Xsara idling @ 2900 ! maybe cured with WD40

FAC51 · Post by **FAC51** » 31 Jul 2007, 15:31

ok a quick description and hopefully someone can help me out:
xsara 1997 1.6 16v

i have an annnoying problem as the subject suggests ... without reason the idle speed will suddenly start racing (and judging by the fumes running very rich) and won't subside unless the ignition is switched off and the car is restarted a good while later ... sometimes the idle speed will eventually get back to normalty-ish running around 1250 rpm ..... it is worst when driving at slow speeds or in traffic ... a 250 drive down the motorway the other day and it ran perfectly, i occasionally coasted to see what the rpm's were and they were around 850 ... todat ran faultlessly in traffic then as i was pasking up ... the revs suddenly started racin g again .... coming back to the car 10 mins later and it stalled when reversing .. after this it is always a nightmare to get it started again ... no doubt because it is running so rich ....
so ....
can anyone point me in the right direction as to what it could be ?? and the costs to put right ... the previous owner had the sensor on the radiator hose changed about 18 months ago .. according to the mechanic this solved the same problem but this sensor is unlikely to go again .. is it ?
any under bonnet pics would be most helpful ....
thanks in advance
Rob

Post by **admiral51** » 31 Jul 2007, 16:54

think something similar is set out in this topic

http://www.frenchcarforum.co.uk/forum/v ... sc&start=0

colin

FAC51 · Post by **FAC51** » 02 Aug 2007, 13:45

First of all thanks for the tips and info within the forum .... be9ing a thicko i couldnt find the stepper motor .. the pic i saw on here was a 1.4 ... mine is a 1.6 ... anyhow ... gave the inlet area a big blast of WD and the engine is running fine ... still idling perfectly when hot .... revving it etc and the rpm drops straight back down... this is all whilst its still sat on the driveway tho .... anyhow .. if it is a leak in the inlet manifold(s) how would this effect the idle speed and mixture once the engine warmed up ... just curious . .. will keep you posted in case someone else has the same hassles
cheers
Rob

Post by **CitroJim** » 02 Aug 2007, 21:45

Hi Rob,

The WD40 has found you an air leak and in doing so cured it

On a temporary basis I guess

Idle speed is controlled by the Idle Control Valve by adjusting the amount of air entering the engine on idle. The more air, the faster the engine idles. What is hppening is that the leak is effectively bypassing the Idle Control Valve. It'll be trying to regulate the idle but it'll be at the extreme end of its control range and will have given up in dispair because the air leaking in cannot be controlled by it.

The leaking air is unmetered and will have a small effect on idle but comparatively little during running under power.

FAC51 · Post by **FAC51** » 03 Aug 2007, 02:26

Hi there Jim ... second time of test idling in the drive the engine was idling like a madman and would only be slowed slightly when drowning the pipes and intake area in WD40, if indeed i do have a leak somewhere would this also cause the engine to run very rich which it does when idling at high speed ?