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Lumpy idle and hesitation at low revs

Started by Sihayton, September 24, 2015, 07:57:28 AM

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September 24, 2015, 07:57:28 AM Last Edit: September 24, 2015, 08:02:46 AM by Sihayton
My Galaxy 2.3 has a problem at low revs where it seems to have a lumpy idle which is between 700-800 rpm.

All is fine when you start it from cold and the revs are over 1000rpm but as soon as the car is warm it's lumpy and if you're driving along with low revs in town it hesitates and jerks about until you either drop it down a gear or get over 1000rpm. It's absolutely perfect over 1000rpm with no hesitation at all.

I've changed the ignition leads and I'm changing the spark plugs today. Does anyone have any other pointers?

I've changed the plug and they don't seem to have made a difference sadly.

Does it misfire/ hesitate when driving with the engine under load?
Always learning..... Often by mistakes!


I think the coil packs on these can break down after extended mileages and cause misfiring but I would expect that kind of fault to manifest itself under load regardless of the revs. If it's just low revs it's possible you have a sticky idle speed control valve or something like that, you can clean 'em out with brake cleaner but how long that will work for before it plays up again I don't know.
Always learning..... Often by mistakes!

I'll give it a clean over the weekend and see if that helps.

I thought coil pack too but it runs great over 1000rpm - I might just stick a new one on just in case

Might be worth looking at the throttle butterfly and body as well, if it's worn or gummed up that could cause problems.
Always learning..... Often by mistakes!


Small update: Cleaned everything and no change. Unplugged the MAF and the engine continues to tickover with no change. Would this point towards a faulty MAF?

It could but I wouldn't go buying a new MAF sensor just because of that. The fact that it only is a problem at base  idle speed or just off idle would point towards an idle speed control valve not working properly, or a worn throttle body allowing air to pass the butterfly even with it shut. It could even be a split/ disconnected vacuum or breather hose or something like that.
Always learning..... Often by mistakes!

After much head scratching it would seem the problem is finally sorted.

The car was lazy starting yesterday and as I was driving I had the ABS light come on along with the airbag light and a bong from the dash, pulled over turned off the car then couldn't get it restarted. Managed to get one of the guys from work to come rescue me and after a bit of googling came across the battery fuse box problem.

Checked mine and one of the cables had been overheating and when one of the lads was looking at the offending cable he managed to snap one of the fuse box metal connectors.

Had a brand new one delivered today, sorted the cable and fitted the fuse box....... no more lumpy idle. Went out for an extended test drive..... no more hesitation at low revs.

I would never have thought that was causing the issue but all seems sorted now  ;D