05 GTi stuttering, again.

[supersport]

First of all I am a new user so hi.

I have had my car for about a year now and when it is working I absolutely love it, but have been having some grief for a while now.  It has just ticked over 90K miles.

It first stuttered on me about 8 months ago, but only did it once and never again.  Fine all summer long and a complete blast.  Come the Autumn and it started doing it again, seemed to be coil packs which had been replaced FOC by VW, so I took it back.  They reported all fine, but the divertor valvle was caput so had that replaced, ouch they know how to charge!

All was fine for about three weeks, and then one day it just was appalling and undrivable, constantly missing above 40mph and once warm at any speed.  It was lick a switch was flicked as soon as it got up to temperature it start missing.  So took it to a local chap who is pretty smart.  He reckoned it was either the injectors or valves so applied some cleaner and all was fine again for two weeks.

This was just before Christmas and we were going away, so he gave it a treatment of valve cleaner and then it was fine for about 1000 miles before throwing up the odd stutter under hard acceleration.  We have reapplied the treatment three times now, and the gap between treatment seems to be dependant on the kind of driving we do.

Over Christmas we were up and down the motorways and with trips to Autosport it did lots of high speed long distance driving.  Since the last treatment, it has really only been used around town, and now with 300 miles it is stuttering again.

So finally to my question; it seems that maybe the valves are well coked up and town driving really cacks them up and we get sticking, does this sound reasonable.  And if this is the case, is it possible to clean them up without stripping the head down, is there anything else that cause this?

If it is likely to be the valves, any estimates on likely cost?

Apologies for the long first post, but hopefully I can get the car back to its best before the wife gives up on it.

Thanks

[bacillus]

When did you last change your spark plugs?

[jimk04]

Check the pcv aswell, may be the reason for fowling up.

[supersport]

Spark plugs were done 10,000 ago in the major service.  In the original diagnosis the plugs/coil packs were moved around and yet it still missed on the same cylinders.

I did the PCV test yesterday, and on pulling the dip stick the car got quite rough, so I assume this is ok.

[lee_]

Fuel based valve cleaners will have little effect due to the TFSI being direct injection (fuel doesn't flow over the intake valves). Apparently you can remove a sensor on the inlet manifold and allow cleaner to flow in there slowly through a football pump needle. A quick search should reveal more about this.

I'd be tempted to try before head off work. 

[brookesb32]

I Would get it on someone's VCDS and see what pops up. I had stuttering on mine which was fixed (so far so good -been a good few months) by having the tumble flap reset, it gets stuck.

Not saying that is your problem but worth a look into. My thread is on here somewhere about stuttering/hesitation. If you do an advanced search of my threads you will find it may help 

[jamma]

When did you last change your spark plugs?

.

I agree , I had this . 36 quid for some new ngk's and sorted . I had the Bosch ones fitted 4 weeks before and it never helped so binned them and fitted NGK , never stuttered again and that was 12000 miles ago .