Revs fluctuating while coasting?

gav525 · Post by **gav525** » Tue Dec 04, 2012 8:29 pm

Been trying to do a bit of research on this today but haven't confirmed anything yet so was wondering if anyone else had suffered the same?

Basically the car is fine while driving along, revs stay where they should etc, but when I let off the throttle to start slowing down, once the revs get to a certain level they drop right down. Now I know this is normal as the other half's 1 series coupe does the same, however where her revs stay still, mine bounce up and down a bit and fluctuate maybe a few hundred rpm(between 600-900rpm). Hadn't been bothering me until today when they dipped so low the car stalled, which was a minor inconvenience.

Any ideas or experience with this anyone? I've been reading various things from torque converters to idle control valves. Going to check the whole air intake tomorrow when I get a chance just to check for any leaks, but I'm pretty stumped after that?

Horizon · Post by **Horizon** » Tue Dec 04, 2012 9:30 pm

Hi
Im guessing its a petrol ????
The term is Hunting. It could be caused by an idle valve or a few members have had trouble with the intake hoses splitting after the MAF / throttle body, or any vaccuum hose, these splits can be easily missed under inspection.
Some mechanics spray easystart on suspected parts when the engine is running,if there is a split the engine vaccuum wIll suck it in and increase the revs.
maybe a member with this problem in the past maybe a better help

gav525 · Post by **gav525** » Tue Dec 04, 2012 10:32 pm

Thanks for the advice there, not a bad idea with the easy start! Will give it a go tomorrow if a visual inspection doesnt give anything away.

And yes, sorry should have said. It's a 2002 3.0i Sport which has been LPG'd, will update my signature to reflect this now

stevox5 · Post by **stevox5** » Tue Dec 04, 2012 11:25 pm

Hi
Check the air intake boot from the airmass meter to the throttle body very closely where it splits off to the idle valve this is the smaller diameter pipe and is very common to split.
Just changed mine .

Gazzi c · Post by **Gazzi c** » Thu Dec 06, 2012 9:16 pm

Hey might sound odd but mIne was doing same thing mainly after booting it turned out it was the fuel filter despite having a full service history it still had the original fuel filter on it with the 2002 production date on it been fine since I changed it

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