2000 X Ford Fiesta 1242cc 16v Zetec - Idle speed problem

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Fri 19 Apr 2019 23:07
2000 X Ford Fiesta 1242cc 16v Zetec - Idle speed problem - Roland T

After a journey of about 50 miles I left a dual carriageway and noticed that the car was idling too fast at junctions, initially only dropping to about 1,500 rpm but later only to 2,000 rpm.

After breaking my journey, the car stalled backing out of the parking and I was unable to restart it. It turned over fine (almost new battery) but showed little interest in firing.

I left the car for about 90 minutes but could not restart it, so disconnected the battery for a few minutes to see if that would help. After several attempts, the car eventually fired but the idle speed gradually increased over about 10 seconds until it reached 4,500 rpm, when I turned the ignition off.

I'd be very grateful for any suggestions on what might be going on and how to remedy this.

Thanks,

Roland.

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Sat 20 Apr 2019 06:45
2000 X Ford Fiesta 1242cc 16v Zetec - Idle speed problem - elekie&a/c doctor
Check the coolant level is up to the max mark. Does the heater blow hot? Does you car have a temp gauge ? Some models don’t.
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Sat 20 Apr 2019 10:52
2000 X Ford Fiesta 1242cc 16v Zetec - Idle speed problem - Roland T
Check the coolant level is up to the max mark. Does the heater blow hot? Does you car have a temp gauge ? Some models don’t.

Thanks for your reply.

Coolant level in the expansion tank was around the minimum, so I topped it up to the max before trying to start it. Started normally and ran normally for 2-3 mins. Tried starting again but got previous normal turning over but with the engine sounding like it wasn't trying to fire.

Heater was working on Thursday but it was hot yesterday, so heater was turned off and now I can't run it to check. However, I did notice that when I first had trouble re-starting it yesterday, even though I'd driven 50 miles, after ~5 mins in a shop the temp gauge was registering but lower than I'd expect the temperature to have dropped in that time.

Could it be a faulty temperature sender unit?

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Sat 20 Apr 2019 11:03
2000 X Ford Fiesta 1242cc 16v Zetec - Idle speed problem - elekie&a/c doctor
My theory is exactly that . Could be the engine coolant temp sensor reading incorrectly. If you have access to a scanner that reads live data , this can be compared to actual values.
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Sun 21 Apr 2019 00:03
2000 X Ford Fiesta 1242cc 16v Zetec - Idle speed problem - Roland T

No scanner but I do have another car of the same age with the same engine!

I swapped the temperature sensors and sure enough, the problem was solved on one car but transferred to the other. I'm surprised that even on a car launched in 1995, the coolant temperature sensor output is so critical to basic running of the engine but there you go.

I managed to source a new sensor locally just before closing time and I'm back on the road.

Thanks for your help - much appreciated.

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