Martay

Hi,
I have a 1997 fiesta mk4 1.25 and it has an over revving problem thats confusing me.
When moving, if you dip the clutch or put into neutral the revs will drop to ~1500rpm, then shoot up to 3500rpm. The only way to stop this is to put into gear or turn it off. Also while moving at a constant speed, the car will 'cruise control'.
I have replaced the throttle sensor, idle control valve and Mass Air Flow sensor to no avail. I have also had the ECU reset, and had the car looked at by an auto-sparky, and he couldnt see a cause to the problem.
Before this started, it would idle lovely at 1000rpm, but now sits at ~1200rpm most of the time.

I was wondering if anyone has heard of this problem before, and could suggest an answer.
Many thanks

martysmartie

iTrader: (1)

Check the clutch pedal switch connector, this is located on the clutch pedal, this can get knocked off especially if you have huge feet like me.

Martin

mp0109

check inlet for leaks
need to get the car on an emission tester to see what the emissions are like?

James998

Check the pressure switch wiring on the o-s corner behind the bumper for the power steering. If the wires are corroded off that will be (atleast part) of your problem.

qudos

dose any1 have a mk4 fiesta half rollcage 4 sale?????? or were do i shop 4 1.

pampy

Have a similar issue with my son's 2000 (W) reg 1.25 zetec Fiesta.
Basically we've replaced the Throttle Position Sensor twice now (first time with a pattern part then with a genuine Ford item). Initially the problems were cured by fitting the pattern part and resetting the ECU by disconnecting the battery for 30 mins. However, the problem then returned - car idles when stationery at 1200 rpm, then "hunts" between 1900 and 2500 rpm if you blip the throttle. Put the car in gear and just move slightly and the revs drop back to idle again. When moving it's as though it has "cruise control" and wants to drive itself. We've now fitted a new genuine Ford TPS, and rectified a problem with a collapsed vacuum pipe which was causing the revs to stick at 3000rpm but still have the problem. Immediately after reconnecting the battery the car will idle at 1000rpm, but once you touch the throttle it's up to 1200 and then hunting again between 1900 and 2500rpm. I've checked the wiring to the sensor and the voltages - 5 volts in from the ECU, one pin to ground and the output back to the ECU on the centre pin at closed throttle is 0.2 volts (I'd read somewhere that over 0.4 volts can cause problems).

Please, has anyone got any other ideas ? My son is driving me mad moaning about having to keep spending money on it and I just don't know where to look next.

Thanks for any help or advice anyone can offer.

martysmartie

iTrader: (1)

Check the clutch pedal switch as I mentioned above as you say it stops when putting into gear and moving slightly this actuates this switch, it does seem like the TPS but having replaced it twice and getting the correct readings it seems unlikely.

1200 RPM is also a fast idle (Unless on cold start of course)

Martin

pampy

Martin,

Thanks for your suggestion - interestingly it doesn't have a clutch pedal switch fitted, I suspect they were removed after a certain date ?

The plot thickens !

Any other ideas ?

andytwonames

Did this ever get resolved? I have the same problem.

BLU

iTrader: (1)

Simple and very common problem. It is, 99% of the time, the idle control valve is dirty and sticking. Take it off, blast through with some carb cleaner (you'll be amazed at the black shit that comes out) re-fit and hopefully job done!

pampy

Yes, all sorted. Turned out to be a split in the vacuum hose underneath the inlet manifold. Repaired that and the fault was instantly cured.

Worth removing all the vacuum hoses and checking them closely - I'd missed the split in a previous inspection !!!

Good luck

andytwonames

Ah, good. Thanks for that.

The local garage (I trust them) had it for MOT and took a look for me. They took the TPS off and cleaned id (no charge) and said to replace it if it made no difference.

It made no difference so I replaced it.

It still made no difference!

Garage now says to drive the car for a while and the ECU will learn!

I will have a dig about with the vac pipes and see what gives.

Cheers

Andy.

andytwonames

OK, can you point me to where that might be? I know where the TPS is as I replaced that.

Cheers

Andy.

BLU

iTrader: (1)

Depends on engine

On 16v Zetec engine its the silver cylinder behind the dipstick

On 8v Endura E engine its the silver cylinder in the middle on the left hand side of the oil filler cap.

HtH

andytwonames

Got it, ta.

Going away for a couple of weeks so I will have at it when I return.

Bobby_dw

Hi All,

Has anyone managed to solve these problems?

I have a 2002 Fiesta Endura-E J4J, it started a cpl of years back with cruise control and idling erratically at 1500 rpm. A step on the clutch or coming to a full stop would return the idle to 1000. Every now and then the ECU would throw the TPS code, and it used to disappear after a throttle body thorough clean.

Lately the TPS code is on all the time, the erratic revving comes every now and again, mostly when its cold outside.

I changed the TPS, ICV, checked the Power steering pressure switch connector and it looks to be in good cond. On that note, when idling if i move the steering wheel, the idle will drop by 200 rpm almost.

I feared water ingress on the ECU at some point but these problems went through the entire summer, so im guessing that's not it.

Any ideas? Could a faulty power steering sensor be causing all this fuss?

Many thanks.