Rough idle on cold start 2.0 FSI

Started by benpaul12, January 19, 2017, 12:07:09 PM

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benpaul12

Hey everyone, happy to be back in a VW after a few years of BMWs!

Bought an '05 Golf GT 2.0 with 68k on the clock - day after picking up from the dealer the engine light came on, it also had a rough idle following cold start. Following that, everything was fine. I had suspicions that because I put 98 in after it would've been running on dealer's 91 fumes...

Took it back (under 3 month warranty), cleared knock sensor fault, engine light gone. Idle on start gone (although this would've been a warm start). Started today and rough idle on start reappeared. Drives fine and idle issue does not exist, no engine light.

After looking around on forums, this is a common problem and many have found it hard to diagnose or pinpoint. I am in a slightly tough position because if the engine light isn't on, and this is only replicated at cold start - I may have a hard time with the dealer. I will be returning it, prefer to be armed with a bit of knowledge.

Some suggestions on forums is that fuel may be an issue. Perhaps 98 is too high? Or Mobil 98 is of bad quality? Should I be using 95 - or even 91?

Anyone has any advice or ideas around this issue?

slowmo

Some issues with MAF won't necessarily throw up an error or CEL.

Alternatively check the coil packs

Did the dealer run a scan to check other fault codes? Some scanners may not be as good if they are only generic.
Current: 2004 MK4 R32 3-door NZ New DBP

Past: 2010 MK6 GTI / 2013 Nissan Leaf LOL / 2007 B7 RS4 / 2006 MK5 R32 / 2005 MK5 GTI / 1998 MK4 GTI / 1997 B5 A4 MTM

benpaul12

They didn't tell me what other codes came up. Will be asking more questions, and be taking it back next week until they fix it.

I wonder if with a few more rough starts the engine light will throw again.

urs6v8


benpaul12

I'm not sure, only owned the vehicle for two weeks now and no service history.

benpaul12

Engine light back on on the drive home. Good, now there's something clearly wrong for the dealer!

yusuf

Do you have the 2.0Fsi Non turbo engine?
That's what I have in my Touran, and I am trying to track down a lumpy cold start idle for a long time.
I do not have a CEL.
Do let us know what your one turned out to be, please.
1996 Volswagen Vento VR6 - Toy
1998 Audi A3 1.8T - Daily
2005 Volkswagen Touran 2.0FSI - Family

JPK

We had one of these engines a while back. It could be some of the emissions gear but GLIDN on here is probably the best one to answer those questions.
It is really best to scan it first as you could be replacing unnecessary parts.

It will probably be one of the below. Replace in this order. You can scan it to see which cylinder is misfiring.

1. Change coil packs (regardless of them being different part numbers in some cases, the coil packs for the GTI AXX engine will work and are much cheaper).
2. Change spark plugs (probably not this)
3. Change injectors

We had all 3 on ours before the issue was resolved. Could also be the MAF but i haven't personally had any issues with the MAF on the two FSI engines we have had.
A3 8P Sportback 2.0T DSG
- Progress Diary -

Worms

There is a bunch of places they can have vacuum leaks.

What engine codes? the ones that have both stratified an homogenous modes seem to have worse cold running if there is a leak. They also strugggle more when the intake fills up with crap, because of the direct injection.

My 2006 Touran had a cracked dipstick tube, and a brittle/cracked breather pipe. It was a 2006 NZ New BVY engine, which had homogenous only, and it had a very slight irregular missfire when cold, but only after changing from high idle, to normal. I only found the leaks when i was removing stuff to get the engine out.

benpaul12

Picked up the car today, the NOX sensor was replaced and they changed the coils. Car feels much happier.

Hoping this is it!

benpaul12

Well the NOX sensor clearly wasn't the issue, misfired again this morning with flashing engine light. Back to the dealer, "coils" they're guessing! Fun times :)

Worms

Didn't they change them already???

They might be barking up the wrong tree anyway.


It's probably worthwhile betting it scanned with VCDS by someone to see what the real codes are. Anything else is like trying to piss up a rope.

benpaul12

#12
I believe they did the coil(s) only on the one(s) reported to be misfiring.

Filx

I think mildly rough idle at cold start can be a sign of carbon deposit build ups.
FAIL - First Attempt In Learning

benpaul12

Quote from: Filx on February 17, 2017, 11:00:37 AM
I think mildly rough idle at cold start can be a sign of carbon deposit build ups.

Yeah this has seemed to be a regularly attributed reason I've noted on a few forums with the FSI engines (in Audis too) one example here: http://forums.vwvortex.com/showthread.php?5702032-FSI-Carbon-Build-Up-Removal-Benefits-Fact-or-Fiction

Many say that the buildup clean only makes a difference to the cold-start issue, and isn't something that changes performance. I will look at getting this done if it's a problem which worsens, but at the moment we're treating it as normal.

Another coil has been replaced, car seems to be running better now. Hoping, again, that this is it.

Not_Sean

Going to be keeping a eye on this, my A3 doing the same thing, only on cold start, but once its warmed it drives like a champion and the idle is just a little lumpy for a few mins than its back to smooth
2004 A3 2.0 FSI

yusuf

benpaul12 did the coils sort out your issue entirely?
1996 Volswagen Vento VR6 - Toy
1998 Audi A3 1.8T - Daily
2005 Volkswagen Touran 2.0FSI - Family