While planning the next set of changes I decided to try and chase down some minor idle issues. Like RPM dipping at low speed when in neutral.
After some reading on EFILIVE forums for idle transition and idle tuning I made a few maps and pids and went logging from startup to full operating temp.
I pasted the changes into the Desired Air Flow tables and things are now much smoother. I think the 1.8 rockers might have thrown the stock idle table out a little. Good stuff, Im now prepared for some cam idle tuning next year come cam install time.
That was too easy, so I decided to look further into suggestions that you can get a similar effect to a "pump shot" by messing with the throttle follower tables. This handles the transition from idle to running airflow. Factory default is to trickle changes in until throttle position sensor (TPS) is at 13% at which time it is increased 6 fold! There will be some interpolation, but I decided to make it more linear, so scaled the roll in from 3% TPS and set the mulitplier at 1200 to match 1600 RPM lead in. The car now launches off much more confidently without the delay from idle requiring 15%+ TPS to make it do anything. Another sucessful series of tuning actions and no observable ill effects.
I will be logging a lot come tuesday as Im off up North again so will check to see if this additional airflow has affected my AFR readings and hence VE table. I doubt it, as its only put in on TPS +ve delta changes, then decayed out.
Saturday, December 31, 2005
Wednesday, December 14, 2005
Stage one complete
I decided that my tune was close enough to warrant a trip to the dyno to check WOT fueling, timing and power.
The guy was very helpful and didnt mind me digging my laptop out and hooking myself up. On his advise Im now at 12.5:1 at max torque, which gained me 3bhp and 2ft/lb over my tune.
I basically overloaded their dyno as you can see my power run is cut short. I will try somewhere with a beefier dyno next time. I think I can make up more power with my LS6 intake and a new otrcai (Over the Radiator Cold Air Intake), plus run some high 98 octane fuel. Im also running cats still. Anyway peak power is normally aroung 5500rpm my run was cut short under 5200rpm so I wont know till the next time where we are at. Indicated flywheel power is 362bhp with 364ft/lb this is because the dyno measures trans loss on the overrun, apparently pretty accurate.
So I think for now Ive got things about as good as Im going to get them unless I retune for 98 octane. I think Ill just leave things be until March when the cam, intake and injectors all get changed then retune for 98 octane too. Im hoping for at least another 50-75bhp. Apparently the LS6 intake is worth 20bhp itself, plus maybe 10 for the fuel and 40-50 for the cam. We will see.
Injector duty was at 92% on the dyno so the new injectors will be required.
Tordne seemed impressed enough to request my tune and go looking for an HSV285KW base tune too. I had based my timing on the HSV table and found it very good. This was the last HSV LS1 engine before they went to the LS2 so I think its got a lot of good things in it to make good power. Basically 65KW over the original 220KW LS1 engines from 1999, which is a 30% increase!
Here is the cut off table with my tune overlayed on the tune as recommended by the dyno dude. (Just change fuel from 12.6:1 to 12.5:1 at max torque)
So thats it for now. No more updates till I get some 0-60 or 1/4 mile times... or I get my extra goodies on.
The guy was very helpful and didnt mind me digging my laptop out and hooking myself up. On his advise Im now at 12.5:1 at max torque, which gained me 3bhp and 2ft/lb over my tune.
I basically overloaded their dyno as you can see my power run is cut short. I will try somewhere with a beefier dyno next time. I think I can make up more power with my LS6 intake and a new otrcai (Over the Radiator Cold Air Intake), plus run some high 98 octane fuel. Im also running cats still. Anyway peak power is normally aroung 5500rpm my run was cut short under 5200rpm so I wont know till the next time where we are at. Indicated flywheel power is 362bhp with 364ft/lb this is because the dyno measures trans loss on the overrun, apparently pretty accurate.
