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850 hesitation and mis-fire? 850 1996

Hi - ive (still!!) got a 1996 855 2.5 10valve (which since i've fixed ABS issues, lvarious electrical faults, stopped an anyoing rattle from the rear brakes and fitted a new cat and repaired the tail pipe exhaust hanger - oh! and fitted a shiney new tail pipe finisher since mine fell off or was nicked) everything seems to have been ok

Until....2 days ago when without warning it i got in it, started it up and as i drove it hesitated but was better at higher revs, It did the same a few hours later when i drove again, and the next morning from cold was so bad it stalled as i tried to accelerate.

The plugs seemed ok (Bosch multielectrode -been in since last December) but i put in a set of new Volvo plugs and also number 1 lead was corroded at plug end and the insulation was very brittle and fell apart - the leads, cap and rotor arm were new from GSF about 3 years ago. I replaced this with a 2nd hand one from local Volvo breakers (Lee Valley Motors - they're really quite good!!)

I cleaned out throttle body, where flame trap goes (mines been removed for years by the way) and the auxilary air valve thingy, and all the vaccuum hoses seem good.

It drove ok, a bit hesitant, but cleared (down to carb cleaner i suspect) and actually drove better.

But a few miles later it hesitated again but not as bad - seems worse under light throttle, and again this morning from cold, but no where near as bad.

Before i rush out and buy leads on the assumption that the GSF ones are rubbish after a couple of years (the reason i replaced them if i remember was fact car at time on original leads seems to be a bit hesitant/surrering slight mis-fire) is there anything else i should look at??

oh!! No engine management light has come up - i remember it did on a mates
'96 T5 even when one of the little vaccuum hoses split AND when it was started after plug change and one lead was left off by mistake....)

Thanks!

Kevin

ps!!

oh!! getting worse now!! and seems to be missing at cruising speed too

and started stalling, especially on pulling away at lights etc. Not too clever especially as it's automatic!! it's annoying me more than the drivers behind me!!

Not really driveable now

dont think this can be HT leads and definately worse when hot and no engine management light on

Fuel pump relay? Coil?

Help!!

pps - does anyone know if the fuel pump relay is the same as any others so i can substitute??






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New 850 hesitation and mis-fire? [850][1996]
posted by  kev  on Sun Aug 26 04:15 CST 2007 >


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