Audi 2.5 V6 Oil burner has lack of go
Discussion
My Audi has a lack of pull and runs out of steam.It has had 2 replacement mass airflow sensors and on my mates diagnostics is still saying low airflow,so we think it's an ECU problem or another sensor.We can hear the turbo spooling up,but there is ,what I guess something preventing the boost going to the inlet side.Anyone know anything about this fault.It's booked in for a rolling road next Wed,but if anyone could try and help in the meantime,thanks.
Have checked and cleaned aif filter and box.There is no audible sound of a leaking hose because of lack of air noise.One thing that is possible is wastegate but according to my mates diagnostic plug in,the mass airflow meter is still reading low air.This also explains it being smoky black from the exhaust on acceleration,as lack of air movement.Even after trying 2 new airflows.We think it might be the ECU not reading right from the airflow sensor and throwing the management into 'get you home mode' or i suspect the turbo not spinning up to give the boost.Probably aiming at the first one.Will tell all hopefully on Wed night after the rolling road session.
Air Mass Meter is probably the culprit. I believe it is a common problem on VAG diesels, and also on Saab (GM). My Saab slowly got sluggish, until it would have been quicker to push it out of junctions!
A new AMM should sort you out (turned my Saab back to a front tyre smoker, under provocation), although they are not cheap (apparently, mine was done under warranty).
HTH
Sparks
A new AMM should sort you out (turned my Saab back to a front tyre smoker, under provocation), although they are not cheap (apparently, mine was done under warranty).
HTH
Sparks
we're still not sure what it is.The guy we took it to in Thruxton,wants it for a couple of days.He checked over the usual things,we saw the turbo spinning up nice and free,just is lacking boost.the wastegate seems to actuate.He wants to go through the wiring and all sensors.We know the engine has been changed at some point,although Audi don't have that info on their computer ( we checked it's history before we bought it) even tho' it has a full Audi service history.Luckily the garage we got it from is picking up the bill.....Just a sod,because it's a nice car.Will let you all know as soon as we do.
deltaf said:
Its had 2 already! 
Could still be at fault. They are very fragile out of the car, so any rough transportation or being dropped can knacker them quite easily.
But I must admit to a bit of blindness, as I read the whole lot (I've made a fool of myself before
) but still missed the two replacement AMM. Good luck with fixing it though.
Sparks
Sparks said:
Its had 2 already!
Could still be at fault. They are very fragile out of the car, so any rough transportation or being dropped can knacker them quite easily.
But I must admit to a bit of blindness, as I read the whole lot (I've made a fool of myself before
Good luck with fixing it though.
Sparks
lolol i was only quoting what id read too mate!
we've had all the pipework apart from the airbox to the turbo.The maf sensor was inspected in bits.With all the pipework apart,we could see the turbo spinning up.Could well be a turbo problem with maybe the wastegate not closing properly causing the lack of boost,so bypassing the inlet.I suppose putting a pressure gauge on the inlet pipe to the manifold might give an inlet boost pressure.Being a diesel,should only give about 10-12 psi boost.
West tuning at Thruxton have had it in bits today.First thoughts were that the 'variable vane' turbo was at fault.Before that was stripped to bits,he found the 'map sensor' near the intercooler was not reading,so causing the fault.He bypassed that and sadi it worked well.Just got to wait 2 days for a sensor now.......
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