though I might get tempted with the new HSV VE range which may well arrive here in 2007!

Road Runner, the installation

Yesterday my RoadRunner realtime PCM arrived. This little item allows realtime changes to any PCM table that efilive supports. I wasn't able to order the license until the device arrived as I needed the ID and possibly the serial number.

So Ive installed it, but with no license. I now have a disabled car in the driveway! Hopefully the license isn't too far away.

Anyway, on with the install.

For this you will need a 7mm socket and about 20min time. This is on Holdens, other vehicles might take more time.

• First disconnect the battery.
• Then remove the radiator overflow tank. You can do this by pulling it up off its mount and then away from the side towards the engine. its held on in 2 places but just pulls off.
• Then pull the heat shield straight up, it will slide off the PCM surround.
• Next unclip the PCM top cover. There is a tab to the front of the car, if you pull the tab out and then pull up the cover will hinge open from front to back and come away.
• Dig out your 7mm socket and undo the 2 PCM connectors, at this point you might want to consider installing a wire for the Valet mode as well.
• The PCM surround has 2 tabs on the sides which prevent the PCM from lifting straight up. Rather than forcing the sides out to get the PCM out, I cut a small bit off the end so that the PCM comes in and out easier. Decide which option you want to use to get it out. It just lifts straight up once the tabs are dealt with in any case.
• Install is the reverse of removal.

Out with the old. (Note the valet switch which is normally hidden under the radiator fill tank. You can use this to specify max RPM and road speed)



In with the new


Route the USB cable through this hole in the firewall, it drops down neatly at the top left of the passenger foot well.


Once installed I connected my laptop, but could not flash the unit as it reported it as locked. I presume this is because I need to license the device. So now hopefully just a short wait until that arrives and I should be good to go.

Fueling thoughts

Not much to report at present.

Just messing with commanded fuel ratios.
This graph is interesting and shows max economy at 15.4:1 AFR. Right where I normally run for light load.

As I usually run quite lean I have been trying semi closed loop out. It seems much more responsive. I'm not sure if this is due to bank to bank variation or due to the slightly reduced power from the leaner mix. However after over 33,000 log frames tracking bank to bank fueling the average from both banks is identical. Pre heads, cam and SVO 30's I had around 2-3% variance. So perhaps the injectors were a bit out of whack stock.


I will try near to stoich for a while as I like to responsiveness off idle off the richer mix. I will also reassess using the alpha-n fueling for low throttle and map points as it also seems much nicer response wise.

Ive also ordered a Road Runner pcm. This will allow me to make on the fly changes to the pcm even while driving. This is so I can minimise Dyno time. Basically no need to shutdown and flash updates. Should be cool. It will also help to dial in idle issues as you can make adjustments as the engine is running.

By the way, Ive logged 0.87g/cyl recently. Im still hoping to break the 0.90g/cyl level with some more tuning.

Ok after some testing running close to stoich is much better for power.
I logged O2 mv and the following diagram shows the results in Open Loop. Basically the O2 voltage switches as though its fueled in Closed Loop. This is at idle so only a couple of cells. But hopefully I can get the same affect over the rest of the range. Who needs O2 sensors and a MAF!

Exhaust upgrade, the installation

Well today was pipe replacement time. Noise is much the same at idle, though gets fairly loud as rpm increases, no drone though. Im not sure how restrictive the current resonators and muffler is but things have changed for the better anyway.
Basically I had to pull timing at 2000rpm but now I can put it all back in. This may indicate that the smaller exhaust was optimising things around 2000rpm, whereas now its up at 4000rpm. The car definately seems to rev freer and my logging with the wideband has indicated at high map points that up to 5% more fuel is required. I need to fill in the map to get a good idea, but lower map points look much the same, its just the higher ones which need more fuel.
My timing table is out now, so I have started again with a combination table of a stock hsv gts and my previous table. It will take a good few sessions of logging and adjusting to get an idea of where things are now, however I did a WOT pull to 6300 and am still only making 0.82g/cyl or 300g/sec of air. By way of contrast the stock MAF max's out at 511g/sec intake KPa was 99 from a barometric of 101, so intake looks good.

Other than a full replacement exhaust and a Fast90/90 setup, which will both cost megabucks, Im done with the mods. Did a 0-60 to test today, but zero traction in 1st. So will try again another time. Still not thinking about a 402 stroker!

The search for the missing millions.

Well Ive been still thinking about where my percieved power loss is. In theory I should have gone from around 240rwkw to around 300rwkw from heads and cam change. Thats like 100bhp increase. However to me it only felt like maybe half that.

I reread this article here and set off to Simpson Race Exhausts in Berkshire. I had previously noted a smaller section of pipe going from the headers into the cats. They were excellent, do great work at a reasonable price and were very helpful.

Well Im booked in there next week for the bypass pipes. Looking at this pic below from popular hotrodding, noted in the link above. I can calculate my current bhp per cfm at 1.44 (500fwhp) Shocking, as its right off the left hand side of the page! Perhaps somewhere around 70% of Max. Stock it would have been around 1.6 (430fwhp) so thats bad enough, but maybe only 10% down 30% is not acceptable.
So without getting too excited I believe I can say Im definately going to pick a good bit of power up with the exhaust upgrade. It should also definately allow a little more timing, or at least reduce the propensity to knock.

On a more serious topic, Ive been starting to have unclean thoughts about 402 and/or 382 strokers, bad and evil thoughts. I think if I get another 50bhp from the exhaust I should be fine keeping these evil ideas away for a while.

