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Intermittant Mis-Fire (After new leads)


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The Leads on my car were replaced, as it was expected the slight occasional misfire i was getting was caused by these.

Well, it's still doing it...... but it's hard to explain. It only seems to do it for the first 5 mins of a journey, and it's bad just as the clutch is getting near it's biting point - the car feels quite lumpy (it must be if my G/F can notice it ;-) )

Any ideas what to check next?

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Where did you get the leads from? I had a similar problem when my leads were replaced (eurocarparts) As the leads arent easy to seat anyway thwe shape of these made it even harder. Ended up taking each one off while running to find the offending one and then reseated it firmly and it works fine- sounds like you have a similar problem- especially as it was fine before.

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could be your coil pack. Its quite a common fault. Sounds silly, but have the plugs been changed?, if yes then it probably is the coil pack. I had to have mine changed on my old VR6- it started missing slightly, low down the rev range. Expensive to replace- around 250 quid from VW. You should be able to get the ignition pack checked though, to make sure it is faulty before paying out all that money!!!

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i had the same problem, ruled out the possiblilty of leads after replacing them then got really pissed at the whole car, found out after that the guy that fitted the leads damaged one of them as he was fitting it (hard to fit) so had to replace a single lead, now is working fine, when it is dark, leave the car running and stare into the engine, where the plug leads are based, if you see a spark then you know the problem is with one of the leads, thats how i found the lead was damaged after replacing it.

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Yeah i'll have a look - but he's a pretty competent mechanic, i'd hope he knew what he was doing when changing the leads really?

They're not genuine VW leads either, probably from Euro car parts or such.

I didn't ask him about the Plugs but would again hope he would have checked these....... i'll ask him anyway,

Also - i guess the Coil Pack would be next in line??

I'll have a look around anyway.

Thanks for the advice again - i'll let you all know how i get on.

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He may be a competent mechanic, but did he use the proper VW spark plug removal tool?

Yeah i'll have a look - but he's a pretty competent mechanic' date=' i'd hope he knew what he was doing when changing the leads really?

They're not genuine VW leads either, probably from Euro car parts or such.

I didn't ask him about the Plugs but would again hope he would have checked these....... i'll ask him anyway,

Also - i guess the Coil Pack would be next in line??

I'll have a look around anyway.

Thanks for the advice again - i'll let you all know how i get on.[/quote']

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coil pack probs aren't as common as a lot of so called experts would have you believe IMO.

i'd say check the leads carefully, then go from there.

thing is though, you say in your first post that it only does it when cold? if it were the leads or pack i'd have expected it to do it all the time.

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If it only seems to do it for a while...... i'm sort of stuck on what it could be though?

Obviously it's something that gets better when it's warm etc, all i can think is that it's still a Leads/Plugs issue?

If the coil pack was faulty, wouldn't it do it all the time?

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If it only seems to do it for a while...... i'm sort of stuck on what it could be though?

Obviously it's something that gets better when it's warm etc' date=' all i can think is that it's still a Leads/Plugs issue?

If the coil pack was faulty, wouldn't it do it all the time?[/quote']

If there is a fault with the coil pack in my experience it would do it all the time. Problem is that at higher revs you prob wont notice as much due to the fact that the sparks are occuring so much quicker it becomes virtually un-noticeable.

Also temp will play a factor in it due to moisture in the air allowing a path to earth for the current to go through. as the engine warms up, the crack may slightly decrease in size and thus reduce the conductive path. coil packs are a common item to go on any electronic ignition system. i was just changing one the other day on a mates Renault. He had bloody two of them!!!!

[ Edited Thu Jan 06 2005, 12:54PM ]

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It's not hesitating, when it does it, it's definitely mis-firing as the car will do it when idling, feels like it could stall??

I suppose hesitation is also true though.... as when driving it like this it does hesitate, but sort of feels like a misfire.

How can i tell the difference? Surely if it does it when idling that's a mis-fire?

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