BigJimnyMeet (North) 2024 (12 Jan 2024)
14th July 2024
Parkwood Nr. Leeds
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Random rough idling, getting worse
- RockmanRock
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In summary, it has started missing a beat when sitting at idle - like a misfire, but there is no warning light. It's a pretty violent miss, as the shake carries through to the whole car. It started doing this more and more over a couple of weeks, and when it went in the garage, they replaced the plugs (which weren't that old since I last did them). This cleared it up for another couple of weeks, but it has no started doing it again. The symptoms are:
- * Only does it when the engine is warmed up
- * Seems to happen more often with load at idle i.e. aircon on
- * randomly misses a beat, no set interval. maybe about once a min, sometimes a few times?
- * gets progressively worse over a few weeks
- * does not cause the check light to come one, and neither has it put any error codes
- * no issues driving
- * went away with new sparkplugs for a while, then came slowly came back
Any ideas?? I was thinking maybe 02 sensor issue, or something like that causing a buildup on the plugs? Other alternative is a weak HT lead or coil - I've experienced failing coil pack on another car - but I would have thought that would happen regardless of engine being hot or cold, and wouldn't explain why new plugs fixed it for a couple of weeks. I'm keen to get it sorted as I have a big trip coming up and can't be worrying about it cutting out once outback.
Advice appreciated,
Cheers,
Rob
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Might be best to check them.
Former owner of Little "Ooky", who has now started a new life in Shetland
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Had the same on my MotoGuzzi.
Some days it would just cut out when I came to a junction, ran like a pig, but fine when moving.
Other days, or when ever I messed with it, e.g. new plug caps: the idle speed was higher and perfect.
Never put the diagnostic light on either.
Swapped one of the coils out and the problem went away.
Can't remember how I decided which coil it was though........
My jimny has an irregular miss at idle, seems the same symptoms as the 'bike, I've just changed the plugs: no difference, so I will get another coil when I see one cheap on eBay.
If it suddenly breaks, go back to the last thing that you did before it broke and start looking there
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- RockmanRock
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Former owner of Little "Ooky", who has now started a new life in Shetland
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- gazert
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RockmanRock wrote: I would have thought a position sensor failure would cause bad idle across the board, not just when cold? And the change of plugs did fix it for a while. Although I suppose it could be the heat getting to the cam sensor...
Usually happens when the sensor heats up.
Ive been driving at 70 mph and all of a sudden things have give very erratic.. stop for 5 mins, restart and proceed at slow speed noproblem.
Changed the sensors, (wasnt sure which one it was) and the problem went away.
Coilpack sounds a good candidate though
Former owner of Little "Ooky", who has now started a new life in Shetland
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- gazert
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My nephew was quoted £1200 to replace the engine on a polo after he had had a mess.
Symptoms were missing at idle and after 10 15 mins.
Lumpy running and cutting out.
They told him it was his cam belt had jumped a tooth and caused internal failure that was not at that stage catastrophic!
One second hand coil pack later and it ran as sweet as a nut!
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