Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: SteveS on 11 November 2009, 00:00:15
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Here's the problem. It started with a mis-fire which only lasted briefly at low revs and happened a couple of times on Saturday. Then on Sunday the misfire came in continuous at all running conditions and hasn’t gone away since.
The plugs are fairly new, I changed them a couple of months ago when I replaced the gaskets on the Cam shaft covers, and I remember thinking I hope I don't have to change the HT leads or DIS pack as the access is very tight to say the least.
I've just been doing a few checks and it appears the mis-fire is on cylinder 3 and although I could detect a spark from the HT lead it was extremely weak in comparison to the other cylinders. The spark is just visible and jumps across no more than a 1mm gap whereas the others it jumps at least 6mm.
The conclusion I have drawn is that it is either the HT lead or the DIS pack. Is there anything else I can check to confirm either one without having to take them off the car? The last thing I want to do is change the DIS pack only to find it’s the HT lead or vice versa.
I did a check on the ECU fault codes and found only 12 and 31 which is normal with the engine stopped.
Any advice would be appreciated. Also thanks for the welcome many of you have given and in particular the offer of assistance from Welung666. If I still have a problem next week I may take you up on it.
Steve
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Have a similar situation here,Steve.
I had a second hand dispack fitted last year when car was playing up with erratic misfire.
Problem started again last weekend and like you the plugs and leads were all renwed last year ,about 30k ago.
I did a paperclip check and got code 89 which advised low voltage at oxygen sensor,but when posted conclusions to forum,general advise was dispack.This I removed on Monday,which in fairness was not too bad a job,just very tight and mostly done by feel.I found it so much easier to get the old unit out with the HBV removed which will also give me a chance to give the heater matrix a good flush through so several jobs can be done at the same time.
When the old dispack was removed it had no evidence of deterioration or splitting of the casing,just a small amount of heat marks across the base,so my fingers are very tightly crossed that when I refit the brand new genuine bosch unit today ,the fault is cured.
These cars do seem to work a bit on a process of elimination ,but if you are getting a weak spark,my money is on dispack......bought mine from Vauxhall warehouse in Romford, Essex and they got the new unit here the next day for a postage cost of £6=50.
Warning though.....with your car year it could be either an oval/or/rectangular plug connection so need to have a look first..........mine was oval and similar year and model.
Best of luck ,and I will report back later today when mine is back on and hopefully running fine again.
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Thanks Amba06128 sounds a similar problem, however I didn't change the HT leads when I did the plugs as they seemed to be in good condition at the time and were working fine. They are 10 years old so may be on the way out.
What is the HBV?
I know the DIS pack has an oval plug and I even got the part number off it, but getting it out loks difficult.
Steve
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Hi
HBV = Heater Bypass Valve. 3 water pipes and one vacuum pipe connected to it.
Alan
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Thanks Alan. I had noticed coolant pipes going into a valve, also breather pipes electrical wiring and plugs all in the way. So I suppose I'll have to drain down the coolant system as well.
Steve
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My 2.5 petrol Elite had the same type of problem some time ago, first changed plugs, still had problem, replaced HT leads, things were better, but the best thing was to replace the plugs again with NGK Iridium IX's. That was at 117k, not a problem since with over 165k (2 1/2 years later) on the clock.
regards
richard a
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Just for the record I tried replacing the HT leads first but it made no difference. Replaced the DIS pack on Saturday and the problem is fixed. The thread on changing the DIS pack showed some pictures of a severely corroded Dis pack and mine was just the same and I'm surprised it even ran on 5 cylinders.
I have replaced it with a non-Bosch part so I guess only time will tell whether its reliable. I was finding it difficult to get a Bosch one to match the existing part number at reasonable price and delivery . For price and delivery speed I can recommend aapoldham through Ebay.
Steve