Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: Malcolm_D on 27 February 2011, 11:39:02

Title: Misfire at 4000 rpm
Post by: Malcolm_D on 27 February 2011, 11:39:02
I am sure that I have seen a similar thread but cannot find it - sorry if it is a repeat  :-[

Anyway - 2.5 Elite 98, just sorted misfire when revving quickly, new coil pack, HT leads & plugs. The beast now idles smoothly and accelerates well, reaches 60 / 70 mph no problem. When pushed hard and revs reach 4000 she stutters and misfires, drop the revs and she is fine. Ideas please  :y
Title: Re: Misfire at 4000 rpm
Post by: mark.adams on 27 February 2011, 19:36:02
Do the revs ever go above 4000?
Title: Re: Misfire at 4000 rpm
Post by: Malcolm_D on 27 February 2011, 19:56:52
I don't think so. To be honest as soon as it starts to stutter and misfire I have taken my foot off the accelerator, I will do a more thorough check when I drive it tomorrow.
Title: Re: Misfire at 4000 rpm
Post by: davethediver on 27 February 2011, 20:18:30
Does it feel as its been limited possible sensor fault, have you pedal/paper clipped it?
Title: Re: Misfire at 4000 rpm
Post by: Malcolm_D on 27 February 2011, 20:58:38
Will paperclip it tomorrow, the EML did not come on although it has since, went off quite quickly so not sure that this is related.
With regard to engine revs being 'limited' it did not feel as if it was caused by the EM system doing something it ought such as 'limp home mode', it feels more as if something is not working as it should, if this makes sense (if it does it will be the first time in a while that I have made sense!).  :y
Title: Re: Misfire at 4000 rpm
Post by: Varche on 27 February 2011, 20:59:37
Do a paperclip test, good practice.

Maybe a fault with multi ram. Check all your vacuum pipe connections. One of mine was split underneath a u shaped connector at the back of the plenum. Looked fine at a cursary glance.
Title: Re: Misfire at 4000 rpm
Post by: Malcolm_D on 27 February 2011, 21:04:21
Will do, had them all out when I replaced the coil pack and HT leads. Will get back with any further news tomorrow night (hopefully).  :y
Title: Re: Misfire at 4000 rpm
Post by: astroblaster on 27 February 2011, 23:21:13
It could be the crank sensor, in having a simular problem, if you do a paper clip test you will get a code 19 as i have, hope this helps :y
Title: Re: Misfire at 4000 rpm
Post by: Malcolm_D on 28 February 2011, 13:50:56
The plot thickens!
Haven't paper clipped it yet but 'played' on the way to work this morning. Started to 'stutter' at about 3500 revs, put it into sport mode to get above 4000, at around 4000 there was a thump - auto box misbehaving, and the revs dropped right down to almost idle. The display showed a message 'Automatic Gearbox', the sport mode light went off and the car became less responsive, it wouldn't go back into sport mode. Stopped and turned engine off, back to normal when I started her up again.
When I arrived at work I tested the problem by revving the engine when in Park, so gears not engaged, it 'stuttered' from 3500 oneards, no EML showing.
Drives fine when I am not being a boy racer, which to be fair is most of the time.  :y