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[GPar]

Done a lot of work on this car in the three and a half years I have owned her. All the usual Omega V6 stuff. She's been running really well lately and then suddenly on Wednesday a misfire developed. Seems to be only firing on 5 cylinders. Now, I had the same problem just under 3 years ago and the local garage (hadn't found this forum then) fitted a new coil pack and leads which cured it. That pack and leads has done about 42k since then. Could it have gone again? I don't know if a genuine replacement was fitted. Before you ask, I did the paper clip test with engine not started and only got 12 and 31. Worryingly, since doing the test the engine management light is flashing when I start the motor but it wasn't at all before I did the test. Any thoughts would be most welcome.

Geoff
p.s. rocker gaskets and breathers done within the last 18 months (breathers again recently) so no oil in plug wells.

[rustym95]

would change the leads, there still could be oil or water in one of them plugs,

[feeutfo]

plugs? 40k life iirc

 Have plug wells been physically checked?

Flashing is strange.

[amba]

Had a very similar issue here a week or so ago,so maybe its the Medway towns  ??
I removed plug cap from passenger side bank and found them to be almost swimming in water,and when removed plugs found they had started to "rust".
The drivers side were dry ,so quick trip to FG.Barnes in Parkwood for a new set of 6 GM plugs and an hour or so later car runs like a dream again. Worth checking them first since this really heavy spell of rain.
If you want to try a replacement coil pack I have a known go one here.(oval plug type)which you are more than welcome to try and see you are local to me..drop me a pm and we can sort out.
You may find the eml is flashing as a sensor is picking up either unburnt fuel or an air leak..when mine problems started I had 89 come up on the fault codes which was oxygen sensor !!.
If you need a second opinion just let me know and I will pop round,as 2 pairs of eyes might find the problem .

[GPar]

Many thanks amba. I've actually ordered a new coil pack as I was convinced it was the same problem as before but it hasn't arrived yet. Weather permitting, I'll have a good look at plugs today. I pulled all of the drivers side leads off and they were dry but I'll check the passenger side as well. Plugs were changed when I did one of the services about 30k back. May still need your help so many thanks for offer. Hopefully EML flashing will disappear when problem solved but that's still worrying me as I've never seen that before whilst I've had the car.

Geoff

[GPar]

Found out why EML was flashing. Forgot to take out paper clip after I'd done the test! Doh! It's me age you know. Just off to get new set of plugs to try first. Got son out of bed to run me to FG Barnes! He ain't too pleased! My moneys still on the coil pack though.

Geoff

[GPar]

Replaced plugs, no water or oil in any of plug wells. Misfire still there. Waiting for new coil pack now. Could be leads I guess but they were replaced previously as I said. Not looking forward to taking out coil pack, bet it will be raining 

Geoff

[tunnie]

do you know which pot/bank is misfiring? Maybe pull out the leads on one bank, start it, see if all 3 fire, and do the same for the other side, see if you can find which pot is causing trouble. Then swap the lead over for known good one. If that resolves it you know its leads, if not, its the pack...

[GPar]

Well, the middle plug on the drivers side was darker than the others so I'm guessing it's that one. Good idea Tunnie, just that I haven't got a spare good lead. Only option now would be Halfords, can you buy one lead on it's own? This problem happened suddenly and I was thinking that if it was a lead breaking down I would have noticed a problem for a while but who knows?

Geoff   

[feeutfo]

in my experience dis pac fails in pairs of cylinders.(i've only changed one so correct me please)

The back of the dis shows 3 lumps. 1 "lump", iron coar i think its called, is responsible for firing 2 pots. If a lump fails two pots go down, 1 on each bank.
This meant that the engine was miss firing but balanced and sounded like a flat 4 cylinder engine, subaru style. As opposed to a v6.

However, when a lead goes down only one pot fails, (unless your incredibly unlucky.) This means the engine is not balanced, as you have 3pots firing on one side and 2 pots on the other. Result is the engine leaps from side to side violently as if its trying to jump out and walk. Quite a marked differance.

So, "in my experience" if the engine miss fires but is smooth with no vibration change dis pac. If its vibrating and jumping side to side, change lead(s).

Sounds like a rule, but as always with rules there is always an exception. Or my experience is not the norm...... See what others say.

[tunnie]

Well, the middle plug on the drivers side was darker than the others so I'm guessing it's that one. Good idea Tunnie, just that I haven't got a spare good lead. Only option now would be Halfords, can you buy one lead on it's own? This problem happened suddenly and I was thinking that if it was a lead breaking down I would have noticed a problem for a while but who knows?

Geoff   

Maybe borrow a lead from the working bank and swap the lead over? (keep care track of which one is which)

Maybe swap the leads, see if the misfire moves?

[tunnie]

just noticed your in Chatham, maybe drop LSG1 a PM, he may have a spare lead 

[GPar]

Thanks Chris. I seem to have a mixture of both scenarios. When the misfire started (think I should call it a nofire rather than a misfire) I was a considerable distance from home and had to complete the journey. The engine became very 'lumpy' at low revs i.e. when idling or pulling away and when driving up an incline, but smoothed out on the flat once I got the speed above about 50. A new pack should be arriving Monday so I'm going to fit that (I need to have a go at this as it's one of the few jobs I haven't done) and see what happens. It is behaving just as it did when the pack went before. I'll report back.

Geoff

[amba]

Geoff.
I am around Monday if you want another pair of eyes on it.
Totally agree with Chris,s diagnosis though as I eneded up replacing dispack which had no eveidence of burning or damage.
If plugs are now good and new ,worth the Tunnie approach of swapping over the leads 1 at a time and seeing if the problem is them cured.
Best of luck and please report back

[GPar]

Thanks again for the offer amba. Hoping that new dis pack will arrive today but I can't see me doing it in this weather. What I thought I would do is unplug the leads leaving old pack in situ, connect to new pack without bolting pack in place and check whether that has solved the problem.

Geoff