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Author Topic: MK5 TDI rough idle  (Read 3353 times)

Offline mohammed10

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MK5 TDI rough idle
« on: January 16, 2014, 08:59:06 am »
Hi guys, got a bit of a problem with my 56' plate 1.9 TDI. It's got just below 52k on the clock and it's always been serviced on time, by me anyways.

Bought it in July 2012, couple of days later felt the idle was a bit lumpy on startup, wasn't too bad and went away once it was driven, so didn't really take notice. I must mention that on the first service I did when I changed glow plugs etc. the mechanic servicing my car said the glow plug kept spinning in cylinder 4. Got it taken out and had to get the head re-threaded.

Got the car remapped by Revo in November last year, to approximately 145 bhp. Drive the car sensibly to save fuel, always feed the power in and never boot it from a low RPM.

Noticed the engine started shaking quite vigorously on startup.
It goes away when I'm driving, but comes back once I've turned the car off and back on again.
Did a diagnostic read on VCDS a while ago and got a cylinder 4 misfire (intermittent) code.
Cleared it and didn't see the code back again when I did another check,

Turned out it was a faulty injector, car started smoking real bad over the last few days and it seems the injector was dripping fuel rather than "spraying".
Got the injector loom changed first, didn't fix anything, so changed the injector and paid twice for labour

So anyways, the harsh vibrating has now gone, but i'm left with that same slight rough idle that occurred when I first got the car.
It just seems slightly lumpy. So called up revo to ask if the fueling could need adjusting,
They advised that it definitely wouldnt be anything to do with their map, and seems like the MAF sensor or an air leak.

Cleaned the MAF sensor and sprayed some stuff around the joints of all the pipes and couldn't find anything.

 Genuinely stumped right now

Any help is appreciated, thank you.

Offline doylebros

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Re: MK5 TDI rough idle
« Reply #1 on: January 16, 2014, 09:16:11 am »
Just a thought.

Not uncommon for the dual mass flywheel to cause erratic idle (if left ticking over for any length of time) yet drives perfectly well!

Offline mohammed10

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Re: MK5 TDI rough idle
« Reply #2 on: January 16, 2014, 09:26:16 am »
Hi mate,

cheers for the reply.
I was reading up on google, that it could possibly be the DMF.
Is there any other way to tell if it has definitely gone?
Or is it just one of those trial and error things?

Cheers