Omega 2.5 V6 misfire

[dan-eboy]

Hi everyone, I have an Omega 2.5 V6 manual, and have been struggling for a couple of months with a misfire. To cut a very long story short i have replaced, Spark plugs, HT leads and coil pack and it's still the same. I have checked for fault codes and there is just 21, for throttle position sensor. It seems to be mis-firing on 3 and 6.

Now the only thing left i think it could possibly be is ECU or broken/dodgy wire from ECU. I have a very small amount of electrical knowledge and a multimeter, but i looked and the wiring diagram in the Haynes manual and it's melting my brain a little bit! I know there are 4 wires going to the coil and 1 is live, I guess the other 3 are pulses which tell each set of 2 leads/plugs when to spark. I have found 3 of the wires (1 live and 2 others) but cand find the grey/black trace. The live seems to be fine but does anyone know what sort of voltage should be going through the others and if it is a pulse?
Or If it might even be something else i am missing?
Any help will be much appreciated i am running out of ideas now!
I can post pic of wiring diagram if that would help, Thanks, Dan

[Paul]

The coil pack you replaced, is it new?

[dan-eboy]

Yes brand new and genuine, I put an ebay cheapy on 1st time and seemed ok then couple of weeks later it was back, I put it down to cheap coil pack and bought new, genuine but no difference.

[Paul]

Could do with trying yours on another car to be 100% its ok

You don't say where you are in the world.

[dan-eboy]

Oh i'm in Horsham, West sussex, ill update my profile. I didn't think it was as easy as just plugging it in, thought you had to change immobiliser ecu and key chip or something, thats what i was told anyway?
Did you mean trying the ECU or coil pack? i thought you meant ECU?

[dan-eboy]

Any more ideas anyone?

[roadkill]

One or two things you can check on here> Vauxhall

[dan-eboy]

Thanks some good info on there , but how would you check pin 1 (or any pin) on the ECU if the loom is plugged in? If thats a common problem it could be mine! I know that pin 1 goes to the dis-pack!

[roadkill]

Thats on Vectra B 1.6/1.8 16V 96-98 v6 stuff is lower down list

[dan-eboy]

Well, i've put a new ECU in and hey presto - all cylinders firing! So pleased that was my last option before the bin! Thanks all for your advice , much appreciated!