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[vic]

Investigating an intermitent misfire at the moment whilst working my way thru some issues. Is there a way of testing the dispack on a (2000) facelift 2.2 .4 potter, perhaps with a multimeter? There are lots of threads saying " replaced the dispack but misfire still there". At circa £70 a 'pop, I'd rather do some diagnosis first.
Thanks guys.
VC

[Boatboy]

I asked the same question about 3 months ago concerning a 6 cyl, but did not get any replies.

For info I was getting 10.3kohm across each of the  3 coils (the v6 sparks in pairs, one used one wasted) but I was definitely misfiring on 2 cylinders ie one pair, and the problem was solved by biting the bullet and fitting a new dispack.

Not sure how useful a basic static resistance measurement is compared to the real world scenario of forcing electric to jump a gap in a pressurized cylinder. Maybe someone will know and happen along shortly.

Steve

[bluepoint]

Investigating an intermitent misfire at the moment whilst working my way thru some issues. Is there a way of testing the dispack on a (2000) facelift 2.2 .4 potter, perhaps with a multimeter? There are lots of threads saying " replaced the dispack but misfire still there". At circa £70 a 'pop, I'd rather do some diagnosis first.
Thanks guys.
VC

Could be the dis pack but any decent mech will say when replacing it, it is wise to replace the plugs and leads aswell all in one job that way you have eliminated most of the electrical faults that may cause the fault that you describe.

[Sixstring]

The only sure and definate electrical way I have found to test a dispack is to use a "clare" tester and do an insulation resistance test. You CAN use a megger or similar, but it is only a basic "it might be" test.

Haven't ever been able to DEFINATELY say, yes, its ok, or no, its buggered until I put it on the clare.
better to bite the bullet. IMHO.

[CaptainZok]

Use a test plug and fire it with Tech 2 is the official way.

[vic]

Thanks guys keep the info' coming please, it really is much appreciated. Went to my local 'stealers' this afternoon and have to revise my estimate upwards as to the cost of a new GM dispack, now quoted to be circa £109 a 'pop. Hence my reluctance to throw money at it without some definitive info.
Seriously considering an LPG conversion but have to get these basic issues sorted first
VC:-/.

[vic]

Just took off the dispack and noticed what appears to be mayo' on the rubber boots that live in the  two plug wells nearest the skuttle. I'm struggleng to understand how water would get into the plug wells via the water jacket at the head/block join, but I've never had a head off this design so am happy to accept guidance. What do you think could this be a head gasket gone? or do I gave a rainwater leak?
VC :question

[Entwood]

There is a "join" in the scuttle that is prone to leak, it is supposed to clip together but sometimes water gets through and drips onto the DIS or the #6 area ... Some folks put a bead of silicone sealant on the join to prevent the leak ...

The scuttle "clips" to a "bar" under the rubber seal at the base of the windscreen .. if the rubber is damaged and the clips are missing it might also leak down there ??

Might be worth a litre or 2 of water on the windscreen above the join to see if yours leaks ??

[Marks DTM Calib]

Right....lets get into the principles of operation.

The coil works by energising a primary winding, this in turn effectively 'stores' energy within the magnetic core of the transformer.

When the current to the primary is removed, this stored energy induces a voltage in the secondary which fires the high voltage through the plugs.

So, you can do a basic test using a meter, you should get a few ohms on the primary windings and 6-10K ohms on the secondary.

You could also do an insulation test.

But, the reality is this is not telling you much as the common failure is a rusted core and this will not effect static readings. When the core fails the energy that cna be considered stored is much reduced.....and hence the secondary voltgae for the spark drops off dramaticaly.

So, the only fool proof method is to use a test plug which will have a gap of 30-40mm and observe the spark.

[vic]

Having removed the dispack and as Entwood suggested checked the skuttle. The sponge underneath, and above the spark plug cover appears very damp, with a squeeze it produces evidence of water droplets on the fingers. I hope I'm on the right track. I took the skuttle off recently to deal with a wayward power sounder and to clear the drain, so tomorrow I will revisit the windscreen seal to see if its just water ingress. Have done the multimeter ohms checks on the dispack and all seems to be consitant at 8.22 Megga ohms per plug outlet. Oh' how I hope I've found the cause of my misfire and its not a HG. I can do the work but would rather not have to go thru it all. Her indoors is loaning me her Vectra at the moment and may have something to say if it goes on too long. Will keep you posted. Thanks for the help guys!
VC

[vic]

RESULT!
Checked the windscreen seal and placed a silicone bead along the rubber I had disturbed (thanks Entwood for the pointer). Also had some excellent advice from kevin Wood which confirmed all electrics functioning as they should now (thanks mate, if you need more time on the 'sticks' to improve your landings just let me know )
Two weeks on and all is running as it should and the car is a pleasure to drive again.
The cause; Water ingress thru the windscreen seal into the plug wells after removing the skuttle to deal with a wayward power sounder and blocked drain. Once the water was cleared away from the plug wells nearest the skuttle and the silicone done, its like a new car to drive. So glad I didn't just throw money at a new dispack without getting good advice first. Once again my thanks to all those who shared their thoughts and experiences..............Wahoo' I'm on the road again and enjoying instead of dreading my omega
VC