Do you know your car's MoT and mileage history? Our user profiles will show you for FREE | No thanks
'98 Fiesta Zetec 1.25Si - Over Revs - Scott The Honk
OK so basically here is my problem, (I know this has been covered in other topics but i would like a few questions answered! I have done my research and previously searched the forum for some answers, so please don't blast me search results cause that isn't helpful to any one!)

Just before i went away when we had the serve weather in the UK my car started over revving. By this i mean, i would be say doing 40 MPH in 4th Gear and i would be at about 2,500 RPM. I would then put the clutch down and take my foot completely off the accelerator. However the engine would maintain these revs and then build on them sometimes building up to 4,500 RPM. I would be doing about 15MPH and slowing down and the revs would be maintained until i came to a stop at a junction where the revs would either continue or they would slowly decrease.

I am aware that firstly this could simply be the accelerators linkage getting stuck. I am not sure if my model is linkage or cable and i do not know how to check this so would appreciate some help on this one.

Secondly i have followed several tests to see what is wrong with the car and would like some feedback on if these have solved the problem for any one else?

also i think i should point out that i have also tried going along at 30MPG or so and having the clutch fully down for say 1/2 a mile and then just pressing the accelerator to bring it up to 3,500 RPM. Then releasing completely. The revs would maintain and then build!

TO try fix the problem i have already disconnected the battery for 30 minutes and then plugged back in, left running idle for 10 minutes. revving for 2 minutes at 1,200 RPM then driving for 15 miles. This did seem to have some effect and at the moment it only seems to hang the revs for a few seconds or build them before then returning to fall back to neutral revs. I am therefore going to be disconnecting the battery for a longer term (over night) and then following these procedures again to see if this helps!

I have also heard that it could be the potentiometer and that ford would need to reqird this and it would take about 0.3 man hours to do.

Can any one give me any advice on any of these issues or suggest a way that they have fixed the problem?


If i continue to run the car in this state, will i begin to wear down the clutch and therefore have to replace it, as i assume as the revs will be carrying over that i will start riding the clutch with gear changes?

Spelling tidied up and subject line tweaked - PU
Ford Fiesta 1998 Zetec 1.25Si Over Revs - normd2
have a friend sit in the car with the engine off and get him to press the accelerator a few times. You look under the bonnet as he's doing this and you'll see the throttle cable moving the linkage. Spray this with wd40 or similar and see if it helps.
Ford Fiesta 1998 Zetec 1.25Si Over Revs - Screwloose

This isn't the cable and DO NOT try adjusting anything, you'll just mess things up big-time.

The ECU isn't "seeing" that the throttle is shut and is leaving the idle control valve in the open [running] position until the vehicle comes to rest.

The throttle potentiometer SIGNAL tells the ECU whether the throttle is shut or not and that is where the problem lies.

Corrosion of the engine wiring plug [under a plastic cover at the back of the engine] isn't unknown. Worth a check.

Anything more than that requires a specialist to investigate as this is a highly sophisticated idle sensing system and I'm not explaining comparative ratch voltages on a forum.
Ford Fiesta 1998 Zetec 1.25Si Over Revs - normd2
I guess I'm stuck in the days where if you couldn't fix the car you just got a bigger hammer....
Ford Fiesta 1998 Zetec 1.25Si Over Revs - Screwloose

The posts crossed-over there; I hadn't read yours when I posted mine. My warning was based on the OP.
Ford Fiesta 1998 Zetec 1.25Si Over Revs - normd2
so might be worth a skoosh (sp?) of oil on the linkage then?
Ford Fiesta 1998 Zetec 1.25Si Over Revs - Screwloose

Won't hurt; won't help.
Ford Fiesta 1998 Zetec 1.25Si Over Revs - Scott The Honk
Is it worth having a look myself or should i just take it to Ford?

Also no one has answered whether disconnecting the battery for a pro-longed period of time could help the situation and make the ECU relearn its values?

Also is it going to ruin my clutch to have the engine revving all the time when i bring the clutch back up (i.e riding the clutch)
Ford Fiesta 1998 Zetec 1.25Si Over Revs - jc2
Disconnecting the battery will do nothing and,yes,slipping the clutch will wear it out.When a new one is fitted,drive it normally and the ECU will learn the base settings(idle & full-throttle positions) in about 10 mins.
Ford Fiesta 1998 Zetec 1.25Si Over Revs - Scott The Honk
Any ideas on how much this work is going to cost me and if its possible to do it myself?
Ford Fiesta 1998 Zetec 1.25Si Over Revs - jonnydy2j
Hi all.

I am also getting the same problems with my 1.3 1998 Fiesta. Has anyone found the solution yet or is it deffinatly a Ford job. I will try spraying the linkage with wd40 but I dont think that this is the problem as the throttle doesnt seem to stick open.
Ford Fiesta 1998 Zetec 1.25Si Over Revs - jc2
It's a nylon lined cable-lubrication is more likely to attract dirt and cause problems.

Ask Honest John

Value my car

Amount to borrow
Sorry. The minimum loan amount is £1000
To pay back over

My credit score

Best available rate 9.20%

Total repayment £9,304.93

Total cost of credit £1,804.93


60 monthly payments

Apply now

Representative example

The Representative APR is 13.2% (fixed) so if you borrow £7,500 over 4 years at a rate of 13.2% p.a (fixed) you will repay £199.21 per month and repay £9562.20 in total.