Ford Fiesta (2002 - 2008) - 05 1.25 Over-revving at start up

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Wed 23 Sep 2009 11:59
05 1.25 Over-revving at start up - Cookie1983
Dear All,

As I complete technophobe, and being fairly new to car ownership, I would be very grateful for some advice please.

About a month ago, I started up my car and the engine roared with the rev counter shooting up to a little over 3,500 at the usual 1,200 or thereabouts. This problem persisted every time on start up and I had a Ford engineer look at the car ? he attached the ?Ford diagnostic computer? but no fault codes were shown. The engineer decided to reset the codes for the throttle body (forgive me, I?m not totally au fait with the technical jargon) and the problem seemed to temporarily disappear (the engine stopped roaring and over-revving on start up) but a few days later it returned.

I called the engineer again and he suggested that the problem was probably mechanical and fitted a new throttle body, re-programming the necessary codes again. (the Ford computer still was not showing any fault codes). But, just as had occurred previously, for a few days everything appeared to be ?normal? again but the problem then returned. Yesterday I started the engine and the rev counter again went up to about 3,500 revs. I switched off the engine and restarted again, and the rev counter only went up to a little over 1,200. I switched off and turned on again several times, and on the fifth restart the engine again revved up to just over 3,500, dropped slightly to just under 3,000 revs, then peaked again at just over 3,500, before dropping to about 1,200 revs. This all happened within seconds, and would suggest that the problem ? which is intermittent ? isn?t with the throttle body at all?

Do you have any ideas as to what may be causing this problem on start up please? The Ford engineer I have been dealing with has now drawn a blank! The actual drive of the car doesn?t appear to be any different, although I do drive very infrequently so my ?testing? is fairly subjective.

Many thanks!
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Wed 23 Sep 2009 14:12
05 1.25 Over-revving at start up - jc2
For Ford "engineer" read garage mechanic (or more likely trainee).
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Wed 30 Sep 2009 15:02
05 1.25 Over-revving at start up - here come the drums
Have you had your engineer look at the ICV? Idle Control Valve? when these go or IIRC they can get clogged up too, then can cause these symptoms.

The other probability is a dodgy air sensor, although I'm not sure, You might be more successful having a look on the ukfiestanetwork forums.
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Wed 30 Sep 2009 15:26
05 1.25 Over-revving at start up - MikeTorque
As the problem is repeatable, by repetitive restarts, an experienced engineer who knows how to use a laptop & engine diagnostics equipment will be able to analyse and diagnose the problem. The live engine data needs capturing when the problem occurs, a prognosis can then be provided.
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