Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: Cameron on 04 April 2009, 17:19:13

Title: Misfire - Please help!
Post by: Cameron on 04 April 2009, 17:19:13
Hey all, I got a maf from Mutantcav last weekend and I thought it had sorted the misfire...but it hasn't, I've also just replaced the o ring seals on the breather bridge/throttle assy - still there   :(

Symptoms: fine when cold (and it's fine at this point - no misfire, good response), as soon as the fast idle disengages, very rough idle and misfiring (especially bad at low revs)

Paperclip test gives (engine not running):

12
135
31
12

Please help, I'm meant to be driving down to Marham next week to track the car and this may stop that happening... :(
Title: Re: Misfire - Please help!
Post by: Welung666 on 04 April 2009, 17:22:22
135 = Telltale checklight voltage low
31 = No engine RPM signal

Dount they could be connected though.
Title: Re: Misfire - Please help!
Post by: RobG on 04 April 2009, 17:43:34
Any trouble starting :question
Title: Re: Misfire - Please help!
Post by: Cameron on 04 April 2009, 17:51:50
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Any trouble starting :question

Nope, she starts fine. :-/
Title: Re: Misfire - Please help!
Post by: RobG on 04 April 2009, 18:03:27
EGR working OK :question
Title: Re: Misfire - Please help!
Post by: Cameron on 04 April 2009, 18:43:33
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EGR working OK :question

I think so, would it not throw an error code if something were wrong? :-?
Title: Re: Misfire - Please help!
Post by: Cameron on 04 April 2009, 20:42:10
Update:

Well I removed and cleaned the EGR valve, the IAV, the MAF and cleaned a load of connections.  Still misfiring...badly.

Took the MAF off again and cleaned the element with a dry cotton bud and reassembled.  Seemed better, but still misfiring...

Went for a drive for fuel, noticed on the way that it seemed to clear after a while at about 65mph, 2500-3000 rpm.

Got 20 ltrs of BP Ultimate and drove back, noticed it cleared again over 2500/3000 rpm...could feel it wanting to go...wee 'spurts' of released power, before clearing and pulling like a train over 3000 rpm.  When slowed down, misfire returned   :-?

Can anyone diagnose this...? :-/
Title: Re: Misfire - Please help!
Post by: Darth Loo-knee on 04 April 2009, 20:45:12
Does this sound like a Dispack problem?
Title: Re: Misfire - Please help!
Post by: Cameron on 04 April 2009, 20:55:08
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Does this sound like a Dispack problem?

It may well be, I replaced the dispack last year for a secondhand one from ebay...I also moved it to the scuttle with some longer leads.

The only thing is I think it was fine until I did the timing belt...
Title: Re: Misfire - Please help!
Post by: Darth Loo-knee on 04 April 2009, 20:59:59
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Does this sound like a Dispack problem?

It may well be, I replaced the dispack last year for a secondhand one from ebay...I also moved it to the scuttle with some longer leads.

The only thing is I think it was fine until I did the timing belt...

Oh, did you have a cam locking kit when you did the cambelt? a mate of mine used to get a flatspot about 3000rpm, I checked his cambelt and it was out two teeth, I put it right and the flatspot went. Check your timing is right first as last mate :y
Title: Re: Misfire - Please help!
Post by: Cameron on 04 April 2009, 21:03:24
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Quote
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Does this sound like a Dispack problem?

It may well be, I replaced the dispack last year for a secondhand one from ebay...I also moved it to the scuttle with some longer leads.

The only thing is I think it was fine until I did the timing belt...

Oh, did you have a cam locking kit when you did the cambelt? a mate of mine used to get a flatspot about 3000rpm, I checked his cambelt and it was out two teeth, I put it right and the flatspot went. Check your timing is right first as last mate :y

No, I have to admit I didn't have the locking kit and it was a mare to do.  Had to do the old TDC on cyl 1 thing...3 attempts later and it was sorted.  But surely if the timing was causing this problem, it would do it when cold too?  :-?
Title: Re: Misfire - Please help!
Post by: Darth Loo-knee on 04 April 2009, 21:10:38
Think to start with I would be rechecking the timing with a Cam Locking Kit mate, then go from there
Title: Re: Misfire - Please help!
Post by: Cameron on 04 April 2009, 21:14:11
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Think to start with I would be rechecking the timing with a Cam Locking Kit mate, then go from there

Thanks mate, but unfortunately I don't have one and I'm travelling down south on thursday... :(
Title: Re: Misfire - Please help!
Post by: Darth Loo-knee on 04 April 2009, 21:14:46
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Think to start with I would be rechecking the timing with a Cam Locking Kit mate, then go from there

Thanks mate, but unfortunately I don't have one and I'm travelling down south on thursday... :(


Where are you?
Title: Re: Misfire - Please help!
Post by: Cameron on 04 April 2009, 21:20:25
A long way-a-way, east of Inverness, northern Scotland.

Can you not still accurately check the timing using the markers?
Title: Re: Misfire - Please help!
Post by: Darth Loo-knee on 04 April 2009, 21:24:20
A little to far to pop up then mate  ;D

I personally wouldn't do it without the locking kit, you really only have about 1/4 of an inch tollerance. You may have been lucky I suppose.
Title: Re: Misfire - Please help!
Post by: Cameron on 04 April 2009, 21:41:51
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A little to far to pop up then mate  ;D

I personally wouldn't do it without the locking kit, you really only have about 1/4 of an inch tollerance. You may have been lucky I suppose.

Here's hoping, doesn't feel like it atm...
Title: Re: Misfire - Please help!
Post by: Cameron on 05 April 2009, 10:53:49
Do these symptoms sound like a faulty dis pack?
Title: Re: Misfire - Please help!
Post by: jonathanh on 05 April 2009, 13:05:38
depends where you are over next weekend mate but if you are in the midlands you can drop by and check the cam timing with my kit (providing its around) and we can arrange something.

In my experience performance is very sensitive to cam timing.  Since I changed my belt, performance has improved: bank 3,4 was only out by about 3mm on the guage!



However, gut feel is that it's more likely to be dis pack than cam timing.
Title: Re: Misfire - Please help!
Post by: Cameron on 05 April 2009, 13:16:39
I'm going to be near Aylesbury next weekend, visiting friends before going across to Marham and the trackday.

Just started her up and like before, when cold, she was lovely...good response, smooth with little evidence of misfiring (although possibly a tiny bit).  Then as the fast idle dropped off misfiring becoming more apparent, until at normal idle the misfire is obvious...

This is doing my head in, always just as I'm getting ready for the trackday...last year it was a crank sensor.  >:(
Title: Re: Misfire - Please help!
Post by: RobG on 05 April 2009, 14:48:11
You`ve either got a faulty dispack or one of the plugleads is breaking down. Have you tried having bonnet open with engine running when it`s dark to see if there`s any signs of arcing/tracking :question
Title: Re: Misfire - Please help!
Post by: Cameron on 05 April 2009, 15:06:45
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You`ve either got a faulty dispack or one of the plugleads is breaking down. Have you tried having bonnet open with engine running when it`s dark to see if there`s any signs of arcing/tracking :question

No, i've not tried that.  I've relocated the dispack to the scuttle, someone has mentioned on the ABS forum about the dis pack needing to be bolted to the block for earth...

*Edit - I made up some earth leads using bolts through the dis pack and wired them straight to the battery neg terminal.  No difference.