Hi,
I have a 1996 Escort 1.8 Zetec which has an intermittent idle speed problem. When the fault occurs the idle speed fluctuates between 800rpm and 1200rpm approx, you can hear the engine rev then drop then rev etc. When the fault doesn't occur the engine has a consistent rpm that doesn't fluctuate. Also, on occasions when you drive then come to a stop the revs stay at nearly 2000 rpm and the only way to get them back down is to put the car in first gear, let the clutch out slightly, then put it back in neutral. This usually works.
Also, the car feels very juddery when you put your foot down, it feels like a dodgy plug lead but i'm not sure. I know it could possibly be a flat spot but the car isn't very smooth even at low speeds. The guy i bought it off (workmate) did say he thought it was holding back a little so i don't think this problem has always been there. I had it serviced when i got it (approx 18 months ago) including cambelt, oil change, plugs, fuel filter, air filter but it made no difference. It's done 117,000 miles, and i don't really want to start buying parts to guess what the problem may be.
Does anyone know if replacing any of the following might cure the problem?
Plug leads
Idle speed sensor on gearbox
Oxygen (Lamda) Sensor (The exhaust does pop a bit too)
If you can help in any way, it would be appreciated.
Thanks.
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First, I would take the idle speed control valve off, and give it a good clean out with solvent. It isn't unknown for the valve to stick.
Your juddering *might* be plug leads. Measure their resistance, and watch the running engine in the dark for further clues.
Any small holes or leaks in the exhaust *might* be responsible for the popping.
I agree with your point with regard to diagnosis by part replacement. I think that, where possible, diagnosis should come before part purchase and replacement - it is usually cheaper.
Number_Cruncher
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Thanks for the reply, ill give the idle speed valve a clean and see if it makes a difference.
With regards to the juddery performance it defo didn't do it before, just checked with work colleague.
Thanks again.
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I'm having a simliar problem with my 98 S reg fiesta 1.4 zetec s but rather than high revving it seems to drop until the car almost cuts out and actually does now and again - I guess this is to do with the idle speed valve.
As I am not that technically gifted when it comes to cars
a) Where is the idle speed located and is this an easyjob to clean ?.
b) When you say solvent - is this like white spirit type stuff ?.
c) My exhaust is blowing quite a bit could this also be a factor ??
Sorry if the above questions seem a bit retarded but as I say I'm not that knowledgeable about cars?.
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Mr b,
Don't worry i'm not a mechanic either!
a) The idle speed valve on my escort is on the gearbox. Don't know about your Fiesta but... if you look under the car on the passenger side and locate the gearbox, you may see a wire and a black plug connected to it, this is connected to the idle speed valve, at least it is on my escort.
b) I've been told to clean it with an alcohol based solvent that evaporates quickly, not sure about white spirit? Maybe Number_Cruncher could answer that one?
c) Dunno about the exhaust but have you checked all hoses etc for air leaks? Or maybe its a fuel problem causing it to stall?
Like i said i'm no expert by a long shot.
Wrightyl
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I think you are much more likely to find the idle speed control valve on the inlet manifold near to the throttle.
Number_Cruncher
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Thanks for the info i thought it was on the gearbox! Doh! I do think its that which is causing the problems with the car.
Thanks again Number_cruncher
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