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Random rough idling, getting worse

  • RockmanRock
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13 Apr 2011 09:24 - 13 Apr 2011 09:25 #14945 by RockmanRock
Random rough idling, getting worse was created by RockmanRock
Hi all, can anyone pls help shed any light on a problem with idling I am having on my 06.

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
Last edit: 13 Apr 2011 09:25 by RockmanRock.

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13 Apr 2011 10:26 #14947 by ooky_123
Sounds similar to a sensory issue .. Crank or Camshaft sensors give similar issues when hot. although these do tend to also happen when you are driving.

Might be best to check them.

Former owner of Little "Ooky", who has now started a new life in Shetland

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13 Apr 2011 17:21 #14967 by facade
Coil.

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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13 Apr 2011 20:34 #14995 by RockmanRock
Replied by RockmanRock on topic Re: Random rough idling, getting worse
Thanks for the replies. I can get my hands on an ignition coil cheaper (and swap it over quicker) than a O2 sensor, so I guess I'll try that first and see what happens. If not, it's still a good small part to fit into the spares cubby on board...

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13 Apr 2011 22:40 #14997 by ooky_123
Not an O2 sensor .. Crank and cam position sensors. they retail for about £50 each in the UK

Former owner of Little "Ooky", who has now started a new life in Shetland

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13 Apr 2011 23:00 #14998 by RockmanRock
Replied by RockmanRock on topic Re: Random rough idling, getting worse
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...

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14 Apr 2011 07:33 #15006 by gazert
Replied by gazert on topic Re: Random rough idling, getting worse
I agree sounds more like a coil pack to me.

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14 Apr 2011 13:44 #15016 by ooky_123

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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14 Apr 2011 20:27 #15053 by RockmanRock
Replied by RockmanRock on topic Re: Random rough idling, getting worse
Thanks for the feedback all, hopefully the new coilpack will turn up today, so I can do some swapping over the weekend and report back.

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25 Apr 2011 05:23 #15439 by RockmanRock
Replied by RockmanRock on topic Re: Random rough idling, getting worse
Sorry for the delay in posting resolution, haven't had much spare time to get it done. Anyway, swapped out one coil and it still played up, so swapped the other instead, and problem seems to be gone (only test drove for about 3 hours so far, but was coming up within 45min before). FYI, tested the resistance on duff coil, and it was within the specs in the workshop manual so no obvious clues. Tried replacing the rear one first (thought it may have been the more likely to wear out due to heat) but it ended up being the front.

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11 May 2011 06:47 #16182 by RockmanRock
Replied by RockmanRock on topic Re: Random rough idling, getting worse
Got round to checking the bad coil more thoroughly; after pulling off the boot, had two hairline cracks as can be seen in the image. These were missed before, as they were hidden under the boot rubber. All that trouble from two tiny cracks

Attachment DSC02820.jpg not found

Attachments:

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  • gazert
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11 May 2011 11:33 #16196 by gazert
Replied by gazert on topic Re: Random rough idling, getting worse
Glad you got it sorted!
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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