Not much

I can report that H0105 is all thats required to sort out Speedo issues noted in my previous post. I Logged a 80Km drive which clocked up only 50Miles on the Odometer.

Ive gone back to stock injectors offsets due to running to rich on low map zero throttle points. In an attempt to kill the richness off I set DFCO to go hardcore on me. Anything under 2% throttle at all map and rpm points. Works ok, but just when it disconnects hitting idle or low RPM to prevent zero fuel stalling you get a jerk. I dont mind too much, but I might readjust this nearer to stock.

I tested Alpha-n fueling, it worked nicely. Very responsive, but AFR didnt track commanded very accurately, it was close. However the feeling it gave was nice and responsive, so I will likely continue with testing.

Diversions

My Speedo has been dead for a month or so. No speed reading, no odometer and no trip computer. A post on ls1.com.au and thanks to motomk I had a wiring diagram and some disassembly instructions. Cool.
I knew the VSS sensor was working as efilive was logging road speed fine, so the problem was somewhere after the pcm. I also knew the speedo needle did work, because going into diagnostic mode the needle would wind up to 80 no problem. From the wiring diagrams I could see that the road speed signal also went to the cruise control system just prior to hitting the instrument display. Ok, so I tested the cruise control and guess what. It worked. I now knew the issue was between there and the speedo.
It was then that I recalled someone posting up an issue with UK spec HSV's basically an aftermarket device was fitted to convert the signal to miles from kilometers and it had problems.
A quick search on pistonheads.com and good old Steve had posted up some info from his VTSS. He had removed the device and resoldered it.
Now I knew what I must do.
Armed with this information I set about pulling the dash apart. First problem, no stereo removal keys. No problem, just bend the stereo bracket to clear the console!

All disassembled and instruments removed. Now where is that evil device!
Aha, here it is.

Now going into here is a red and black wire. Steve assumed power and ground. Id agree as it comes from a different section of wiring, likely needed to power satans spawn. Out of the device came an orange and green wires. Now thanks to motomk, I knew the wire from the PCM for the speedo was Violet/White, I could see that Violet/Red was cut and rejoined with a short piece of blue wire, no junction just cut. I can only assume the pleb who's job it was to fit these things cut the wrong wire first and had to fix it. So anyway I could see Violet/White was spliced to green which went into the device and orange was spliced into Violet/White up to the instrument connector. Up to this point my intention was to solder up the device to fix any dodgy dry joints and reassemble. However why not just remove it alltogether!? I knew I could use PCM table H0105 to correct the speed signal coming from the PCM, so Id save messing about, increase reliability and gain about a billionth of a second over the 1/4 mile due to the weight reduction, so I thought Id leave it out.

Here is what Satan's spawn looks like up close and personal. The capacitor next to the incoming wires was broken loose and just wobbled around. If you wanted to fix it, then this would be the repair you needed to do.

So I just reconnected the Violet/White wire together and taped the whole lot back up. Job done.

Take it for a test drive. Now reading Km, but not for long. By the way, I dont recommend test driving with just the instruments and not plugging in the power windows, indicators etc when its 28*C outside, it gets kind of hot.
The only thing Im not sure of is how the Odometer will read if I just rely on changing the PCM output signal. Im hoping that given its only one wire that was being messed with and it seemed to handle the odometer as well as trip computer and speed needle, then I will be fine. Worse case Ill have to pull out the dash again and wire Satan's spawn back in place. Ill update in a few days to report what the deal is.

On a more PCM based note. Im now running EFILive custom OS5. It works fine and takes OS3 calibrations. Basically it extends OS3 by adding switchable timing and fueling for NOS applications. You could also use it to pull timing based on a switch for fuel octane variances.

It also supports Alpha-n fueling which is purely determined by Throttle and RPM, no other inputs such as MAF or MAP etc are used. Its really designed for hellish cams that wont hold or give a vacuum or stable airflow reading. (I wish that was me!)

So Ill be likely making some comments on that in the future given thats now my PCM OS d'jour. So its goodbye to OS3 and hello to OS5.

More idle thoughts

It seems that the question of a smooth idle comes up more than almost any other question when tuning. Especially with aftermarket camshafts etc.
I guess when cruising in closed loop with the MAF just about anything will work. This is due to how closed loop feedback from the O2 sensors and the Mass AirFlow meter work. It really takes the guesswork out of tuning. No doubt exactly why GM use it.
Well throw a cam in there and when starting cold the car will be in open loop and at low rpm speed density airflow calculations come into play.
That sorts out those with good tunes from those that just do the easy stuff.

Anyway following on from those thoughts, Ive done a load of changes recently which threw my tune out. Just spent the morning dialing it back in. Now its nice again. (For the next day anyway)

Take a look at this first image, it shows the idle hunting up and down, spark, vacuum, rpm and if it was shown, IAC counts basically wavering to and fro. If it gets bad enough it will stall. Sometimes the oscilations will increase and get worse. Often when AC is turned on or the Radiator fans startup.


So all in all, it idles, but its horrible. Ok so how do we normally fix this? First we go back to basics and make sure that the engine is getting enough air at idle, or at least getting what it wants. To do this we log both short and long term idle corrections to airflow. These corrections are made by the PCM to try and get a stable idle. In efilive they are known as calculated pid's as they are summed and made into a single value for easy logging. So we make a map with ECT vs the RAFIG pid (Only this is needed for M6 cars, Auto's use RAFPN as well) as the car heats up it will log a map of adjustments required to the Desired Airflow table. Once warmed up, we shutdown and update this table. If you cant get your car to idle initally, you might need to start logging to figure out which way its going and just guess to get it to run long enough to map the adjustments.

