3dr Cosworth misfire help...

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Feb 24, 2009 | 05:46 PM

boXXer

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GASH!

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From: UK

3dr Cosworth misfire help...

Hi all, just wondered if anyone could give me a hand or some pointers in how to sort my missfire.

Car was setup last year, and ran fine all summer. Havnt used it for a while, so got it out a couple of weeks ago for a small run. It now has a misfire when on boost.

It was missing @ 15psi, so i changed the plugs to some iridium items, and it was exactly the same. Gapped them down to .8mm and it "moved" the misfire up the boost range to about 19psi. So gapped them down to .5mm, and the misfire moved up again to 26psi.

i have changed the plugs, leads, rotor arm, cap, coil, crank sensor and phase sensor and it hasnt changed anything.

Is there anything else thats worth trying? it seems to me that it has a weak spark, as the smaller you close the gap, the higher boost it reaches.

Cheers for any advice.
Mike

Feb 25, 2009 | 03:58 AM

tabetha

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From: uk

A "group a" coil is worth a try if not already, the std coils really are that crap, also check supply at coil to make sure it is full supply and not got a duff supply.
tabetha

Feb 25, 2009 | 09:18 AM

IANS2RST

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From: SHEFFIELD

also check the alternator output under load

Feb 25, 2009 | 10:18 AM

jon@work

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how old is the fuel in the tank ?
it does go stale

Feb 25, 2009 | 11:55 AM

boXXer

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GASH!

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From: UK

Quote:

Originally Posted by tabetha

A "group a" coil is worth a try if not already, the std coils really are that crap, also check supply at coil to make sure it is full supply and not got a duff supply.
tabetha

Its a brand new "group A" coil mate.

Feb 25, 2009 | 11:55 AM

boXXer

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GASH!

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From: UK

Quote:

Originally Posted by jon@work

how old is the fuel in the tank ?
it does go stale

new fuel mate

Feb 25, 2009 | 11:58 AM

boXXer

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GASH!

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From: UK

what does the ignition amp do exactly?

reason i ask is, it seems the smaller the plug gap, the harder the boost "blows out" the spark, like it has a weak spark.

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Feb 26, 2009 | 08:22 AM

boXXer

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GASH!

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From: UK

Feb 26, 2009 | 08:27 AM

daviddunlop83

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From: Holywood, N.ireland

I had something similiar on my standard 3 door. When driving normally it was fine. Soon as went onto full boost it misfired and put engine management light on.

Turned out the plug that connects to the crank position sensor was f**ked and not contacting properly. The pins inside where spread apart. Bent them together before i could get a new plug and fixed the problem

Feb 26, 2009 | 03:26 PM

#10

boXXer

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GASH!

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From: UK

i think i may have fixed it. Did what you said, and cleaned ALL the multi plug connections, and bent the tabs over a little, and it seems to have dissapeared. Will update tonight....