Lack of power & smoke

[wid77]

I have looked at other posts for help but not been able to find an answer to my problem yet.

I have a 2001 A4 with the 115bhp PD engine. Has done 190k but always been well serviced. Over last couple of months or so I have noticed a hesitation/sticking feeling when engine revs past about 1800rpm. It then seems to clear just after about 2100rpm. Something seems to hold the engine back if that makes sense. It will still rev through the full range though. Overall it lacks power and if I boot it I can make an impressive cloud of black smoke. I'm assuming the fuel isn't being burnt correctly.

I did take the car to an Audi specialist and he had a quick drive and look. Only fault he could find was a 'low boost' code but he said that he would need the car for a while to diagnose correctly. He did suggest it may be the egr valve. I removed this and fully cleaned it, put it back on correctly and the problem remains.

I use the car every day and it is still driveable but here is a definite lack of lower and my economy has dropped from about 42mpg to 36mpg although some of this may be due to the cold weather?

I am a bit strapped for cash at the moment (divorce, don't ask!) and need the car so have put off taking it back to the specialist but I will have to if I can't sort it myself. Can anyone advise what it could be? I'm thinking it may need a new egr valve or could it be the maf sensor? I'm only guessing though and could do with some pointers if possible?

Thanks.

[Crasher]

You need another code read to see if the boost code or any other code are still there. Anything else is guesswork that could easily involve changing parts that are not faulty.

[wid77]

Thanks Crasher. I will get it back to the specialist as have no code reader. Can i just ask though can a failing egr valve cause a 'low boost' code?

[Crasher]

If it was stuck open, yes, but if it was stuck open the engine would run like a pig and pour black smoke. A split EGR valve diaphragm could also cause 17964 by creating a vacuum leak which knocks the control system out.

[tets]

check the rubber hoses especially the 3" (approx) one coming off the top of the turbo - mine had a slight split around the clip which once changed cleared everything!!

cheers
Steve

[Brycie]

Split intercooler caused those symptoms in mine. That's something you can check visually.

[Crasher]

Split intercooler caused those symptoms in mine. That's something you can check visually.

I had one yesterday on a car exactly the same as yours Brycie (2007 though), even removed and cleaned on the bench the split was invisible, it only showed up under pressure testing.

[Brycie]

Oh right, fair enough. In my case the mechanic was able to just look down & see the oil lying on top of the intercooler which tipped him off to a split. I suppose it depends where the split is. Maybe worth a quick check, but I bow to your knowledge obviously Crasher.

[Crasher]

I bow to your knowledge obviously Crasher.

I would not expect anything less...

[wid77]

Bit late but just realised I didn't update this thread that I started! The problem on my car turned out to be a split in a rubber hose causing an air leak.


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