Back on topic- here is a screenshot of a log from someone I'm tuning. He's OEM turbo's with PI on full E85. Factory coils with 0.022" gap and we just got him to around 21psi (pretty much maxed factory TMAP). His HPFP is 1500psi or higher, LPFP is 70psi+, no timing corrections, fuel trims generally good without significant deviation, AFR is flat on all previous logs around 12.2:1 or so. Stock turbo car in great shape with ~30k miles it logs great.
With the higher boost on this map, he encountered a misfire. Half way through the pull, he got a code for Cylinder 2 misfire. It was during a datalog so this is a picture of what happens with a misfire with PI, with everything else running perfectly:
View attachment 5723
You can see the initial misfires in bank 1 (housing cyl 2), circled. In a misfire, the air doesn't combust and shows as a lean spike. After a few of these, the car throws the code and goes into open loop, seen when fuel trims both go to zero. This causes an E85 car to run lean generally, as seen by both banks being much leaner than target in the 12's. But, since cyl 2 is shut off fully, you can see bank 1 is much leaner than bank 2. 14:1 vs 18:1, and cylinder 2 is likely MUCH leaner than that, since PI is still flowing.
Now is this dangerous? Doubtful for this car. Full E85 at that lean of a mix is probably not going to ignite to begin with, especially with lowly stock turbo's. But make this 28psi with hybrids, an E50 mix, or any other set of conditions and I would be a little worried about this. The PI makes the other 5 cylinders a little safer during the open loop event, but not the offending cylinder.
Any other ideas? I've seen this a few times. I do believe it has claimed at least 2 or 3 motors of those really pushing things, maybe more. I do not say this to scare people from PI... just the way I interpret the nuances of many logs I've seen. 98% of the time PI works great, it's a cheap and effective solution etc. Stay away from misfires and you're good.
