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Title: This makes absoolutely no sense! Post by: carroll1992 on May 04, 2014, 09:22:55 AM Ok so the car in question is a 2005 Audi A4 2.0 TDI 140 (BLB Engine)
I sold the car and on the way back home the lad complained of it bunnyhopping, so he took it to a garage they fitted a new maf. Next day same issue just getting worse, so I have swapped back for now. Just replaced the EGR valve with a brand new one(The old one had snapped, flap no longer connected to rod). Still the same issue. Now this is where it gets complicated! With the EGR plugged in, the car idles rough, cuts out, plooms of black smoke out of the back, barely drivable. (all of the typical EGR symtoms) With it unplugged the car drives fine. Also with the EGR plugged in and the MAF unplugged it drives fine. Now the confusing part, regardless whats plugged in or not, on vagcom the Exhaust Gas Recirc (actual) and Mass Air Flow (Actual) are identical values. (With the EGR unplugged the values stay fixed at 550mg/str if I remember correctly. With it plugged in it is identical to the MAF (actual) which is obviously a long way off what EGR (spec) states which causes it to run the way it does. I assume these values being identical aren't normal and whats causing the car to run the way it does, what could the problem be? Spent all day trying absolutely everything I can think of! Any help or suggestions would be greatly appreciated! As far as I know the car hasn't been remapped so it should be running the standard map and was running perfectly fine a few days ago. Title: Re: This makes absoolutely no sense! Post by: carroll1992 on May 05, 2014, 05:46:09 AM Quick update, ive done some output tests on the new EGR, seem to be working fine. My guess is the garage have fitted the wrong maf? Could this be the cause? At idle the maf reading I well over 1000 and decreases as the rpm increases?
Title: Re: This makes absoolutely no sense! Post by: nyet on May 05, 2014, 11:14:19 AM Big intake leak, bad maf, bad/shorted maf wiring, wrong maf.
should be trivial to debug. have you logged maf voltage yet? Title: Re: This makes absoolutely no sense! Post by: carroll1992 on May 07, 2014, 04:36:40 PM Big intake leak, bad maf, bad/shorted maf wiring, wrong maf. Thanks for the reply turns out it was the wrong MAF fitted, cars running much better now but keeps going into limp mode due to overboost. Think its either sticky veins or map sensor.should be trivial to debug. have you logged maf voltage yet? Title: Re: This makes absoolutely no sense! Post by: nyet on May 07, 2014, 10:01:17 PM overboost is usually due to bad tune or torn wg lines, not map related.
Title: Re: This makes absoolutely no sense! Post by: ddillenger on May 07, 2014, 10:05:09 PM overboost is usually due to bad tune or torn wg lines, not map related. Not necessarily on diesels. Most common issue is a faulty MAF, then intake coking from the EGR, then the VGT veins in the turbo sticking. Title: Re: This makes absoolutely no sense! Post by: _nameless on May 12, 2014, 08:48:59 PM Thanks for the reply turns out it was the wrong MAF fitted, cars running much better now but keeps going into limp mode due to overboost. Think its either sticky veins or map sensor. log block 115 this is requested boost vs actual Title: Re: This makes absoolutely no sense! Post by: ddillenger on May 12, 2014, 08:52:37 PM log block 115 this is requested boost vs actual On a diesel? I think on mine it's block 005 or something. Regardless, when those things overboost it's one of three things: MAF Carbon Sticky VGT |