Cold idle stutter and twitching at low revs - 2.0 TSI Octavia vRS

[jaegarmaisteri]

Hi again

 

I have problem and my dealer doesn't no nothing. So, to symptoms. When I cold start the engine, revs goes normally to over 1000rpm:s and I hear this sound as it doesn't run with all sylinders and idle is irratic. Ok, the revs go down to ~800, it is normal. When driving, there is slight twitch now and then. This twiching appears always when I use "surface gas". Easiest to get it twitching, is to drive with cruise control and with speed of max ~60 kmh. Then the revs are under 1600.

 

All this goes away when engine warms. There is no fault codes. This takes about 5-10 minutes and then everything works fine.

 

I've runned with System Fuel Cleaner (Forte) for 3 full tanks.

I've tested also other petrols too. (95E10, 98E5 and Shell Vpower). Dealer suggested that I would only run with 98E5.

 

My VAG dealer has now done so far (what I know):

- Changed coilpacks and plugs

- Changed Control Unit for Fuel Transfer Pump (I guess this is nere the fuel tank)

- Changed Timing Chain and others relevance to it

- Changed Throttle Body

- Runned several diagnostics and nothing appears (no faults or misfires).

 

- They have done some other stuff too, but I havent got any bills, so I dont know exactly what. Propably cleaned something.

Ok, like I said, they dont have a clue where to find this problem, and so far the repair cost are atleast 1000€ for parts and same amount for the work (total 2k€).

 

I've read that some cases the MAF, Coolant Temp etc. could be also a problem. Please give me some suggestions.

Here is link to Youtube for a video about the sounds today after cold start today http://youtu.be/8Nt7vZHChw0

Car is inside a carage night time, and temp usually at winter time is +15'c. So it should not be related to outside fenomenoms.

[vonbeck]

I'd be tempted to remove the maf and try one off a car which is running ok if you can or clean the maf sensor with IPA fluid just needs a quick soak and leave to dry as it evaporates pretty quick

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[R8MXX]

Sounds like the issue I had with my TFSI which also affects the TSI.... Inlet ports coked up, could be worth checking...

 

Have a read of my thread on the issue... http://www.briskoda.net/forums/topic/273037-vrs-20t-fsi-stuttering-at-idle-and-on-acceleration-up-to-2000-rpm/page-2

[brad1.8T]

^^^ what he said.  You haven't said how many km you have but if it's over 50k then worth putting a borescope in through the inlet air temp sensor hole & having a look

[TB1]

PCV and Diverter Valve need replacing before you do anything else.

High/hunting revs are a sign the PCV is stuffed. Try removing the oil filler cap, if there's a strong vacuum or the engine doesn't stutter when you remove it then it needs replacing.

The stutter on light throttle is likely to be a split Diverter Valve.

These are both cheap and easy to replace before having to worry about things like coked up inlets.

[jaegarmaisteri]

Thanks for all the replys. I had my car at the local shop this friday, and they finally checked/measured the fuel nozzle. So, they found some missfire from nr.4. Already at the first time 1.5 month ago they changed coils and sparkplug for that nr.4 sylinder, when there were faultcode. Now they will open the manifold and change it. At same time they will also wash the engine. I hope this will fix the problem. I told them at the day one, to checke the nozzles, but nothing happend. Only answer I got was, "we will start eliminating possible causes from obvious places". I am pretty ****ed, if this is the reason. For grand total, this experience propably will cost totally 4k€, Let see how it goes.

 

EDIT: Kilometers are now over 90k.

 

EDIT2: So they were able to get some missfires from nr.4 sylinder. They said it wasnt easy, since the engine is hot quite quiqkly, and that basically fixes the problem. I seriously hope, this will fix the problem.

Edited 29 March, 2014 by jaegarmaisteri

[jaegarmaisteri]

My car has worked perfectly these past two days after the latest reparations. Now after couple of days, it looks like reason for my cold idle stutter was the #4 fuel nozzle. The intake manifolds were open, so it is also cleaned inside the engine. The engine sounds great now.

 

Thanks for all the suggestions thou.

Edited 3 April, 2014 by jaegarmaisteri

[DGW]

It is good to hear that your car is now fixed.

[jaegarmaisteri]

Some update. Car has been working well since. Also all the costs for repairs done, went to the car dealer and to importer. Next step now is to improve the engine, by doing some engine optimizing. They are promising up to 264hp/370N. This should spice up the car. I am bit worried about the DSG, but they should have some new program for that too. Mechanically, DSG can take this new tuning easilly.

[ConanBarbarian]

it looks like reason for my cold idle stutter was the #4 fuel nozzle. The intake manifolds were open, so it is also cleaned inside the engine.

 

What's a fuel nozzle? Are you referring to the injector itself?

Also, there's only one intake manifold on the engine so I am a little confused about it being open...

 

I'm having some problems of my own - sometimes (like 1 in 100 tries) when starting a cold engine it would rev for a split second and die (would start normally afterwards). Also, warm engine idle (just after starting) feels funny most of the time.

The dealer is clueless (guess it doesn't depend on the country) but one independent mechanic is suggesting to take apart the fuel pump sender and inspect it for dirt causing fuel starvation during start-up. I am getting to error codes though.

[jaegarmaisteri]

Yes, sorry for my poor presentation. My native language isn't English. Fuel INJECTION nozzle, what I was referring to. And again you're right, there are only one manifold, not manifoldS. Thank You, for correcting me.

Edited 28 July, 2014 by jaegarmaisteri

[ConanBarbarian]

So what was done exactly to solve your problems?

[jaegarmaisteri]

"Now after couple of days, it looks like reason for my cold idle stutter was the #4 fuel nozzle."

 

And for you, it was #4 fuel injection nozzle, which they changed.

[brad1.8T]

What's a fuel nozzle? Are you referring to the injector itself?

Also, there's only one intake manifold on the engine so I am a little confused about it being open...

 

.

He means the #4 injector & while they had the manifold off (open) to access the injectors they cleaned the inlet valves.

[ConanBarbarian]

Makes sense. Wish I had figured it out myselft :(