So once the airflow is updated. Its worth going into the bidirectional controls utility to see if adjusting the spark and fuel mix would help the idle. In my case fuel was ok (set to 15:1 at idle) but spark was now quite a bit out. Dropping it from around 38 degrees to 28 degree's sorted out a lot of the hunting. Im assuming the new injectors and injector offset tables I have been messing with caused some of this. So easy done, all fixed. Now back to a smooth idle. I just made sure my high octane table and base spark tables were close in the idle and off idle areas, so that transitions were smooth between both tables and all is well. The resulant logs are shown below. Notice RPM is now almost dead flat and there is some slight adjustment to spark by the PCM to hold it there.

So there we go. A short run down on tuning idle for anyone who is having issues in this area.

Radiant

Well today was a mixed bag of events, a badly secured clip that held the IAT sensor in the intake came off and meant that the sensor dropped on the drive belt stripping a few cords off it and causing it to drop off. All this about 70 miles outside of London. I didnt have any tools so ended up with the recovery guy putting what was left of the belt back on.
I couldnt find the metal clip which had secured the IAT inside the air intake so thought Id just check where it went.. Yep, it was lodged at the back of the manifold near cylinders 7 & 8. The guy hooked it out with a magnet and all was well.

Suffice to say metal clips arnt going back in there. The rubber gromit the intake had come with was a bad fit so I need to sort something reliable out.

So that cancelled my trip as I didnt want to get stranded in Wales and have to leave my car there if I couldnt get a replacement belt, so back home I went. I managed to get a new belt and fitted that right away.

At this point things got better as I decided that I would then fit my new injectors and thermostat.

I didnt have a fuel rail removal tool, which is pretty essential to get them off so just followed some info on www.ls1howto.com, pulling the fuel pump relay cranking the engine to dump the line pressure then removing it. Suffice to say even though there was no pressure there is still a lot of fuel in there and you will get it everywhere, so make sure you have a rag.

Pulling the old injectors out of the manifold is easy, but they are well stuck in the fuel rail. All of them took a bit of effort to pull out and left their rubber seals in the rail. Once removed the new ones went in nicely with a little bit of petrolium jelly. Here is a pick from halfway though.

Note the IAT and MAF sensor connectors are now tied away with tape too after the earlier mornings troubles!

Next was the 160*F thermostat. All in, both jobs only took a couple of hours. I set the fans to come on around 80*C and the high speed fans around 87*C. To celebrate I also pushed timing up 3% across the board.

So a flash of the changes, including rescaling the injectors with RedHardSupra's injector table and I was away. Immediately I noticed VE was up to 10% out. Cool I thought, it did need more timing. I added around 5%, but then remembered some comments on Injector Offset. Basically the larger injectors are lazier at low duty so need more time to open etc. Joe who posts on efilive had posted some new tables which had worked well for him so I have used that as a starting point and will do some more logging and check to make sure that all that extra fuel is required. Hopefully it is and the consequence is more power. Knock is not appreciably increased over what it was before, that is, a tick now and again but no sustained knock under load. Only really there on throttle tip in.

So only exahust upgrade to go, some final tuning and off to the dyno. Also time for a few gtech runs I think.

Refinement

Got my 160* 'stat today and SVO's
Also playing about with Base Spark and High Octane tables. I think Im getting a little jerkyness due to low throttle positions swapping between both tables. Especially when hardly touching throttle. I have made both tables a little closer in value to see how that goes. Its possible its DFCO messing with things too, though often the RPM value appears below the DFCO enable point.

So a long trip tomorrow, then sunday, thermostat installation day. I think Ill take the spark plugs out too and clear off the corners as recommended by Vizard. Im hoping to be able to push spark up by around 10% across the board. We will see. I have 21 at WOT and 19.5 at Peak Torque which is very similar to my stock tune, so I guess thats not too bad. KR is almost non existent. As I think I mentioned earlier these heads will need less timing anyway. So maybe 22-24 deg is optimal.

I need to sort out the exhaust gaskets as Im getting some cat bypass pipes done up and they need the gasket to make the flanges up. I think Ill go 2.5->3.5->2.5 so that the 3.5 section acts as a resonator and terminates the collector length. Otherwise it will be 2.5 from the headers way back to the current resonators, which from my reading appears too far. Though Ill have to measure up to be sure.

So the current series of mods is coming to an end. Soon it will be time to go and see whats up on the Dyno.

Exhausting

After removing most restrictions with the new heads, cam, intake system etc I have now turned my sights on the exhaust system.

I spend some time with a tape measure and clamp measuring the diameter of the various parts of the exhaust system.

Well its not too good. The cat back looks ok, 2.5". The headers are ok, ending up in try-y configuration with a 2.5" exit. The problem then is the 2" pipe into the cats with the O2 sensor in there too! Thats less than 3.14" sq area compared to the rest at 4.9" sq for the 2.5" section. It will even be less due to the O2 sensor in there. Now if I knew what I was doing with calculating exahust flow Id be able to verify that the exahust is a restriction. Though I have read another Vizard article which states dual 2.5" exahust will support up to 500bhp without restriction. So based on my hope to be at around that level at the flywheel the exhaust is going to be a restriction with its 2" bit, so out it goes.

My options are to replace the cat system with a bypass pipe for "off road use". This will allow me to replace it for "road use" and emissions testing. Hopefully I dont forget to replace it and just leave the offroad pipes on :)

As per usual good old Mr Vizard has an excellent article on exhaust selection and design here.

