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[Nickh]

After a fifteen mile run last night, I noticed that my 2.2 GLS (52 plate) was chugging on tick over.

This morning after a 50 mile run along a horribly wet motorway, the beast is still misfiring on tick over, which is now much lower than usual. Oh, and there is a distinct smell of fuel outside the car.

The engine still revs, but the misfire is still there at almost 3000 revs . .  should I be suspecting the coil pack is in the process of shuffling off this mortal coil, or is there some other widget which might cause this problem ?  :-/

Thanks in advance to all the Omega Gurus out there.

Nick

[RobG]

First port of call is remove coilpack and check plugwells for oil.

[Nickh]

Ooops !

Forgot to mention that I did a plug (and air filter) change last month, along with a cam cover gasket change . . there was oil in the plug wells then.

Just been out and checked it . . no oil in plug wells.

Nick

[Nickh]

I've obviously confused everyone with my last post.

In spite of having done a plug and air filter change last month, the misfire only started last weekend. A friend has now established that there is a problem with the air regulator widget in the air inlet pipe, as when he directed me to unplug it, there was no change in the rough tick over.

Is it possible that the coil pack also is not working properly, or is it more likely that the EMC (Engine Management Computer)  is knackered ?

Nick

[RobG]

Ideally need to get a code reader on it Nick

[Kevin Wood]

IA friend has now established that there is a problem with the air regulator widget in the air inlet pipe, as when he directed me to unplug it, there was no change in the rough tick over.

I assume we're talking about the MAF.

In which case, if there was no change in the idle after unplugging it, that's an indication that it's NOT faulty.

If you unplug the MAF the ECU will determine the fuelling approximately from other inputs it receives hence, if the MAF was causing it to run poorly, it improves with it removed.

First thing to check is the ignition setup if there are no fault codes indicating trouble elsewhere.

[Nickh]

OK . . thanks for all that.

Yes I did mean the MAF . . I couldn't remember the name of the thingy !

Right, I managed to persuade my local friendly garage to stick his diagnostic machine on the car a couple of hours ago. It came up with four faults :
1. MAF error (it was unplugged at the time).
2. High voltage on a part of the wiring associated with the MAF . . . can't remember the specifics.
3. Misfire on No. 4 cylinder.
4. Crankshaft position sensor error.

I re-connected the MAF, and ran my poor 'miga up and down the road a few times, and he re-tested the car. This cleared all but one fault:
1. No. 4 cylinder misfire.

So, it was decided that the coil pack is on its' way out . . is that correct ?

He did say that he recommended that the coil pack is replaced, and then the car put on his machine again, just in case the crank shaft sensor error crops up again.

I would appreciate any advice on what I've done, and which if any, coil pack to get . . there's a few out there.

Thanks once again,

Nick

[Kevin Wood]

Sounds to me like it could well be the coil pack on that cylinder, assuming the spark plug is OK.

Beware of the crank sensor too. If it's starting to throw up codes (P0335 I believe) it will leave you stranded sooner or later. I'd replace that with the cable routed well away from the exhaust, per the maintenance guide.

EDIT:
Ahh! Spotted it's a 2.2. Crank sensor not normally so troublesome on those (sure it's not the cam sensor?), and, IIRC it will limp home if it fails completely. Keep an eye on it, though.

[Nickh]

Well it's not the coil pack that's knackered !  :-/  The replacement arrived today . . still chugging like a tractor.

Any ideas ?

Nick
(Really fed up . . surrounding lots of beer)

[Kevin Wood]

Well it's not the coil pack that's knackered !  :-/  The replacement arrived today . . still chugging like a tractor.

Any ideas ?

Nick
(Really fed up . . surrounding lots of beer)

The other possibility is the fuel injector or the wiring to it. They are normally reliable though.

Or perhaps that crank sensor issue is causing problems? Can't see it affecting only one cylinder though.

See if you can chase the injector feed back to the ECU pin and check for continuity? Also check resistance at the injector (10-15 ohms would be typical).

[Nickh]

Thanks for that Kev,

I think I'll check that in the morning . . so much beer to get through here . . you set targets  . .  you gotta achieve them !

Many thanks

Nick

[Nickh]

* . . . take this compression tester and check the compression", said my mate Paul, "I have a feeling it could be a head gasket".

Sure enough pot 3 was half the compression of the others . . huh . . pot 3, not 4 ? Yep, on removing the plugs to do the test, I found a chunk missing out of the ceramic on pot 4. Bingo ! There's the cause of the misfire.

So a new set of plugs, a skimmed head with a new gasket and the beast is behaving itself once again, with no faults on the test equipment. 

My thanks to all for the help and advice offered . . until the next time.

Nick

[Vamps]

* . . . take this compression tester and check the compression", said my mate Paul, "I have a feeling it could be a head gasket".

Sure enough pot 3 was half the compression of the others . . huh . . pot 3, not 4 ? Yep, on removing the plugs to do the test, I found a chunk missing out of the ceramic on pot 4. Bingo ! There's the cause of the misfire.

So a new set of plugs, a skimmed head with a new gasket and the beast is behaving itself once again, with no faults on the test equipment. 

My thanks to all for the help and advice offered . . until the next time.

Nick

When my head gasket went there was a steam trail behind the car and hydraulic lock, on trying to start the car....   They do go between 3 and 4, but keep and eye on the cam sensor.....

[VR4Dave]

Sounds like you found the headgasket failure by fluke and the plug was the culprit for your misfire. Good result all round