Rough idle and low rpm

[NickyR1983]

I bought an audi a3 1.6 petrol in October last year. Since I bought it, the car seems to suffer from a rough idle. It idles around 600 rpm and this causes the car to shudder quite a bit when sitting stationary.

In the past few weeks the car has also started shuddering when changing gear, feels as if its about to stall.

In addition there was a backfire from the exhaust when starting the car up.

I've had the car to a local mechanic who said it seems to have a slight misfire but no fault codes showed up on his machine. He said it could be a million and one things.

Anyone any ideas as to what it could be? Any help would be greatly appreciated.

[Alexgam2007]

Hey I have an 1999 a3 with the exact same problems lumpy and jerking at idle and almost like back firing from the exhaust with no fault codes I tried new plugs/leads and a coil pack and fuel filter but still no better hoping someone can help as I'm now lost!!!!!

[Col]

It is most likely to be the electronic throttle body.

Do a search to find lots of information on this common problem.

Quite simply;

It gets gunked up with an oily residue.
This residue prevents the throttle flap from seating.
Correct seating is very important as the ECU minutely adjusts the flap angle to provide 'just' enough air at idle.
The movement is small and any gunk can interfere and cause problems.

To remedy, an easy DIY job for the first bit;

Remove the throttle body and clean the gunk out.

If your lucky that will sort it.

If your not so lucky, it needs to be electronically aligned with someone with diagnostic equipment, look in the vagcom users sub forum on here who could do this for you for a case of beer. (A case of beer being about £16 vs £ one hundred and twenty thirty million plus VAt sir and we need the car for two days and you need to sort out a lift etc etc).

If your really unlucky the throttle body is knackered and you will need a new one plus the electronic alignment.


Other than that, could be a split vac hose or breather hose, do you both know what your engine codes are ?

[HAWKS]

As above.
Throttle body cleaned an you should be sorted.
It was the same on my 1.8T.It was lumpy an it would stall when on full lock.

[Alexgam2007]

Hi guys thanks for the input I took the throttle body off and cleaned runs far better when revved but unfortunately won't idle now so gonna get someone to align it and hopefully will sort the issue will update as soon as I have any joy:biglaugh::biglaugh::biglaugh:

also forgot to add that it's an akl engine

[Col]

Look here and pass it on to whoever does the alignment

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