From what I understand the main summary is that exhaust tuning can produce up to 500% increase in cylinder scavanging over what the usual induction stroke of the 4 stroke cycle produces. Primary header length is not as important as collector length, and wise placement of open chamber or resonator boxes helps to terminate the effective collector length. A good rule of thumb is 2.2cfm of exhaust flow per engine bhp. So a 500bhp engine requires 1000cfm of exhaust. In addition a 1"sq pipe flows around 115cfm. So from this I can see my 2"sq pipe will only flow around 350cfm, or a total of 700cfm (2 pipes) a 50% increase in exahust flow is required to remove the current restriction! And worse because both 2" pipes have an O2 sensor blocking half of it off!

So anyway looking at options now, which include replacement headers as well. I think this is going to have to be the end of the purchasing mission. Finances have taken a hammering recently so hopefully there will be no mechanical restrictions, or at least only minor ones. (Like not having a Fast90/90 setup!) Still waiting for the thermostat and injectors. Im pretty sure the 30lb SVO's will be ok as Im not at 100% duty with the 28's yet. Unless the replacement exhaust makes this change a lot then I should be fine. RedHotSupra has recommended 42lb injectors as they will fit more nicely at the 80% level. In retrospect this is likely to be correct. However the 30lb ones should be ok, but will sit at a higher level.

Still aiming at 400rwhp

Yay my first planned mod has finally arrived

Super cool awsome. My otrcai has arrived. Can you notice it in this photo?

It was made white for me by efi dynamics in Melbourne Oz. Thanks to Les also from ls1-australia for organising it for me. I chose white so it reflected the heat as much as possible. I might even put some silver reflective tape on the bottom. Might help it resist heat soak a little. Should be worth an extra 50bhp, what do you think!? Ok well maybe 0.1bhp anyway.

I had to take a sliver off the neck so it fitted back far enough for the bonnet to close. Nice and snug, so its not going anywhere. Did a test drive up the road. Definately makes more power. Some good sideways action at the round about to check and back home. I have a reasonable drive coming up thursday and an even longer one at the weekend so Ill get some good logging done.

Well new injectors 30lb Ford SVO's (yes I said Ford) are shipped. They should give me plenty of head room and are accepted as a good choice for heads and cam vehicles that need a little more injector capacity. Stock 26lb ones are only good for stock engines. The later 28.8lb ones are ok with mild cam only. But I logged a 92% duty the other day and that was still under 6000rpm so definately need more. The Ford ones rate around 36lb on the GM pumps due to higher pressure, this should be good for around 650bhp based on my understanding of BSFC, which admitedly is probably pretty shocking.

BSFC as I understand is the engines ability to turn fuel into power. A more efficient engine will get more power from each lb of fuel. Forced induction engines are good, as are some high compression NA engines. Take a look here for Mr Wikipedia's take on the matter.

Ok so now I shouldnt be intake restricted any more. Thermostat will help keep engine and combustion temps under control so I can get a little more timing.

I did a traction limited 0-100 of 5.6sec the other night. Not so brilliant. But that was my first go. I will run a few more times and practice my launch etc. I think I might be able to get it to very low 5's and will some luck and probably more tuning even under 5!

Also today I messed with a number of tuning tables in order to arrest my reverse full lock low speed stall. It appears totally fixed now. Cool. I might celebrate by dropping idle down a little to 780 from 800 and see how it goes. It will idle at 700 rpm, but is a little tetchy about doing so. I think 780 might be good enough.

I thought so

A day spent on and under the car again today.
Some new NGK-BKR6E-11 plugs, well cheap I think about £12 all up shipped to my door. They are shorter than the stock Autolite plugs so will create less compression and run cooler. I pushed timing 0.5 degree up to celebrate and no KR was logged so things are heading the right way. Cold air intake and Thermostat to come.

I also ported my throttle body today. Here is the pic, a little blurry, but there you go.
An excellent writeup here on how to do this. I cancelled the BBK one I ordered, everyone says there is no point upgrading unless you go for a Fast90/90 setup.


Also here is a pic of the old plugs I pulled out. Ive done some spark plug research and Im guessing they looked a little lean/hot. But within acceptable limits. Take a look here for an excellent link on spark plug reading. New plugs are gasketed, which is the recommended plug for the darts. So plugs are now as they should be. The old ones have been consigned to the spares basket.

I also found a small exhaust leak, which was the likely reason my girlfriend was complaining the car was making her sick, "worse than before". And there I was thinking it was my driving all along, or the increased power and whiplash etc.

So good progress, slight increase in power and hopefully more to come with the remaining parts.

If you havnt done so already PORT YOUR THROTTLE BODY! Its easy and rewarding.

Last fuel fill the distance remaining read 420 Miles, which is pretty good, same as prior to heads and cam upgrade. So there you go a nice small port high flowing head with good compression and a mid-ish size cam can get you good street manners, more speed/power and retained economy.

Just a little by the way. The Dart heads have about 0.100 less valve clearance over stock heads. So notching pistons is more likely with the Darts. The valve springs are good to 0.620 but the drop wont support that with out compatible pistons.

Another learning experience

Ok, so in hindsight (which is often the way these things get found out) Id have been better with a slightly lower compression setup. Im still confident that I can make do with my current setup with the mods mentioned above, but Im right on the edge. Timing is such that knock is not an issue. Its just not ideal for power.