So I think for now Ive got things about as good as Im going to get them unless I retune for 98 octane. I think Ill just leave things be until March when the cam, intake and injectors all get changed then retune for 98 octane too. Im hoping for at least another 50-75bhp. Apparently the LS6 intake is worth 20bhp itself, plus maybe 10 for the fuel and 40-50 for the cam. We will see.
Injector duty was at 92% on the dyno so the new injectors will be required.
Tordne seemed impressed enough to request my tune and go looking for an HSV285KW base tune too. I had based my timing on the HSV table and found it very good. This was the last HSV LS1 engine before they went to the LS2 so I think its got a lot of good things in it to make good power. Basically 65KW over the original 220KW LS1 engines from 1999, which is a 30% increase!
Here is the cut off table with my tune overlayed on the tune as recommended by the dyno dude. (Just change fuel from 12.6:1 to 12.5:1 at max torque)
So thats it for now. No more updates till I get some 0-60 or 1/4 mile times... or I get my extra goodies on.
Friday, December 09, 2005
The cracked nut
Ok things seem to be going pretty well now.
I have totally axed PE mode as I was getting a "bog" when throttle went past its trigger position and enrichment started often at too low rev's. Now it comes on progressively after 85kpa richening up at max torque. Delco recommended a trigger of 80kpa rather than the factory 15kpa, but with the custom OS thats not required as I can command it with table B3647.
Ive been reading lots. Too much advance isnt good. In fact less advance in theory is good depending on what the power output is and at what point of the cycle it occurs. Afterall if you can spark after TDC on the power stroke and have max force expended on the downwards stroke then you are not wasting combustion pressures on slowing down the compression of the charge.
Here is my current spark table as of today.
So in summary its not important to get hung up on how much advance you can run. Your engine will be tuned to its fuel based on many aspects including its VE, combustion chamber design etc. Im running 22.5 deg at max torque around 4000rpm. It wont take any more without KR. In fact it might run even harder with a little less advance. What I did notice however is that after adding a few degrees at the lower end things have got very lively in the low and mid ranges, so much so that I requred a full 5% more VE across the board. I did take some timing off the upper end and some minor VE adjustments, however the engine is now running well.
Previously through the 70+ tunes that its now had in it I could pick out times when certain area's and parts ran well. Now I cant detect any part which needs improvement. Well not quite true. Id like a little more straight off idle..
I may richen up to 12.6:1 at WOT peak torque as Im running 12.8:1 and some recent reading suggests I should go a little richer and lean it to 13.1:1 above and below this point. Though near the redline and fuel cutout, I think a lean towards the high 12's would be more prudent there.
I dont think timing could be improved much more, subject to a dyno tune.
I must get some 0-60 times to see where I am now. In fact no more posts till I have done so :)
I have totally axed PE mode as I was getting a "bog" when throttle went past its trigger position and enrichment started often at too low rev's. Now it comes on progressively after 85kpa richening up at max torque. Delco recommended a trigger of 80kpa rather than the factory 15kpa, but with the custom OS thats not required as I can command it with table B3647.
Ive been reading lots. Too much advance isnt good. In fact less advance in theory is good depending on what the power output is and at what point of the cycle it occurs. Afterall if you can spark after TDC on the power stroke and have max force expended on the downwards stroke then you are not wasting combustion pressures on slowing down the compression of the charge.
Here is my current spark table as of today.
So in summary its not important to get hung up on how much advance you can run. Your engine will be tuned to its fuel based on many aspects including its VE, combustion chamber design etc. Im running 22.5 deg at max torque around 4000rpm. It wont take any more without KR. In fact it might run even harder with a little less advance. What I did notice however is that after adding a few degrees at the lower end things have got very lively in the low and mid ranges, so much so that I requred a full 5% more VE across the board. I did take some timing off the upper end and some minor VE adjustments, however the engine is now running well.
Previously through the 70+ tunes that its now had in it I could pick out times when certain area's and parts ran well. Now I cant detect any part which needs improvement. Well not quite true. Id like a little more straight off idle..
