I don't know why but those dyno guys programmed my car to a 12:1 air/fuel ratio past 3000 RPMs...That's a tad too rich for me. This happened last year and I didn't notice it til now cuz I never took a good look at my dyno plots, and back then I knew very little about tuning so I didn't keep my eyes on their work too much.

Could somebody give me a brief walk-through of how to lean things up just a bit? I know I need change the settings to read less air than it was previously programmed to "read", but what buttons do I press on this thing to re-do the settings? Sorry I don't have my instruction book.

Any help appreciated, thanx!!!

 

Its a percentage value at each point... i.e. if he leaned it out, it would say -10% or something at the specific RPM points you have. If you wanted it leaner, you'd decrease it further, to say -15% or -20%. That said, I would NOT recommend doing it. The AFC needs to be retuned ON a DYNO! If you lean it out too much, you can kiss you motor goodbye... and you can't just lean it out by -5% across the board... it doesn't work like that... each point can require different levels of adjustment. You best bet would be to either remove it, or take it back to another dyno and have them retune the AFC. That or go buy a Wideband O2, have it installed, and tune it on the street... but that still isn't the greatest idea... though its actually somewhat better as its real world conditions, not stationary air dyno runs...

 

Good point that it should be tuned on the dyno, however, I do have my baseline dyno (before tuning) complete with air/fuel ratios and my corrected dyno (after tuning) with air/fuel ratios to use as references in deciding what is best. If I do a little math, I should be able to tune it perfectly, hypothetical example:
Let's say for my baseline run, my car was at an 11.5:1 air/fuel ratio at 4600 RPMs. What I'd do is calculate how much less air the PCM needs to read, so that I'd have a 13:1 ratio, which would be about -12%. I'd also look at the original tuning the guys did to confirm that their numbers match the mathemtical formula I am using.