So today I ordered the 160deg thermostat from Summit. In addition some serious WOT action today showed that my new slightly higher rated injectors wernt going to cut it as they were running 97% duty. With the new intake and hopefully additional timing which should require a little more fuel to get back to commanded fuel ratios Ill require some extra headroom. Actually the recommended headroom is to aim for 80% duty cycle anyway. Stock early LS1's are almost at 100% off the showroom floor! Anyway the reason I mention this is that I got some Ford SVO 30lb injectors. They will work out at around 36lb with the GM 4bar fuel pump and give lots of headroom.

I thought seeing as I was at it I might as well order a BBK 80mm throttlebody as well. The budget is now seriously blown and expenditure needs to be trimmed right back as things are getting out of control. Hopefully I can restrain myself and not buy a new exhaust system. The current one is ok, twin 2.5" but has cats and 2 mufflers on it. I need to pass emissions and see what my margin for error is. Hopefully it may allow the removal of the cats and while Im at it one of the mufflers. That might help airflow through the engine as well. Im currently running 0.85g/cyl which is about 0.07g/cyl off what Id expect (0.92g/cyl) Im hoping timing, throttlebody and cai will get me closer.

Timing and Octane

Well the past few days have been interesting.
I managed to fill up with 100 octane in Germany where its cheaper than 95 octane in the UK.
This allowed timing to be increased 3 deg with what seemed like a small increase in power.

I had been wondering why, if lower timing was better, why not just run lower octane and lower timing. Well after some reading and investigations the answer appears that if you run too low with timing the combustion will still be happening when the piston has past its best position for combustion pressure. (Around 15deg ATDC) So the ideal octane and timing is the one which puts the most pressure around 15 adtc and is all spent before the exhaust valve opens.

From others comments and feedback this optimal timing appears to be around 24-28 deg, now there will be variables such as combustion chamber design of aftermarket heads etc which could move this a little one way or the other.

My timing with 95 octane was around 18 deg. With 98 Im back to around 20 deg. Im hoping with the changes detailed here to be able to creep towards 24 deg with no observed knock.

So Im now officially running 98 octane and am embarking down a track to optimise compression and timing settings. My compression with Dart heads is right on the line, so extra margin for error will be good and hopefully allow more power from optimised timing.

A quick read of this excellent FAQ will reveal more for those interested. Particularly section 7.

So in order to see how this goes I have just ordered a set of 8 x NGK BKR6E-11 plugs which are a gasketed equivalent to the TR6 plugs. They are standard copper. But if they work well Ill change to Iridium.

Anyway my quest for reliable compression and timing will be as follows;

• Fit OTRCAI cold air intake to reduce IAT temps (on its way, hopefully here in the next week or two)
• Fit lower temperature Thermostat 170*? (currently researching this, David Vizard has a nice article covering all this here)
• Fit colder spark plugs as mentioned above

Other changes such as combustion surface polishing etc are out of scope for the time being, as the engine is already assembled. I could also retard the cam and flycut the pistons (dual benefit of allowing more lift and dropping compression) but wont for the time being.

The maximum benefit looks like it will be realised by the use of a lower temperature thermostat. Here the idea is to reduce heat soak to the intake air and closely related to this, the combustion chamber pre ignition temperatures. Thus inhibiting the spontaneous combustion that goes with knock. See the chart below from the David Vizard Popular Hotrod link above. My DCR is 8.3 or close to, according to this calcuator here. (Use 3.91 for gasket diameter, 3.9 for bore, 3.62 for stroke, 6.1 for rod length, 0.055 for stock mls gasket on stock ls1)

So based on 98 octane (98 + 87)/2 = 92.5 I need to be looking at a 170* thermostat and regulate engine temps around there. Users of the popular 160* thermostats report general operating temps in the mid 170's so. I think a 160 might be the go. I can regulate things somewhat with fan operation. Just need to order the thermostat now...

Other than that, I spent a good few days logging and one lap of the Nurbergring. Which is situated in the nice little town of Nurgerg in SW Deutchland. I logged the lap, but sadly cronic understeer from shoddy worn cheap chinese tyres prevented to much speed. I will rearm with better tyres and schedule another visit. It was great fun. Next time Im going to book a lap in the BMW M5 Taxi that takes people around. Apparently the drivers are excellent and will do a very very fast lap including some good sideways action.

I also attended the F-Body meet in Meerbusch, a good crowd from throughout Northern Europe were in attendance. Mainly older 3rd gen's but a few LSx vehicles were around. I took the organiser for a blast with a few of his friends. He said power was very smooth and fast. Which reminds me, its soon time to redo my 0-60 times.

Clarity and chaos

Well, day 2 saw the horrific discovery that the reason why the WB02 wasnt working was that it wasnt plugged in!

Starting had been a problem so I swiped a cranking VE table from a modified tune on www.holdencrazy.com. Starting is now fairly good, a couple of turns and its away rather than protracted cranking and throttle use being required to get it started.

Once started things got real messy, the idle was hunting up and down pretty badly. I recalled some comments regarding idle spark control and an investigation of tables B5934 -> B5936 showed that up to 25 deg was being pulled on startup. This showed me where the 9 deg total timing was coming from. Once warm it settled down and spark was running what I had set it to in the base spark table. So some big chops to these tables were made, basically 50% off each overspeed table. Underspeed was left as is. This seemed to make a good difference as well as generally reducing the cracker values overall. I had dialed my desired airflow in fairly well on day 1 so just a small amount of extra air was required.

I should mention that my baseline tune was a 2004 HSV GTS converted to efilive custom OS3.

Low level VE cells needed to be reduced a little, nothing more than 5-10%. Some higher end cells have gone up by around 7%. Im going to compare with a tuned VE table shortly to see where the gains, if any are.

