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Rough idling Audi A4
I have an ageing (53 plate, 120,000 mile) Audi A4 1.9 TDI. It has been a great car but over the past few months the idle has gone "lumpy" intermittently.
Above idle it runs smoothly, there is no loss of power and there has been no increase in fuel consumption. The local Audi dealer has fitted a new EGR valve and a new electronic engine mount but (several hundred pounds later) the idle problem is still there.
They have now given up on it saying that any further work will be "very expensive". There are no faults showing on the diagnostics and all the injectors are working within tolerance. They say it's unlikely to be a Dual Mass Flywheel problem because there is no noise on pull-away or when turning off the engine and it does not smoothe out when the clutch pedal is depressed.
They say it is possible that there is a problem with the wiring loom in the head but can't rule out either the loom or the DMF without major work.
I have had enough of spending over £100 per hour for the Audi main dealer to work on it unsuccessfully and I'm reluctant to place the car with someone else who will start from scratch and charge lots of money just to tell me that there are no obvious faults. Can you please advise me how I can narrow the problem down so that I can get it fixed without spending ever increasing amounts of money on an old car?
Above idle it runs smoothly, there is no loss of power and there has been no increase in fuel consumption. The local Audi dealer has fitted a new EGR valve and a new electronic engine mount but (several hundred pounds later) the idle problem is still there.
They have now given up on it saying that any further work will be "very expensive". There are no faults showing on the diagnostics and all the injectors are working within tolerance. They say it's unlikely to be a Dual Mass Flywheel problem because there is no noise on pull-away or when turning off the engine and it does not smoothe out when the clutch pedal is depressed.
They say it is possible that there is a problem with the wiring loom in the head but can't rule out either the loom or the DMF without major work.
I have had enough of spending over £100 per hour for the Audi main dealer to work on it unsuccessfully and I'm reluctant to place the car with someone else who will start from scratch and charge lots of money just to tell me that there are no obvious faults. Can you please advise me how I can narrow the problem down so that I can get it fixed without spending ever increasing amounts of money on an old car?
Asked on 8 July 2012 by snozzleman
Answered by
Alan Ross
Problem is that it could be a number of things, and with the diagnostic not showing anything it makes it rather difficult to identify.
Check to see if your VIN number is 8E3A301497 onwards, if so it may be worth checking the Fuel Pre heat valve, this is a known fault on your model and gives poor driveabilty/jerking during engine warm up up to speeds of 30 to 45mph. A modified fuel pre heat valve is the solution.
Other than that check the condition of the fuel filter.
Also the next thing we would check would be the ECT (engine coolant temp sensor)and then the CKP (crankshaft position sensor) both of these could result in bad idling.
Check to see if your VIN number is 8E3A301497 onwards, if so it may be worth checking the Fuel Pre heat valve, this is a known fault on your model and gives poor driveabilty/jerking during engine warm up up to speeds of 30 to 45mph. A modified fuel pre heat valve is the solution.
Other than that check the condition of the fuel filter.
Also the next thing we would check would be the ECT (engine coolant temp sensor)and then the CKP (crankshaft position sensor) both of these could result in bad idling.
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