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Matt
Matt, Mechanical Engineer
Category: Audi
Satisfied Customers: 21989
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Audi a3 3.2 quattro dsg, 2004 esp light came on then when stopping

Resolved Question:

Audi a3 3.2 quattro dsg, 2004 esp light came on then when stopping at traffic lights still in drive the engine revs died and car stopped.
To move off again I had to rev the engine in neutral and quickly change to drive before the revs died off again.
Did this for approx 70miles then I stopped, turned engine off and back on then esp light went off and it's been ok since.
Any ideas on what could have caused this would be much appreciated.
Submitted: 1 year ago.
Category: Audi
Expert:  Matt replied 1 year ago.
Hello if you have an ESP light is staying on then this would indicate a fault with the stability system which can cut the power to the engine to try and reduce a skid that isn't actually occuring, as its just a faulty sensor The quickest route to repair is to have the car plugged into a diagnostic machine which will read off the fault code stored in the ECU (providing the light is still on at this point) and indicate which sensor has failed or whether the fault is more serious. However with ABS /ESP systems 99% of the time its a problem with one of the wheel speed sensors and I'd first check the connections at all four corners first for any signs of corrosion or chafed wiring.The sensor is located in the wheel hub so you'll have to remove each wheel in turn to inspect them all.Also check that the toothed wheel that the sensor points to is clean and free of any debris.you can check each sensor's function by plugging the two output wires into an AC voltmeter and spinning the wheel quite quickly, you should get a voltage signal that increases with rev's. Its possible that the fault is only a bad connection to one of the wheel sensors.This may be remedied by removing each wheel in turn and unplugging each sensor and cleaning the contacts with a squirt of electrical contact cleaner. Then refitting.
Customer: replied 1 year ago.
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Customer: replied 1 year ago.
The power to the engine didn't just cut off as I could keep it going in neutral by reving.
The revs would drop off once in drive as I could not rev without setting off.
The esp light is no longer on.
I have read numerous other posts on blogs and none have mentioned about wheel sensors.
I will take a look at what you have suggested.
Can you think of anything else that may cause this? MAF etc?
Customer: replied 1 year ago.
Unfortunately this does not seem to be the fault.Any other ideas would be appreciated.
Expert:  Matt replied 1 year ago.
Hello OK in that case lets move onto checking out the engine side, for the engine to die as you describe its likely that its not getting enough fuel and could be a lack of fuel pressure from the electrical pump at the tank. If the connections to the pump are corroded or damaged then the pump could stop at any time or could not be running at full speed. Check that its relay switches in and out and the relay contacts are clean and bright – replace the relay if in any doubt and do the same for the fuse,Ideally measure the pressure at the injector rail and if this is low check the pump as described and also consider changing the fuel filter as if this partially blocked this too will reduce pressure. if this is OK then this could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out and can also allow the engine to rev up when not desired causing rough running.As its a mechanical fault it tends not to turn on the fault light and you can sometimes hear a 'hissing' noise with the engine running. Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts. The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash/ignition point of gas is about 400°C so you need a naked flame or spark to se tit off and I’ve used this method for many years without incident.Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.
Expert:  Matt replied 1 year ago.
Hi
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