I still have some low speed coming to a stop issues and when fan and power steer load goes on it can stall. I will add some more air for the fans and look at cracker and follower for idle transition stalling at low speed. All in all its come a fair way so far.

Spark is fairly close to stock a little less in parts. Compression is a full point up and spark at idle needs to be around 8 deg more than stock cam. A few more weeks of tweaking and it will be off to the dyno.

I wish I could have got a larger cam, but this one has a very wide powerband, I seem not to have lost any low down power except the car will surge in 1st gear crawling along the road with no throttle, so I guess no surprise there. Basically exactly my requirements. I have to meet emissions standards so it was 224 or less sized cam. I chose 220 for a safety margin. The car pulls well into the 6000rpm range. Im guessing Ive added power over around 3500 rpm to redline. Not sure how much yet. Its not like night and day which is what I was expecting.

Mr Dyno will tell all.

Stage one... again

Cam bearings were just within spec. So cam is now in.
Strangely piston to valve clearance was not sufficient to use the higher ratio rockers. It cleared, but not by enough to allow for heat and wear. Others have been able to get larger 23x duration cams in without fly cutting the pistons however I did note that my 0.006 spec's are very close to the larger cam specs at that lift. Perhaps due to high and fast lift. I just checked against the F13 cam and the crane has a later IVC and more 0.006 duration. So I guess that answers that. It must have slow ramps.

Anyway, car would not idle initially, I gave it 20% more RAF (Desired Airflow), still not good, so 20% more and once slightly warm it idled ok. I did a half baked log to check for idle air, but had to keep the throttle open to get it to run without stalling. Once warm it was fine, so Ill have to relog when cold. Its likely even more air is required.

Inital idle spark was 9 deg for some reason. It should have been over 20, so I will need to log some more and see where it got the 9 from. I overrode the spark with the bidirectional controls and got an idle map of 38kpa with around 34 deg spark. The engine runs crap with 9 deg spark, no wonder it was stalling.

I think the shop must have pushed the WB02 recall button, you know, the one with the red LED that nobody should touch, while wondering what it does. So anyway no chance to do any VE tuning as you cant recal the WB02 until the car has sat for 8 hours or you unscrew the unit from the exhaust and recal in open air. Suffice to say Im waiting 8 hours as its windy and rainy at the moment.

I drove off with my idle kind of ok except for coming to a stop when if I turn in on the power steering the car cuts out. Might need some cracker action or possibly even more air as mentioned above.

Next issue is due to no view of AFR I logged NB02 voltage as a kind of rough view on things. It turned out I was running over 1V constanly at low MAP (ie) very rich. Miles to go was falling like seconds on a clock. I pulled over and made some adjustments until the voltage was visably moving around. I drove like this for a few miles to check that the O2's were still working ok then turned on semi open loop fueling in custom os3. Basically if you command 14.63:1 the O2 sensors will trim the fuel to stoich. If you command any other values O2 feedback is not used.

This worked much better allowing the car to run pretty well. The STFT values showed that the VE table was out as at idle they were -15% and at some points +10%. This will be sorted out when the wideband is working again.

I swapped in my old spark map as the GTS table was showing up too much KR. Maybe due to the increased compression ratio or 95 Octane fuel. Lots more experiementing needed with spark and fuel.

In fact VE is fairly easy to dial in when you have a working wideband. Idle will take me a bit longer and spark will take the longest. Ill have fine tune it in on the dyno.

Af far as how the beast goes now. Im not sure. It feels at least as good as it was before and slightly beefier in parts. Nothing major. But Ive kept out of enrichment so far and its in a pretty basic state of tune. Idle is quite sedate, nothing too hairy. If it wasnt for emissions compliance I think Id go for the popular 224/228 comp cams grind.

More info once fueling and spark is dialed in further.

Under the knife

Well the doc has my R8 under the knife. We discovered the cam bearings are showing signs of wear which seems to be quite common. So the bearings are being measured out to check for signs of uneven wear etc. Ive got my fingers crossed that they will be fine otherwise its an engine removal and extra ££ to sort them out.

Worse still Im booked on a ferry to Europe late may!

Hopefully all is well, we will see in a few days.

T minus 20

Finally all my parts are here. It took UPS 3 failed attempts to actually deliver on their delivery date. I was told 3x that the guy would be around, each time they never turned up. Suffice to say that the 3rd time, severe anger management was required. Luckily the local manager sorted it out and someone dropped them off. Still if I could be bothered Id chase them up for compo. I had to take 3 days off to sit at home. Perhaps I will write in and complain anyway.

Still that aside. The Dart 205cc heads are in. There is a little casting flash and the chambers arnt polished. But I dont think Ill get around to doing much with them. Id have to pull the valves off. Make sure they went back on the right ports and be careful of not damaging the seats. So for the extra bhp from removing the very minor flash, I think Ill leave them as is.

Car is booked for later in the month to get all the goodies installed. I have a trip to France to do before then. Pity I couldnt have it done before then.

So anyway back to tuning. Ive been helping a fellow LS1 owner sort out their tune. The o2 sensors were placed back pre cat as the previous tuner had put them post cat. Well what do you know, the car now passed fast idle test, which it used to fail with excess CO emissions. The guy was having fuel consumption issues so we dropped idle speed and advanced up the timing a little. It idled nicely at 650rpm. However perhaps because of this it failed the natural idle test. Again excess CO. I read somewhere that a nice hot engine and faster idle and strangely enough more retarded ignition should sort that out.

Im now wondering if thats why the OEM tunes run such low timing and high idle speeds. Not for fuel consumption, but for economy. Anyway Ive offered to return idle to stock so he can get the emissions checked out again. I think we might have it sorted if thats the case.

