View Full Version : A little trouble shooting and maintenance help please - extreme tune

08-09-2007, 09:31 AM
Hello guys,

I have a 98 A4 quattro 5spd, 2.0 stroker, gt25 turbo, GReddy profec ebc, secondary bank of injectors in the intake that feed hi oct under hi boost, 3" exhaust, piggy back ecu mgmnt from SDS, Turbonetics wastegate, intercooler with custom plumbing (no leaks found) ONLY 33,000km's (about 20,505miles) on her with about 500 on a new rebuild (rings and stuff).... I can supply more info if needed.. but she sat in a garage for a number of years... clean and tidy, until I took her away.

Since putting a cpl hundred kms on her over the past cpl weeks, I have recently noticed my a/f gauge (not wideband) showing a lean condition under WOT and hi boost. When accelerating or if I stay out of boost, things are completely fine, open it up hard and it slowly goes step step step, down the gauge right into danger zone. I have not heard any knock or pinging... but hard to tell with the exhaust note. My a/f gauge is a custom, so I do not know what that means numbers-wise (info has been requested)... just red led's, red=lean. If I slghtly lift and get on it again it gets pretty close to normal again and sometimes does not lean out further.. and it has been leaning out <50% of the time when I get on it. I have been gentle around this situation, so my data acquisition is a little low... I have noticed slightly lower boost also, maybe 10lbs (where about 16 is norm).

Since getting the car a cpl months ago, I had to use some Torco to keep the boost tank from emptying.. I mixed it with local gas to get near my desired needs, octane wise (104)... but I have been setup with proper gas now, just haven't got it in yet.. both the main tank and boost tank had Torco since gas here is shite and she is tuned for 94 in the main, 104 in boost tank.

I am thinking either o2 sensor, air filter (it's dark, but not drrrty), fuel filter for the line feeding the secondary bank, or a fuel pump somewhere... I have friends who can vag com me, I suppose that would be a great place to start, I have not received any dash warnings (cel)... but does this sound familiar to any of you guys? Should I get the 'proper' gas in and see where things are from that point first? I know lean means low quantity, not quality... but ??

Thanks for any advice and hanging in to read my lengthy post here.