I may richen up to 12.6:1 at WOT peak torque as Im running 12.8:1 and some recent reading suggests I should go a little richer and lean it to 13.1:1 above and below this point. Though near the redline and fuel cutout, I think a lean towards the high 12's would be more prudent there.
I dont think timing could be improved much more, subject to a dyno tune.
I must get some 0-60 times to see where I am now. In fact no more posts till I have done so :)
Sunday, December 04, 2005
Book fest
Just got my book by Jeff Hartman, basically an MIT text book for Advanced Mechanic students. If you like differential calculus you will love this book. Its a nice 600 page tomb.
Lucky the book uses the maths to demonstrate the text, though at times I think it just gives up and explains things with long physics formula. Anyway very interesting so far. That will keep me busy over the holidays.
Anyway, my tune continues to improve. Im not convinced with "Lean Cruise" and have reduced the factory lean out by 50% as I had to put my foot down quite a bit to get it to maintain cruise speed. This was backed up by some comments from Delco at chipmaster in oz, an amazingly helpful pro tuner who seems to live and breathe GM PCM's. I understand he wrote some of the code for EFIlive.
Ive left DFCO on as I like the engine braking it creates. I also wiped out PE mode by setting map to 110kpa. I will use table B3647 to command enrichment instead and see how that goes. The main reason for this was that PE came in at 64% Throttle and I could feel the engine slump at this point. I was assuming that it was PE cutting in. Either that or the richer fuel.. or maybe lower spark advance. Anyway stage 1 test is to see if turning TPS and PE off makes a difference. If not Ill look at the enrichment settings. Basically 13:1 going to 12.8 at max torque then back to 13:1.
My commanded fuel is more gradual, though ramps to the same settings.
So Im summary my low end and mid range feels great. Im not so happy with the higher RPM range and believe it to be either PE or spark that is the cause. I got a little KR around 0.60g/cyl and 4000rpm, so have pulled timing there down to around 26deg.
More updates once I see how the recent changes go.
Im starting to read up on idle tuning in anticipation for some tuning action when the new cam comes in.
Lucky the book uses the maths to demonstrate the text, though at times I think it just gives up and explains things with long physics formula. Anyway very interesting so far. That will keep me busy over the holidays.
Anyway, my tune continues to improve. Im not convinced with "Lean Cruise" and have reduced the factory lean out by 50% as I had to put my foot down quite a bit to get it to maintain cruise speed. This was backed up by some comments from Delco at chipmaster in oz, an amazingly helpful pro tuner who seems to live and breathe GM PCM's. I understand he wrote some of the code for EFIlive.
Ive left DFCO on as I like the engine braking it creates. I also wiped out PE mode by setting map to 110kpa. I will use table B3647 to command enrichment instead and see how that goes. The main reason for this was that PE came in at 64% Throttle and I could feel the engine slump at this point. I was assuming that it was PE cutting in. Either that or the richer fuel.. or maybe lower spark advance. Anyway stage 1 test is to see if turning TPS and PE off makes a difference. If not Ill look at the enrichment settings. Basically 13:1 going to 12.8 at max torque then back to 13:1.
My commanded fuel is more gradual, though ramps to the same settings.
So Im summary my low end and mid range feels great. Im not so happy with the higher RPM range and believe it to be either PE or spark that is the cause. I got a little KR around 0.60g/cyl and 4000rpm, so have pulled timing there down to around 26deg.
More updates once I see how the recent changes go.
Im starting to read up on idle tuning in anticipation for some tuning action when the new cam comes in.
Friday, December 02, 2005
Nice
Still lots to learn, but a few things are starting to fall into place now.
My new (well HSV derrived) spark table was fine, no knock retard at all, so I merged a little more hardcore Corvette table in. I got a tiny bit of knock, but only at 4000, that was with some WOT runs, so that was cool, basically at Max Torque, where apparently its good to run more fuel. Fuel at that point should be sitting at about 12.8, maybe I should drop it to 12.5.