Otherwise Ive been playing with fuel octane and without changing any spark timing running a higher octane, 98 RON seems a little more peppy. I need to do another tank of regular 95 RON before I know for sure which is better. Mind you come the 11:1 Dart heads and I think I will have to use 98 RON anyway.

Id been having some issues with efilive OS3 where commanded fuel did not match acutal AFR. Basically the efilive guys had seen the issue before and the PCM was entering PE mode and not exiting from it. So AFR was at PE even when off the throttle. Anyway I decided to change more PE triggers and not just the MAP trigger. I set TPS to 100% for all RPM points as well as setting commanded PE AFR at 14.7:1. Since Im running a fully flexible AFR map as in my last post I should never need PE mode. So in theory I never went into PE, except that I was! Anyway it now seems like that little monster is sorted. Ill have to recheck a few more times to be sure as it was intermittent in any case.

When I said all my parts were in, I actually meant all my parts except my otrcai, which should really have been in months ago. I had comitted to one last year. Apparently its been ordered and is on its way. Still my brother lives in Oz, so getting him to mail me one shouldnt be a major issue if the one I have lined up falls through.

Hopefully my next post will be with all the parts installed and no issues to relay, except excess power and lack of traction.

For those looking at getting good power on a budget here is the basic run down.

Parts: (Prices in $US)

• LS6 intake and injectors, bought from ebay in OZ from MantaLS1 (Thanks dude) $175
• Crane Cam HR14400067 grind, same as Vinici cam and known as SDPC custom $310
• GM MLS OEM Head Gaskets
• GM OEM Head Bolts
• Dart 205cc LS1 Pro1 heads $1295
• GMPP LS1 Oil pump $69
• Rollmaster timing set $99
• Various gaskets for timing cover, pulley bolt etc $100

So total cost is about $2000US plus shocking shipping costs of around $1000US, but that includes horrendous UK VAT at 17.5%

Stock the engine was rated at 345bhp, Im hoping to see near on 500bhp on completion. I might need a new clutch and injectors, but Ill worry about that later.

The waiting game

Well, Ive been watching the grass grow for a while now. Those Dart heads dont seem to be getting any closer. Apparently they are backordered for weeks, selling like veritable hotcakes.

In the meantime, Ive taken the knife to my tune with economy in mind. Im still running open loop with no O2 feedback and Speed Density mode (MAF disabled/disconnected). Soon a new MAFless intake will be here too.

In the meantime I have done some changes to efi OS3 table B3647 as below with the idea being that stock lean cruise and fuel cut off do much the same thing. I have basically leaned out low load points. This is a table of commanded AFR vs RPM vs MAPThe car runs fine with no decernable loss of power.

In addition a few of the afterstart enrichment tables and values have been pared down.
I have taken around 25% off these to lean out startup. Commanded fuel when cranking, initial fuel prime etc. The car still fires up fine so Im going to hold off getting too radical on cutting this down until the new cam and heads are in. Again things still work fine, however hopefully Im now using less fuel.

I might be spending some time this weekend with a fellow Holden owner taking a look at his tune. Its running zero trims but runs rich on the exhaust analyser. As mentioned on a previous post, his O2's are located post cat. So I suspect changing switchpoints will also require changing the VE to take about 10% fuel out. Should be interesting in any case. Hopefully we can sort out the issue.

My brakes were well seized up. So after a visit to a workshop they are now running well. Ive not hammered on them yet. Too much stuff all over the place in London. Looking forward to the cam install. It cant happen soon enough!

Oh one more thing. I read an article which stated MBT was around 3-5 degrees from knock point. I'm not sure what engine that was in, but it was good to get a fairly definate indication for the best timing.

Daniel at Chipmaster in Oz has a nice little page on tuning up here too.

Return to darkness

Well after an eventfull holiday with no less than 3 tickets in NZ. This included a shocking display of NZ Police incompetence with me being told I was banned for driving in NZ because my NZ license had expired years ago and that my UK license and Passport were not acceptable, despite the so called officer telling me that visitors had the right to drive for up to a year on their UK licence. Needless to say I ignored his pointless and childish grandstanding.

Oh, the other tickets were for speeding. One for 114Km on SH8 with a 100Kmph limit. Also fairly pointless on what must be one of the worlds least busy roads. The other was 127Kmph. Lesson learnt was to not watch the road and other traffic and instead watch the speedo and ignore all external events and road conditions.

Aside from that the 28 deg C weather has been replaced by sunny London's sub zero overnight temps, dark rainy days and 5 deg C daytime temps. Nice.

I had time yesterday to roll under the car and get dirty replacing the shifter with a Rip Shifter. The front bolts are a nightmare, but once the trans is lowered a little its actually quite simple. Shifts are shorter and more direct, much nicer, though I think I preferred my B&M Shifter in my camaro for shorter shifts... and cost. Total time for install was 4hrs. But you could take 1hr off I think as I messed about from the top with the tricky bolts rather than just dropping the trans as per the instuctions right off the bat. Another lesson learnt :)

I have some NZ pics showing the Commodore and some nice scenery. For those who like V8's, open roads and scenery, I recommend NZ. The west coast is nice and windy and lots of fun can be had without exceeding the speed limit (to a certain extent).

A fellow UK owner dropped by yesterday to get me to do some scanning. His tune was running rich and dispite all new parts failed emissions testing on a stock engine! Obviously something was wrong. We took a look at the tune and while LTFT was pretty much at zero there were a few weird things.

