Hi
I have a 98 'R' Ford Fiesta with air conditioning. When the air conditioning is on, the idling speed oscillates most of the time between 800 and 900 rpm, and the other day oscillated between 500 and 1100 rpm.
With the A/C off, the car is normally steady, or may oscillate between 900 and 950 rpm.
I am presuming a sensor somewhere has gone? Anyone got any ideas?
All the best
Simon
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Ther have been a couple of TSB's concerning erratic idle speeds, and having the a/c on may be exagerating things. What engine size is it? Let me know and I'll see if their is a relevant TSB.
The idle-up is controlled by the PCM altering the fueling, so there is no sensor as such, all controlled by the infamous ECU.
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mine does the same once every now and then, but generally only when the engine is cold.
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I had the use of a Fiesta Ghia for six weeks, and I found the air-con to be a pain in the neck. There was a noticeable power drop when it was on and I would never want it in a car with a small engine. It is a breeding ground for bacteria and not a patch on an open sun roof. I know some people love a/c but I think it's just junk technology waiting to expensively go wrong. The info that the a/c must be used for 30 min a month to keep it in condition is buried on page 52 of the handbook. I doubt if more than a small % of owners ever read that far, so there must be a lot of second hand Fiesta's out there with mullered a/c systems.
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Dave N
Thanks for the offer to look up the TSB's, very much appreciated. It's a 1.25 Zetec.
If the route cause of the problem is the ECU then I might just have to learn to live with it!
All the best
Simon
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Tom
Thanks for taking the time to reply. I had a company car with air con, and so chose the air con on the Fiesta after that. The main reason is we have a spaniel, and in the summer it is, literally a life saver for him. I run the air con over the weekends, and generally turn it off on the boring office commute. The company car was a Renault Laguna - the only time the air con failed was on the hottest day of the year, last year. 38 C I think it was!!
Thanks again
Simon
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I ran a Fiesta Ghia CVT with a/c for about 40K miles and seem to remember this sort of erratic idling as fairly normal and no problem at all. Probably also varied substantially more on some occasions but a touch on the accelerator put it right. Great car, incidentally, and my second Ford CVT without any problems. I can only assume people who have problems with the 'box are maltreating them in some way.
Aircon definitely a plus in the car and with the heated front screen made winter driving much more pleasant on start up.
David
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oh ho ho
I had a Fiesta with CVT box, and took great care of it, and drove it very carefully...
And i had the gearbox oil changed at every service
but the elastic bands snapped and wrecked the gearbox case
and therefore i can only report that you are very lucky
very very poor technology
it should be cheap to fix, but isnt!
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My 1.25 Zetec Fiesta CVT was an R-reg company car and gave no problem to me or the guy who took it over (as far as I know, he told me he was very pleased with it for the M25 crawl).
The Escort CVT I had previously was P-reg and completed around 75K in around 14 months with no problems but when the guy came with the new Fiesta and took the old one away he did say there had been problems with the 1.6 Escort and CVT. A female colleague with one started to have some selection problems around 45K but they were adjusted away. I think she bought hers off the company in the end.
All three were mostly used on motorway or long distance commutes with the M25 Heathrow area crawl 3-4 times a week rather than in town, short journeys. Maybe that is relevant.
David
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There was a TSB issued in 1997 no. 131, but that should have been solved by the time yours was made. It covers 1.25 zetec build code VM to VA inclusive, those fitted with Siemens (brown) injectors. It involves reprogramming the PCM with the Ford FDS2000 machine, time is down as 0.1 hour.
I gave you a bum steer earlier. It does have an idle valve controlled buy the PCM. It is on the front centre of the engine, looks like it's behind the exhaust manifold, with wires coming into it from the RHS as you peer in the bonnet. If you turn the a/c on, then pull the plug to this, see if there is any difference to the idle speed. It should be around 950 with the a/c on, 850 without, and about 500 if the a/c is on, but the valve not operating. You can also check for voltage at this plug with the a/c on. The supply side should have a black or black/yellow, the earth side violet/yello. If there is voltage, but the idle isn't increasing then the valve is US. If no voltage, probably problem elsewhere. Check the earth side also. but as it uses the same earth as the injectors it should be ok. Don't apply voltage to the plug or short its terminals otherwise you'll be down to the dealer on a flatbed for a new ECU.
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Dave N
Thanks for info - much appreciated. I peer under the bonnet and take a look.
To be honest, this might all be a little too complex for me, but I should able to use the information to limit the financial damage and get a dealer or something to look at these specific points.
Quality of the information is outstanding, I and really do appreciate the time you have spent on this one!
Thanks to you, and all other respondents.
All the best
Simon
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