There is a discussion on efi101.com forum about more timing and more fuel vs less timing and less fuel, the consensus for performance appears to be that slightly leaner with less timing is good. So Ill pull some timing for now and see how we go.
Just as a reminder of how far Ive come I found this henous old VE error lable, using LTFT readings. I guess its not a million miles out, but its certainly all over the place. Rich down low and lean up high. I think if I have smoothed it out heavily and worked on it, it would have come right... Which in fact it did with some assistance.
I was commanding 14.63 and STFT was trimming nicely yesterday but as I have my LC-1 in as NB02 the signal isnt quite 100% the same, it tracks closely, but in the end one bank was reading like 6% different than the other. I thought this might not be good as they might be fighting against each other especially if the LC-1 was switching at the wrong point. So Im back to a non commanded 14.7 running soley off the VE table. Now getting that to track acutal is much more of a challenge. STFT were running an average of 2% out, so things arnt that far out. Each time I adjust 1% it swings the other way, so I think I might mess with IAT modifier or something else other than the VE table.
The car runs like a psycho now, light throttle causes nice acceleration which starts peaking a little over 4000rpm, it still pulls to the red line, but its not really worth it as the fun is done. My new cam Im sure will address this minor issue. Then the tune can start all over again!
So now Ive just got a little more playing around with the timing then most things will be right on. I dropped my idle to 625 the stock HSV is 640, so the timing must speed up low rpm operations and allow a much reduced idle. Tordne's idle was 900, so I suspect he can find more power in his spark table. He has said as much as he is now running a modified Corvette table.
The joys of not having a dyno to create a properly mapped spark table. Perhaps once I get the cam in I will pay for some dyno time to dial in a good spark map.
My new (well HSV derrived) spark table was fine, no knock retard at all, so I merged a little more hardcore Corvette table in. I got a tiny bit of knock, but only at 4000, that was with some WOT runs, so that was cool, basically at Max Torque, where apparently its good to run more fuel. Fuel at that point should be sitting at about 12.8, maybe I should drop it to 12.5.
There is a discussion on efi101.com forum about more timing and more fuel vs less timing and less fuel, the consensus for performance appears to be that slightly leaner with less timing is good. So Ill pull some timing for now and see how we go.
Just as a reminder of how far Ive come I found this henous old VE error lable, using LTFT readings. I guess its not a million miles out, but its certainly all over the place. Rich down low and lean up high. I think if I have smoothed it out heavily and worked on it, it would have come right... Which in fact it did with some assistance.
I was commanding 14.63 and STFT was trimming nicely yesterday but as I have my LC-1 in as NB02 the signal isnt quite 100% the same, it tracks closely, but in the end one bank was reading like 6% different than the other. I thought this might not be good as they might be fighting against each other especially if the LC-1 was switching at the wrong point. So Im back to a non commanded 14.7 running soley off the VE table. Now getting that to track acutal is much more of a challenge. STFT were running an average of 2% out, so things arnt that far out. Each time I adjust 1% it swings the other way, so I think I might mess with IAT modifier or something else other than the VE table.
The car runs like a psycho now, light throttle causes nice acceleration which starts peaking a little over 4000rpm, it still pulls to the red line, but its not really worth it as the fun is done. My new cam Im sure will address this minor issue. Then the tune can start all over again!
So now Ive just got a little more playing around with the timing then most things will be right on. I dropped my idle to 625 the stock HSV is 640, so the timing must speed up low rpm operations and allow a much reduced idle. Tordne's idle was 900, so I suspect he can find more power in his spark table. He has said as much as he is now running a modified Corvette table.
The joys of not having a dyno to create a properly mapped spark table. Perhaps once I get the cam in I will pay for some dyno time to dial in a good spark map.
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