O2 switch points were all set over 500mv, in addition the sensors are apparently located POST CAT, which would cause them to read leaner anyway and dump more fuel in. His VE table was around 10% more than any other stock engine tune Ive seen at low RPM. I think he needs to change his switchpoints and get the sensors back into the right place before the cats, preferably in the collectors. I need to ask him if his headers have sensor bungs. Most do.

Alternately we can run open loop, but this really needs a wideband to check how things are going given his O2's will give us even less useful info than they normally do. So a few interesting points to look at. I think he will make some more changes to crack the issue.

Encore un fois

Ok, so Im sitting in NZ at the moment after tuning my friends SS Commodore. Good results, though he has stock exhaust manifolds and MAF. The tune was mafless and based on the R8 tune. I had to pull some timing from 4500-5500 RPM to prevent real knock. Though the rest of the table is pretty much stock R8 285KW.

Quite pleased with the results, I think he will get an OTRCAI to minimise intake temps as they have a considerable effect over 30deg C with quite a bit of timing being pulled.

I used a combo of efilive OS3 with open and closed loop. Low map was open loop leaned to 15.4:1 AFR, while midrange was closed loop and WOT open loop as normal. MAF codes disabled and MAF disconnected.

Took 13 revisions to get it to where Im happy with it. Some of these were on/off settings to try one then the other and back again. Compared to my over 130 tunes, 13 for his isnt bad. I kept a little conservative, though he asked me to sharpen it at the end so he had max power. There is still no knock showing, though Ive seen him drive and its not pretty, WOT from idle in all gears!

Anyway, thats my second tune so far. Ive decided that for mechanical and volumetric efficiency reasons I must purchase a set of Dart LS1 Pro 1 heads of 205cc capacity. That should give me 10.75:1 compression with good flow rates. Ill order these as soon as I get back to the UK.

Im still waiting on an OTRCAI, there are none in NZ, or at least none I can find. Im looking at the Orssom range from Charlie in Oz. A new batch are due any day.

Timing revisited

Ok after much hair pulling trying to remove all trace of knock from all logs, I had found I was going around in circles. No matter what timing was there would always be some logged knock.

After some discussions with fellow tuners the consensus appears to be that as mentioned previously, real knock you should worry about is "saw tooth" in shape, while incidental and false knock is just a small spike which will show now and again. Or in other words "false positives". Just like an anti-spam engine will block good emails on occasion, the knock sensors will log random nothings from time to time. However big spikes and saw tooth shapes suggest real knock so be wary and careful not to take this post as a recommendation to allow real knock to exist at all.

So in summary Im pretty much back at my timing table I ran for the dyno pull happy with the fact that the odd tick on the log now and again is acceptable. With this in mind Im warming up to an OTRCAI purchase to go with the cam and possibly some Dart 205 or 225 heads.

Sparky

As time progresses my right foot seems to fall heavier on the throttle putting me into load areas previously not dwelt on for too long before. Ive pulled some more timing out and am now sitting on around 20deg total at WOT, part throttle timing has also fallen. Interestingly enough power is much the same. This reinforces the often read and heard line that "best timing is miles away from knock". The idea being that you should run the minimum timing you can to attain peak torque. This point is known as MBT (Minimum best timing) afterall burning the charge before TDC means you are fighting the compression stroke. To set timing at minimum buys you some safetly for dodgy fuel and conditions.

As mentioned previously this is ideally setup on a load dyno. I tried to get some 0-60 times on myGTech the other night as a kind of "check" for my tuning changes, alas, it appears that it may have completed its life on earth as it was spewing out non intelligable figures not related to the mode I was in. Ill try it again and have another go, else its time for an upgrade to the GTech-R version which does torque graphs. Perhaps you are wondering if I may have hastened its demise? Ill leave that question unanswered.

Very shortly I shall have in my posession the following items;

• LS6 Intake
• 28lb injectors
• OTRCAI
• Short throw shifter

These plus my 220/224 cam = more tuning fun.
I have tentatively booked in late Feb for the cam and other parts install. Though Ill put the shifter in myself beforehand.

Idle thoughts..

Firstly a clarification of an earlier post on KR. Tordne brought to my attention the fact that I mentioned voltages fluctuations can indicate false knock etc. More correctly this is fluctuations in the recorded KR, which does relate to voltages obviously, but the item to log and observe is the KR in degrees, not a voltage reading. I dont want to edit previous posts except for grammar as I think it shows the learning process more clearly where there is slightly confusing statements, but thought this was worth mentioning anyway.

Ok so after more reading and yesterdays trials I think I now have a good understanding of Throttle Follower and Cracker settings and they actually have nothing to do with idle! They are for transitioning to and from idle.

A lot of the idle tables are inter-related and some effects that appear similar can be down to other tables, here are my current thoughts on 2 off the idle transition tables.

If you have an issue when coasting and going into neutral where rpm rises I think this will be a Cracker issue, you need to reduce the cells where the problem occurs.

The Follower is for leading into and out of throttle transitions so rpm's ramp in and out rather than hammering in and out. (Perhaps to prevent wear on the driveline!?)

The desired airflow (RAF in HPTuners) and IAC Parked Airflow tables are the ones to give you a smooth parked idle from cold to warm.

So if your vehicle bogs off the line, you should look at the Follower values, if it rasies or drops rpms coming to a stop its likely the Cracker tables (during shifts also consider the Follower as it decays airflow on throttle reductions).

If you put too much Follower in you might need to reduce the Cracker accordingly.

Also as per my previous post if you want more off idle throttle response take a look at the Follower tables (The the added airflow and multiplier ones)