Misfire when cold VR6 - HELP PLEASE!!

[oxfordpaul 0]

Hi all,

 

My car has developed a really bad misfire when cold which virtually disappears when warm. It starts fine, idles fine but will die if you prod the throttle. It'll rev if gentle throttle is applied and is ok past 2000 rpm. I have to slip the clutch to get it to go when cold.

 

The garage have replaced the blue temp sensor, leads, plugs and coilpack to no avail. The ECU has been swapped with another car, again no change. Having read up on here I'm thinking MAF meter - could these symptoms be caused by a faulty MAF or would that not make sense given that it gets better when warm? What about the Lambda sensor? I noticed it revved fine from cold whilst on the 'choke' i.e. for the first few seconds and then went bad. I'd say it was throwing too much fuel in as it smelt rich when this was happening....

[oxfordpaul 0]

Anyone any ideas?

[Crasher 3]

I have had a number of late VR6 Corrado's do this (the AMM changed in 94) due to AMM failure that gives no fault codes. Also, failure of the ECU relay causes this.

[Heardy 0]

Anyone any ideas?

What grade of oil are you using?

[Crasher 3]

What grade of oil are you using?

 

I can see your angle but it doesn’t sound like lifter pump up to me.

[oxfordpaul 0]

I've just had the oil changed to Quantum Synta Silver 10w/40 I think? What effect would the oil have?

[Heardy 0]

What grade of oil are you using?

 

I can see your angle but it doesn’t sound like lifter pump up to me.

I was just wonder because mine developed a really bad missfire,it turns it was due to it having Mobil 1 in it all it's life.

It ended up knackering the oil pump up and causing to much oil pressure keeping the lifters open and giving it a really bad missfire.

[craigowl 0]

Heardy wrote:

I was just wonder because mine developed a really bad missfire,it turns it was due to it having Mobil 1 in it all it's life.

It ended up knackering the oil pump up and causing to much oil pressure keeping the lifters open and giving it a really bad missfire.

 

Intersting post which may set the cat among the pigeons!

[Supercharged 2]

Heardy, did you get anything out of Mobil - I've heard several stories now of Mobil 1 killing VW oil pumps, especially in Corrado's!

[jimmy83 0]

sounds like the same problem I have with my 2.0 16v, almost exactly in fact....starts fine, then runs three a few seconds later. If I flick the MFA to oil temp, as soon as it hits 80, the engine starts firing on all four cylinders again...Plus I also get the fuel smell, although this is simply the unburnt fuel from the misfiring cylinder. Makes me think that mine could be ecu related too, rather than with the fueling etc. will try the relay tonight. Let me know if you have any luck with yours!

[Heardy 0]

Heardy, did you get anything out of Mobil - I've heard several stories now of Mobil 1 killing VW oil pumps, especially in Corrado's!

No i never even thought about it.

I just put a new pump on and it sorted it.

It was RW1 on here who put me on the right track :notworthy: .

[oxfordpaul 0]

Great news, it was the MAF and I got a second hand one for £60 although Storm VR6 bought the one from GSF for £65 exchange and that works too (even though GSF etc swear blind it won't work - the only difference being the 'A' on the end of the part number...