After fitting the exhaust I was logging fuelling and spark. No issues with spark. But I noted O2 was running lean around 2000rpm then from 4000rpm on.
Hmm, so to adjust the maf flow air model, or do things properly and tune the virtual ve polynomials first.
Well it didnt take me long to decide to go straight to mafless. I know I need to remove the maf due to the potential restriction it represents. But stage 1 was to leave it in place and just fail the maf in the ECU.
This basically entails telling the ECU that any response from the maf signals a failure, rather than the default extreme values etc.
Still losing 5kpa air pressure somewhere, but at least now the tune is in place to allow maf removal without issue.
So first logging showed fuelling to be out by 7% over around 3500rpm and much the same at lower RPM.
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| Fuel variation from VVE |
This makes sense that most gains are at the upper RPM range. So next is to check throttle is opening properly under throttle and remove the MAF..
..Yay, mafless, BUT!
kpa still reads off 4kpa! Well I was told that would be the case. But seeing is believing.
So maf can go back in, though now its tuned mafless, maybe it will remain out to allow for future changes.
Geway, a fellow Kiwi, who has a ported LS3 and throttle said he was running 100kpa at WOT with a large cam. Given the MAP sensor is located right behind the throttle Im going to need to look at that. Indicated throttle is only 83% the VXR8 shows 88% so Im now wondering if the throttle is fully opening.
I would not have thought the throttle or intake were a restriction stock. Logic says the throttle is not opening 100% so thats the next port of call.
So in summary now mafless, but no new gains other than from the exhaust and adjusting the base tune to take the exhaust changes into consideration.
Also because I have now thrown a spanner in the airflow model, all future calculated torque numbers will only be relevant to this new baseline. So Ill have to go to Surrey Rolling Road for a proper comparison.
