Hesitation at WOT, new WB and GM MAF

Ev0six · Jan 25, 2007, 11:21 PM

I recently installed GM MAF and PLX M250. I have PLX selected but wideband readings are way off. At wot i have a a/f of 12:1, at idle above 16:1. Even though its not accurate, going the old school dsm of reading of o2 voltages would say that i'm running rich. Can a leak in the exhaust cause the readings to be off? The attached file is the 3rd log i've done so far. All 3 runs have the same hesitation at 6k rpm. The car ran perfect before and was doing a rough tune basing on o2 voltages (0.92v) and the dyno graph.

tlcoll1 · Jan 27, 2007, 10:24 PM

Is the ECU+ installed on the Galant VR-4 or the EVO VII?

Tom

Ev0six · Jan 28, 2007, 04:09 PM

Evo.

tlcoll1 · Jan 28, 2007, 10:59 PM

It does look like you're running rich across the board. At idle, your front O2 sensor signal should be flipping back and forth between 0 and 1 volt or so - if you look at your fuel trims, I'm guessing they'll be pegged.

I would say to try to tune out the richness, starting by fiddling with the injector scaling - maybe set it to 600 now, 550 stock, and go from there. It's possible that production variances between the GM MAF and your stock MAF are making the problem happen, or maybe the EVO7 MAS calibration is different than the EVO8 calibration that the ECU+ is setup for.

Tom