Misfire - is it the coilpack?

[osevr6 0]

Ok, so I have a misfire. Nothing much at first, but getting worse.

It happens mostly at low revs/high gear and when the engine is warmed up.

I've changed the leads (twice) and the plugs (no.6 was fouled).

Vag-com shows no errors.

I tried the water spray on the coilpack at night, couldn't see any arcing, but misfire was terrible and the coilpack has a crack along the front edge.

So, do I take the plunge and get another coilpack?

Or is the no.6 fouled plug a sign of something more sinister?

If it is coilpack problems, does anyone recommend Probe? £95 + postage on ebay seems good to me.

[Petesvw 0]

I'd be tempted to test your fuel pump relay mate! Mine went gradually getting worse and worse!

Open it up and clean the contacts, it should work as a temporary fix (if it is that).

Its No:167, bottom right in the fuse box.

I put a coilpack on only to find it was a £20 relay!! : (

[sooty 0]

hi mate i had a bad misfire on mine and also changed the plugs leads coilpack ect..... and it turned out to be the hall sensor (camshaft sensor) they are expensive but a quick clean might do the trick it is located behind your coilpack

[daniles 0]

there's two parts to the cam shaft sensor intenal and external, i had to change the internal part which is basically a magnet.

[crish72 0]

You certain it's not the plugs or leads?

I've just changed mine, 1st set of leads arked on 2&3, swapped them again and still arking.So now ive got a bit of insullation tape wrapped around the end of the leads and it stopped the misfire.

Not the best method i know,but it worked.

Chris

[osevr6 0]

Thanks for all the comments so far.

Took the fuel pump relay apart yesterday and cleaned the contacts as suggested.

Today the car is a bit better, only misfires at maybe less than 2000rpm when in 4/5th. Sort of a stutter and then clears and pulls cleanly.

I remember the fuel pump was getting noisy, and now it's quitened down. Maybe it's pulling a lot of current, 'cos it's on it's way out. Would explain the improvement with the cleaned relay, perhaps?

As for the hall sensor, wouldn't vag-com have shown a fault?

[jpc 0]

mine was missing between 1000-2000 rpm, I changed the coil pack 1st after I seen a little crack on it and it turned out to be tottaly cracked on the underside!

Might be worth taking it of and looking?

Anyways this made it a bit betterm I then changed the plugs and that fixed it, so for me it was a combo of the two.

[Eat this 2]

take the coil pack out and put silicone sealent on it this will stop it arcing as long as you let it dry/set properly (overnight should do it)

[osevr6 0]

So it continues...

Fitted a new coilpack, ticks over much more smoothly now.

However, misfire under load is still there!!!

I have also tried a new fuel pump relay, had to wait for the old one to cool before I could remove it - it was hot, hot, hot (Is that normal?)

Strange thing is that it wouldn't run with the new relay. I've exchanged it, but not tried it yet, I'll keep you all posted.

Thanks again for all of the ideas etc.

[osevr6 0]

Finally, I tried the new new fuel pump relay. Looks like the misfire has gone. I suspect the fuel pump is on it's way out - looks like that's going to be the next job!

[adam_christie 0]

Hmm, this may be the problem I'm suffering from too then.....(see "Buzzing - Fuel Pump Methinks!" thread) I'll swap the relay and see if it helps. My car's taking forever to start when hot too, any clues?

[osevr6 0]

Update Update

I put up with it over the winter, but took the plunge and bought a new fuel pump (£75).

Fitted it last weekend, and YES! Misfire is gone!!!

Pulls cleanly from 1000-2000 rpm in 5th, just like I remember!

Engine also runs cooler (?)

So, a few pointers -

If the fuel pump relay is really hot, the pump is shot. With the new pump (not a genuine one), relay is cold.

The old fuel gauge sender was an unrecognised part number (1HO 919 673G) - add £40 for a new sender (1HO 919 673F) to fit to new pump.

The aftermarket pump is a poor fit - I reckon it may come loose.

Get used to the smell of petrol while you do the job!

OseVR6