Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: perfferle on 28 February 2008, 22:37:52

Title: Misfiring V6 2.5 during acceleration only.
Post by: perfferle on 28 February 2008, 22:37:52
Hi Guys,

Anyone know what would cause the engine to misfire during acceleratiion only? The idle is smooth and it runs at motorway+ speeds smooth - Just the acceleration sputters though :(...

P.
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: MutantCav on 28 February 2008, 22:39:55
Crankshaft Sensor?? Dispack?? Air Leak??
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: perfferle on 28 February 2008, 22:58:20
Possible air leak!

Replaced aux drive belt last saturday. And I did remove throttle valve to 'clean' so mabey leaking on o'rings(?). Will remove again this coming weekend anyway to change s/plugs :y.

Thanks,
P.
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: albitz on 28 February 2008, 23:04:09
when changing plugs look for oil in plug wells,if present that will take you down the route of blocked breathers,leaking cam cover gaskets,which cause damage to plugs/plug leads/dis pack. :y
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: Tab on 28 February 2008, 23:50:12
doesn't missing under load point more to dis pack?
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: Debs. on 29 February 2008, 00:00:18
Quote
doesn't missing under load point more to dis pack?

Missfire under acceleration/load, but with good idle were the same symptoms I experienced when my DIS pack blew open (amazingly the car kept going though)...so DIS pack gets my vote!  ;)
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: MutantCav on 29 February 2008, 07:43:32
Well crankshaft sensor was more of an afterthought on the list...tbh thats more likely to limit revs if its failing/failed.

Dispack is most likely, air leak is possible but tbh I would have thought it would affect the full range, not just under load?? I'm pretty sure my car has an air leak (EGR or O rings) and it generally runs rough as well as hesitating sometimes under load...dispack isnt too bad to replace though, especially if you have the plenum off anyway...
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: Mike Collins on 29 February 2008, 07:44:13
Changing the HT leads cured mine of that.

Look for oil and heat damage at the plug end.
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: MutantCav on 29 February 2008, 07:46:59
I have a decent set of v6 HT leads here if you need them...fair point I guess, if its the HT leads and hasnt damaged your dispack then great :) If its damaged it though then you will need both :(
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: perfferle on 29 February 2008, 07:52:02
Hi Chris,

Will tackle plugs as planned tomorrow. If fault not corrected then :( - Please let me know what cost for leads and dispack.

Thanks,
P.
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: kevinv6 on 29 February 2008, 07:58:11
i just changed my dis pack due to misfire when i got the old one out it had split all round. i paid £70 for a new one from centrals auto supplys
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: MutantCav on 29 February 2008, 08:00:48
Hi Perfferle, I dont have a dispack for a 99 Omega I'm afraid...but I have the leads...do you still want the foglight mate?
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: PaulW on 29 February 2008, 09:59:15
Same symptoms for me, but I've had all the plugs done, and new leads on bank 2,4,6...

Still missing under acceleration though upto 4000rpm-ish tho, and hunts a bit randomly on very cold/damp starts, so my next step is getting a new coilpack on it to see if that sorts it out.

Although the HBV did give up last September, and its since then its all started to go wrong  ;D

Don't really fancy raiding a scrappy for one as you can't trust how well it will last (if it works)
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: Debs. on 29 February 2008, 12:32:02
Quote
.....Although the HBV did give up last September, and its since then its all started to go wrong.....

I wonder did the water-spray/mist leaking from your HBV also kill the DIS pack; I`m sure I`ve read recent forum posts on just that topic.  ;)
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: Calum on 29 February 2008, 13:16:05
I had the same problem a few years back and it was the dispack that needed changing.

The garage were shocking. I eventually found the answer through the ABS forum and called the garage to let them know  ::)
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: vauxsull on 29 February 2008, 15:20:56
same problem here too but only apeared AFTER  i had plugs and leads changed.... doubt very much if any "O" rings where changed on re-assemble from garage!
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: JasonH on 29 February 2008, 17:45:42
A misfire under load is often a weak spark.

I'd say HT leads are the favourite followed by DIS pack.
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: vauxsull on 29 February 2008, 17:50:43
even if it happens only now and then? travelled 60 miles without a hitch then it started again for a few hundred yards then ok again???
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: perfferle on 29 February 2008, 18:34:36
Good point!
I replaced my HPV just a couple months ago and the leak at that time could have done some damage.

Then again, the leaking rocker covers could also have done in the plug leads.

Tomorrow is plenum off day to replace plugs as planned.
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: MutantCav on 29 February 2008, 19:06:53
Damaged leads could then damage the dis pack, but may as well start with cheapest 1st...have the cover gaskets been changed now?
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: vauxsull on 29 February 2008, 19:57:56
yes the 2 covers with gaskets where changed at the same time as plugs and leads.
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: Gaffers on 29 February 2008, 22:08:46
what about the fuel filter?
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: vauxsull on 01 March 2008, 09:53:23
fuel filter changed at same time too
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: perfferle on 02 March 2008, 19:51:50
Hi Guys,
Just to let you all know the result of Saturdat's attempt to change the plugs:
 - the plugs & Leads were swimming in oil - so much so that I only removed one plug to inspect it (was ok), replaced the O'rings for the plenum and cleaned the breather. I will have to get all the bits to do the rocker cover gaskets and probibly replace the oil-soaked plug leads in the process.

Thanks for your help :y,
P.
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: MutantCav on 02 March 2008, 19:56:58
If the gaskets were changed fairly recently and are already leaking badly...you seriously need to clean out the breathers and maybe the throttle body too...otherwise it will just keep happening :)
Title: Re: Misfiring V6 2.5 during acceleration only.
Post by: JamesV6CDX on 02 March 2008, 22:28:38
I would check plugs, leads, then DIS, in that order

When I once had a miss, I pulled a few leads, and they looked fine, so I Dismissed them,

It's only when Ronnie Mc B persuaded me to pull no. 6 lead, and I found it in 2 bits, that I found the problem ;D