Idling problem mk4 gti

[Mdwalshy]

Hi all,

Had a problem for a while now with an idle problem, the car drives fine apart from bad mpg. The problem is when coming to a stop the revs will bounce below and around idle rpm.

I took the car to the garage to have it code read and got maf signal to low and coolant temp sensor so these have both been changed now, the car runs slightly better but still have the same idle problem. Had the car code read again and it's still shower maf signal to low. What other problems could cause the idle problem? 

Thanks
Mike.

[baxxy]

Could be a broken wire at the maff plug..... what model is it Gti or Turbo

[Mdwalshy]

It's a turbo on a v plate. Yeah never thought about that :-).

[mike1990]

It's a turbo on a v plate. Yeah never thought about that :-).

I've got the same problem mate, maf signal too low and revs just bounce around and the car shakes until you put revs down

[baxxy]

Could be an air leak as well or coil packs breaking down

[Mdwalshy]

Well if you find the solution let me know ;-). From what I have read it could be a number of things 2 of them being a blocked air filter or an air leak, so going to put a new air filter in today as it's needs doing anyway. The other thing I did was clean the throttle body which didn't help so if air filter doesn't change anything will have to check for an air leak. :-)

[mike1990]

Well if you find the solution let me know ;-). From what I have read it could be a number of things 2 of them being a blocked air filter or an air leak, so going to put a new air filter in today as it's needs doing anyway. The other thing I did was clean the throttle body which didn't help so if air filter doesn't change anything will have to check for an air leak. :-)

Will do

I changed the lambda sensor which i'm not sure if it works but no error has come back. Could be the MAF, although my crankcase breather pipe has completely split so unsure whether it's that aswell

[Phookit2]

I have exactly the same issue on a 99 turbo. Under load it's fine, idling it's bouncing. I have the digi climate control, so to add load switched air con on, stopped bouncing at idle now.. Eats petrol though.  Not had in in for code reading but will update when I do.
Fyi if you need to replace the maf, they are on auction sites for £35 for genuine items presently. Search and you shall find.

[Wazzzer]

Did they clear the codes when it was scanned last time

[Mdwalshy]

Yeah the codes were all cleared last time. Fitted the new air filter, the old one was bad and full of all sorts. The car has improved quite a bit but still has a bouncy idle so next I'm going to check all the pipes for splits or that might have come loose.