Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: woolley11 on 13 June 2024, 06:37:11

Title: Intermittent missing
Post by: woolley11 on 13 June 2024, 06:37:11
Morning all

Know it’s been mentioned heaps of times before with other members cars, but this 3.0 MV6 of mine started missing the other day - in fairness it has been laid up a while.

There is reasonably fresh fuel in it so don’t think it’s old fuel as I put a chunk in when I taxed it at start of month.

This is only seemingly at low revs as cruises ok at 70 and the problem is intermittent. Thought I’d given it a good blow out yesterday as travelled 15 or so miles at 60-70 without so much as a peep, but on way back there was the odd tell tale hiccup.

So I guess it’s either plugs, leads, coil pack or combo.

To save the pain in arse coil pack replacement, could it be more down to lead(s) breaking down ?🤔🤞

Just with it being intermittent I’m thinking coil pack unfortunately.

I’ve a spare set of leads so it’s probably process of elimination - fitting them is not too easy with the delightful location of said coil pack.
Title: Re: Intermittent missing
Post by: amba on 13 June 2024, 09:08:43
Pull a plug lead from each side and check if any oil or water around plug...if so suspect cam seals are leaking which in turn causes many other possibilities as below.

Leads break down over time ,so do plugs and coil packs so all usual suspects but start with the above first
Title: Re: Intermittent missing
Post by: TheBoy on 14 June 2024, 11:43:27
This sort of issue, but with no codes stored, is more often HT related as you suspect.  Difficult to guess which part -plugs, leads, DIS - without visual inspection.

Defo check plug wells as per Amba's suggestion as part of this.
Title: Re: Intermittent missing
Post by: woolley11 on 20 June 2024, 16:36:02
Well I’ve had chance to pull 5 of the leads off.

The 6th been the one on the N/S at back of engine without some dismantling- which I was looking to avoid.

All 5 examined were dry of oil although possibly some moisture on N/S bank. Probably with it being laid up in the weather we’ve had.

I’ve dosed the insides of leads removed  with WD40 and given the area around the rear of the N/S a liberal spray of WD40 to deter future moisture.

Took for a drive and all seems fine at moment 🤞
Title: Re: Intermittent missing
Post by: Doctor Gollum on 20 June 2024, 19:18:53
Well I’ve had chance to pull 5 of the leads off.

The 6th been the one on the N/S at back of engine without some dismantling- which I was looking to avoid.

All 5 examined were dry of oil although possibly some moisture on N/S bank. Probably with it being laid up in the weather we’ve had.

I’ve dosed the insides of leads removed  with WD40 and given the area around the rear of the N/S a liberal spray of WD40 to deter future moisture.

Took for a drive and all seems fine at moment 🤞
And people wonder why they have misfire issues. :-X

Title: Re: Intermittent missing
Post by: cam.in.head on 21 June 2024, 18:28:44
sounds like a damp issue and the warmer weather and wd has now has sorted it . obviously the main culprit usually is water down the plug wells possibly dripping from the scuttle especially rears.
BUT it could obviously be the coil or a lead breaking down.  anytime you have the leads off they can be measured for continuity with a meter. expect a reading in the k ohms range and higher on the longer leads rather than equality.
Title: Re: Intermittent missing
Post by: woolley11 on 24 June 2024, 20:54:17
Fingers crossed it’s ok now.

I’ll be keeping watch on it
Title: Re: Intermittent missing
Post by: Keith ABS on 23 July 2024, 16:42:40
 I wonder if this is the same car, Woolley, that an ABS member has posted up about very recently

2.5 V6, I advised coil pack and he also said plugs were probably 20 years old

I dont know if any here on OOF have used Iridium, but after my experiace of before and after in an LC, I advised get a set of those

At the very least, told him to use Bosch or NGK

Title: Re: Intermittent missing
Post by: Doctor Gollum on 23 July 2024, 17:40:56
I always used GM but then they used to be a sensible price.
Title: Re: Intermittent missing
Post by: Raeturbo on 23 July 2024, 20:22:05
Ngk R standard for me,  expensive plugs are only worth the extra if they are very hard to change in very inaccessible places.  Standard plugs perform better, something to do with the easier release of ions💁🏿‍♂️
Title: Re: Intermittent missing
Post by: Nick W on 24 July 2024, 11:25:41
Well I’ve had chance to pull 5 of the leads off.

The 6th been the one on the N/S at back of engine without some dismantling- which I was looking to avoid.

All 5 examined were dry of oil although possibly some moisture on N/S bank. Probably with it being laid up in the weather we’ve had.

And people wonder why they have misfire issues. :-X


When I got around to changing the plugs on mine, I found 3 reasonable NGKs in the driver's side, 2 tired NGKs in the passenger front, and an utterly oppsed GM in the passenger rear. The paperwork with the car suggested that a previous owner had been paying for six new plugs every other service. That was at the same garage who manged to fit a timing belt with all four cams a tooth out - perhaps their Tippex needed thinning :)