1998 fiesta 1.25 zetec - Fast Idle - gasspringmaker

Can someone shed a bit of light on this for me.??

I have a 1998 Fiesta zetec , when i pull up to a junction the revs pick up

to 2000 rpm then drop between 2000 and 1500 rpm then drops down to tick over.

I was told it could be the idle control valve , so replaced that and was still the same.!!.

Then took it to a local garage and put it on their diagnostics machine to be told it could

be the map sensor on the bulkhead.

So i replaced this today but it still has made no difference.

Any advise would be much appreciated.

1998 fiesta 1.25 zetec - Fast Idle - alastairq

I, too, have this issue. [1999 1.25 zetec fester]

As yet, I haven' replaced anything....[except two new front tyres].

I presumed,because recently I'd changed my 'driving style' [drove somewhere else]....that maybe the engine management system had adapted to suit?

Of course, now I'm home, drivng style is back to 'normal'...

Seriously though....check out the power steering pressure sensor [somewhere onthe high pressure PS line?]

It 'appears' the connecting plug can become corroded, or damaged, especially if recently negotiated lots of water or grit.

This sensor works mainly to detect severe steering movements at low speeds/low revs/tickover. Such an increase in PS pressure might stall the engine, so the sensor tells the ECU to boost the revs a bit.

Also worth checking if the air con pump is actually disengaging when swtiched off?

[this also has a sensor to tell the ECu to load up to compensate for the increased drag]

For my normal gearchanging, the lack of rapid rev drop isn't noticeable.

{as above, I presumed the ECU had 'learnt' I like to block change my gears? ]

Or..am I just a confused auld fahrt??

1998 fiesta 1.25 zetec - Fast Idle - alastairq

Just want to add.....................how come the revs drop only after the wheels have stopped turning?

Not before [tried coasting, doesn't do a damned thing to the high tickover!! grrr!]?

1998 fiesta 1.25 zetec - Fast Idle - gasspringmaker

It just seems that when you slow down coming up to a junction it does the same if you slow down in third gear then dip the clutch or dip the clutch and coast up to the junction.

The revs just pick up then die down when it wants to.!!

1998 fiesta 1.25 zetec - Fast Idle - gasspringmaker

Thanks for the info, will have a look.

I've just read a similar thing on another site so its worth a try.

Is getting to me now as i've replaced three parts and is still the same.

Checking that connector does add up though when you think about all the water and muck sprays up there.



1998 fiesta 1.25 zetec - Fast Idle - elekie&a/c doctor

A few items to check here.When replacing the idle control valve,it is best to disconnect the battery so that the ecu can "re-learn base settings".Check operation of the vss.(vehicle speed sensor).This is bolted in to the gearbox housing at the rear,near driveshaft.Early cars with a cable drive speedo,have the vss connected in line and can give problems. .Later cars with electronic speedo also have a vss,but if the speedo works ok ,then the vss is ok.Also check that there is enough slack on the throttle cable where it is connected to the butterfly housing.One other item to check ,is the 3 pin connector to the throttle position sensor.Make sure it is clean with tight contact pins.

1998 fiesta 1.25 zetec - Fast Idle - unthrottled

I had this problem. It appeared to be solved by loosening the butterfly from its spindle and re-centering it, and cleaning up the throttle body housing with carb cleaner. It appeared that the butterfly wasn't always fully closing on the overrun. Quite why the revs managed to drop to normal idle while the vehicle was stationary but not moving remains a mystery.

I'd hazard a guess that the ECU doesn't permit the ICV to fully close whilst the vehicle is moving-perhaps for emissions purposes?


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