I am currently tuning my car and noticed something that I would like an opinion on. I did a second and third gear pull and noticed that at the same RPM in each gear the AFR is about .1-.2 richer in third gear.

 

Load on engine is greater at higher MPH due to drag(wind). So that is what you want and is a good thing. did GM place in bin PE enrichment specific to gear? Mybe but I only have experience with 7747 on that and I dont believe it was present.

 

Thanks for the reply, I figured it was normal but not sure I 100% understand. I understand that the load would be greater, but from the ecm perspective, it appears to be the same as the 2nd gear pull.
That would be interesting if there was a table/constant that would compensate for this. Which gear should I target my AFR at for best power? 2nd gear and have 3rd a bit rich or 3 and have 2nd a bit lean?

 

12.8/1 is a good #. Reference the A/F to color of spark plug.

 

At the moment it appears that my motor likes about 12.5-12.6 for best power. The issue is that once it hits third it creeps to about 12.3-12.4 and I know I am giving up power. Probably not enough to worry about, but if I can correct this I would like too.
What I might do is tune 3rd gear for 12.5 so that second will still be under 12.8