tjwong

We are working on Red99's Maggie equipped A4 C5 and we are seeing a strange fuel trim issue when in closed loop. It appears normal to about 2000 RPM while driving in 3rd gear. The fuel trims will run slightly negative on both banks, as you increase engine and vehicle speed to say 2500 RPM the fuel trims beging to skew, with bank one remaining at about -4 to -6 while bank 1 will start climbing positive and sometimes pegging at +25%. I have verified that it is indeed going slightly lean causing the PCM to enrich, I will reset the fuel trims to 0 and I can see that the AFR on the right bank goes slightly lean to 15.7.

So far we have swapped the fuel injectors from right to left, swapped plug wires, and inspected the spark plugs, all seems well......anyone else run into this strange problem as it has us bewildered

T/A KID

iTrader: (12)

I know this is old, but did you ever find a fix??

Tuning with HP tuners and in CL I noticed bank 1 starts adding fuel slowing and goes up to +25% and bank 2 stays around 0% plus or minus a few percent.

I am thinking vacuum leak around the intake or headers, but can't find anything with spray? I changed 02's and still the samething on bank 1.

Any advice??