2002 3.0 Quattro, cold start idle issues

[Computageek]

Hi Guys,

I have a 2002(51) A4 3.0 Quattro Sport (Auto). When I start up at cold, the engine sounds awful. Almost as if there is a cylinder not firing. There's vibration through the car and the exhaust note sounds like the the car is "chugging". Revs are around 1200.

However......

Once it's had about 2 mins of running, the engine returns to a steady idle of 750-800rpm, but it's not as smooth as usual. The power in the gears feels a bit lacking, but nothing too drastic, just a bit less lively than I expect.

I have ordered a USB Cable and have VAG Software, but have ZERO clue how to use it anyway :)

Any thoughts would be most welcome.

Thanks
Pete..

[Hanny]

Not sure how far out I am but still new to Audi set ups but am quite experience with some DIY on other cars.

Am sure that one of the more experienced guys may be able to offer a better insight/solution if this is a well known fault/issue etc. How ever here are a few ideas that may be usefull:

The symptoms that you have could be down to quite a number of things however there are some basic checks that you may want to have a look at:

From what you have wrote could be an indication that there is a fault with initial cold start and thus an airleak, EGR valve or O2 sensor.

1 - air vacum leaks: at the front of the engine there is a black plastic cover - it is clipped on, remove and have a look at the small rubber pipes - for condition and if they are holed.
2 - Im am not 100% sure on the VAG cars but others do show same sort of fault when one of the 02 sensors start to play up - on some the ECU uses the O2 sensor at start up and once warm uses an average reading from the MAF sensor once runing - so if your ECU has recorded a series of faulted readings from the MAF it may cause the lumpy idle once warmed up.

Other option is to connect your VAG-COM and start the engine then post on the forum so someone more familiar can identify from the readings.

Afraid thats all I can add for now as mentioned - new to the B6 3.0 engine.

[Computageek]

Thanks for the feedback. I tried the VAG-COM etc and there are no fault codes at all.

I took the car to AUDI and they said there is nothing wrong. However, now the cold weather is here, its worse than ever and sounds like a tractor for about 20 sconds on cold start up.

So, £80 less in the bank and still an annoying fault. :(

[Computageek]

So...... We now know the issues.

On Christmas day, travelling on the M11, poooooof. White smoke billows from exhaust, engine overheats quickly and a stop is necessary.

Six weeks later and the car is still at VAGTECH but they found the root cause of all my ills.

The block is cracked internally at cylinder 6. So, I'm now in the market for a replacement engine or a bottom end at least.

Damn!!

So far, not found a single 3.0 ASN engine ANYWHERE!