intermittant misfire

2.2 I5 20v turbo - 315 bhp
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afhgus
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intermittant misfire

Post by afhgus » Thu Aug 05, 2004 7:34 pm




I've expereinced some misfires and rough tickover and noticed the aircondtioning running at max lowers the idle and feel there is some link between the to. Of course I had the car checked at specialist who could find no problem at all. Frustrating as the intermittant problems are to detect has anyone expereinced similiar. Car runs well now but I'd like to get to the bottom of the problem.
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afhgus
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Post by afhgus » Fri Aug 06, 2004 6:37 pm

Has anyone had any electrical gremlins that caused a misfire? :roll:
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Greg_S
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Post by Greg_S » Fri Aug 06, 2004 9:15 pm

have you managed to log any fault codes? checked the coil pack impeadance/resistances?

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afhgus
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Post by afhgus » Sat Aug 07, 2004 2:01 pm

That all sounds very technical. QST had the car for a week and could find nothing. I just have a hunch the air con does something. Had it at max the other day and when i came to switch off engine noticed uneven idle/slight misfire.
M690LYY Volcano black,130000 miles,standard,everyday transport, new rear discs, new door trims, replaced radiators x2, front/rear shocks(OE) + suspension bushes, recent alarm, undersealed, new exhaust/head gasket, pulls like a train. for sale soon
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Post by Greg_S » Sat Aug 07, 2004 8:22 pm

does it settle if you blip the throttle? is the idle a steady surging up and down?

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afhgus
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Post by afhgus » Sun Aug 08, 2004 10:30 am

Not always. The idle may drop down to 500 rpm and hover between 500/700 unevenly accampanied by a small misfire. After 30 mis drive yesterday with aircon at 2 the above happened. 8 hrs later car perfect with nice smooth ible and no misfire!
M690LYY Volcano black,130000 miles,standard,everyday transport, new rear discs, new door trims, replaced radiators x2, front/rear shocks(OE) + suspension bushes, recent alarm, undersealed, new exhaust/head gasket, pulls like a train. for sale soon
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Greg_S
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Post by Greg_S » Sun Aug 08, 2004 11:12 pm

could be in part down to a boost leak i would think. Also worth checking your lamda probe out, if it cant get a could signal the engine will hunt up and down in a sweeping motion over a couple of hundred rpm trying to get the fuelling right.

tickover should be at around 800-850rpm also.

Greg
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afhgus
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Post by afhgus » Mon Aug 09, 2004 2:57 pm

Have had a new lamda probe. Its not a big problem. And only come to light when I use air con at x2. ie in this hot weather. I shall get mention all this to QST when they next have the car, thanks for the advice though. :ban:
M690LYY Volcano black,130000 miles,standard,everyday transport, new rear discs, new door trims, replaced radiators x2, front/rear shocks(OE) + suspension bushes, recent alarm, undersealed, new exhaust/head gasket, pulls like a train. for sale soon
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