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Mitsubishi Carisma 1.8 1996 - Misfire - Fixed #

Posted by Shane gray on November 29, 2013, 8:57 pm

Year of Manufacture *: 1996
Engine Size and Code *: 1.8 4g93

Hi,
Got misfire on this one, I have tried to scope primary on coils and I don't seem to be able to get a pattern with picoscope at all.. There are two coils with each one on a plug and ht leads leading two others, the coils have 3 wires each on them 1 thick 1 slightly thinner and the 3 thinner again. Are these negative or positive switched coils ?
Can't read fault codes as don't have scanner that will comm with it.
Any help please?
Shane

Re: Mitsubishi / carisma

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on November 29, 2013, 9:19 pm, in reply to "Mitsubishi / carisma"
Mark Carter

Scope for an enable signal (switching signal) from the ECU, check power/earths in the normal manor.

Mark

Modern cars, Its all wizardry and witchcraft

Re: Mitsubishi / carisma

Posted by Shane gray <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3442' width='330' height='300' border=0 style='border:none;'> on December 1, 2013, 7:29 pm, in reply to "Re: Mitsubishi / carisma"
Shane Gray

Hi mark,
After looking at wiring diagram it seems these coils have an ignition amplifier built in . Can you test these the same?
Shane

Re: Mitsubishi / carisma

Posted by Lee Mackintosh <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1348' width='330' height='300' border=0 style='border:none;'> on December 1, 2013, 8:21 pm, in reply to "Re: Mitsubishi / carisma"
Lee Mackintosh

Could you not scope secondary instead by using a couple of extension ht leads.

sounds similar to the later rover k series setup. At least you could scope 2 of the secondary ht outputs but I suppose its going to be the coil on plug cylinder at fault.

Is it not possible to scope current on these 2 ht output coils?

I've never really had much luck scoping ignition systems to find intermittent misfires unless its really severe then I can notice a fault.

Re: Mitsubishi / carisma

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on December 1, 2013, 9:17 pm, in reply to "Re: Mitsubishi / carisma"

That's why I said

>>> Scope for an enable signal (switching signal) from the ECU, check power/earths in the normal manor.<<<

And not scope the primary switching signal.

Mark

Modern cars, Its all wizardry and witchcraft

Fixed #

Posted by Shane Gray on December 6, 2013, 9:30 am, in reply to "Re: Mitsubishi / carisma"
Edited by board administrator December 6, 2013, 2:44 pm

Hi,
Checked earth and lives to coils and it seemed like live was dropping out so traced back to ignition switch and cleaned contacts.
Anyway it was still intermediately misfiring so scoped cam and crank and went on road test, after about 25 miles (it always takes an age to play up when monitoring) the mil came on and misfire present, watching waveform and you could see cam signal dropping out. Live and earths ok so replaced cam sensor and all ok.

Shane

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