V6 Misfire

[Denis]

I'm beginning to think my V6 has some kind of misfire. Very occasionally it does a kangaroo type jumping thing when I accelerate from say 20 to 30. But it seems all the time there is a kind of hesitance, hard to describe- very slight, as if I am always driving over a slightly bumpy road.

 

I thought that the ECU would warn me if there was a problem, via the engine warning light on the dash- I know it is capable of detecting a faulty coil pack perhaps because of the unburnt petrol in the exhaust?

[Guest nimrod]

True the engine check light should warn you of any problem but only if the missfire is bad enough to upset the mixture so bad that it effects the reading from the lambda sensor, well thats how I understand it, if its just a slight missfire and not affecting the gas levels passing over the sensor then the light will stay off

the coilpacks are a known issue and with the age of you vehicle it should be a warrenty job if one has failed

[Dally]

Denis

 

My V6 auto is the same. Been back to dealers twice for this - They can find nothing wrong (no codes).

 

Learning to live with it even though I know it's not quiet right (at times it's really ultra smooth).

 

I did contemplate taking it to a vw specialist in Nottingham called C & R enterprises - they are acknowledged as experts in the field, but just haven't got round to it yet.

[Guest nimrod]

Dally depending on where your located/ you could try

 

http://www.auto-amd.com/home.asp

http://www.apreurope.com/index.html

[Denis]

I have browsed other VW orientated sites and it seems the ECU fault logging is pretty sensitive and precise, so it's odd that Dally's doesn't show any codes. Mine is booked in on Wednesday, will post if anything shows up.

 

Of course it could be the gearbox I suppose?

[Guest vinny2984]

Dont want to upset you but I've been trying to fix the same fault for nearly a year.

" trips to ford and 3 to vw and 1 to an independant.

Toptip

Dont go to ford, their diagnostics cant pickup the fault.

VW can, I've just got back from an independant today who said exactly the same, when they tried to view the faults as a ford, nothing came up, so they tried as a VW and hey presto 5 faults.

 

problem is they cant work out whats causing the faults.

The usual have been done, ie ht leads, plugs, and the not so usual cat, maf, speed sensor, alternator

 

The garage today is very doubtful its the coil but says its an outside chance.

They basically said to me they would have to replace and try a few things but each one would need paying for.

 

Unless someone on here has any bright ideas, I'm gonna sell it or burn it.

[Denis]

Any idea what the fault's were Vinny?, ie "misfire on cyl 1", etc?

[Dally]

Thanks for the links nimrod but I'm actually in the East Midlands so C & R are not too far away. I'm just struggling with whether I want another headache of chasing and pursuing this at the current time ( got a lot on at work and home) but may do so in the near future.

BTW Denis and Vinny 2984, I have a slight unusual roughness / vibration in the engine when it revs between 1000 - 1100 either on acceleration or deceleration about 80% of the time. I've noted that when this doesn't happen (ie the other 20% of the time), the engine runs really smooth and there are no hiccups whatsover.

 

Any experience of this??

[Guest nimrod]

Another one for you would be http://www.awesome-gti.co.uk/ they get a good mention in the VW mags

[Guest vinny2984]

it came up with faults on maf, lamda and 3 others i dont remember, mechanic says something is throwing them out, the maf and lambda aren't actually faulty.

 

Dally, yours sounds alot like mine.

mine misses upto 1500 rpm, worse under load, quick pull away or accelerating on hills. But it has good days and bad days, or even worse good miles and bad miles. There's no reason to why or when, but its getting worse and more freequent.

If i put it in drive with handbrake on, its realy rough.

 

Someone suggested coil pack and if so it would be worse on wet or damp days, but weather makes no difference.

 

i got the problems but unfortunately no solutions

[Dally]

Yeah, mine does feel rougher when you are stationery with brakes applied but in drive.

 

Strange thing is that I test drove about 3 V6's before I bought mine and they all showed this characteristic roughness between 1000 and 1100 revs. I know this can't be just a characteristic of the VR6 because of the good days (or miles) as you quote.

[MrT]

I have always thought that the V6s had a lumpy idle as felt through the drivers seat but fine when driving. This has happened on both the Mk1 & Mk2. Yesterday whilst working on the car, I turned the Air-Con off and you could hardly tell that the engine was running, smooth as silk.

[Richmond]

In case it helps:

 

A coil went on mine earlier this year (apparently there is a coil for each cylinder, which seems a bit over the top - I'm surprised that all 6 ever work at the same time). It was obvious that the car was missing on one cylinder, but it drove OK. I did about 700 miles on French m'ways at about 85 mph, bit more gear changing than usual and the engine light flashing at me the whole time (the flashing light means a problem, get it looked at, the constant light means stop driving unless you want to replace the cat). Fuel consuption was even higher than usual; presumably a sixth of it was going straight through the engine. The loss of power was only really noticeable on steep hills (the car was fairly well loaded).

[Denis]

Dally et al, I have done a few experiments and I would say my car isn't happy between about 1000 and 2500 revs. If I hold the revs at that level it seems sort of hesitant/ uncertain- but not as bad as the kangaroo jumping it does now and then.

 

It was in the local dealer yeaterday, surprise surprise they found nothing logged on the ECU.

[Guest SA Intruder]

204bhp VR6s have very poor quality coils - one per pot. Subject to an ongoing recall. Affects 2002-2003 vehicles it seems (VAG will tell you).

 

VAG change the lot, Ford try and find the duffer and replace it singly. Since their diagnostic skills are less than zero, you're buggered long term, because sure as eggs the rest will go in time.

[Guest nimrod]

204bhp VR6s have very poor quality coils - one per pot. Subject to an ongoing recall. Affects 2002-2003 vehicles it seems (VAG will tell you).

 

VAG change the lot, Ford try and find the duffer and replace it singly. Since their diagnostic skills are less than zero, you're buggered long term, because sure as eggs the rest will go in time.

VAG were at the start of the coil pack issue only changing the duff ones! this practise was due to the shortage of coil packs at the time I believe! they have now a greater stock of them and have improved the manufacturing quality of the coil packs

IIRC on VW coil packs there is a way to tell if yours are of the duff variety! IIRC it was something to do with the colour of the paint used to mark or seal them or the serial/batch number?

I will try and dig out the info from the VW NG's if I can find it on Google, if its still there that is?

 

a VW coil packs off a VR6 top one 24V lower one 12V

http://speedwagen.vwmafia.net/cars/coils.jpg

[Guest Davtona]

Guys I know I'm a Newbie but I had the same (sounding) problem on my 97 V6, the fix was new plugs and leads, - there was an intermittent short from one of the leads on the coil pack. I fixed it originally by just cleaning all the crud off the coil assy and leads, but decided to change plugs and leads as a precaution. The F.Inj system also benefits from a dose of injector cleaner, mine runs a lot cleaner at low rpm with very small throttle openings (better atomisation) when treated to some "Nitrox" - but don't overdue it or the cat will suffer. Hope this helps.