strange idle on 'M' Fiesta - Jake Harrop
My girlfriend has a 'M' registered Fiesta (1100 I think) which is prone to cutting out when you take your foot off the gas - it does this when the engine is either both cold or warm (though more when it is cold).

In addition, it has more recently developed an odd habit of revving upto about 3000 rpm of it's own accord, sometimes staying there for a few seconds and then dropping back down to normal idle, at othertimes the rev counter needle appears to bounce as the revs drop off and then immediately pick up again, only to drop once more when the 3000 mark is attained. This behaviour is only exhibited when the engine is cold.

Having once owned an old XR2 that did similar things, I suspect that these issues may be the fault of a duff automatic choke. Is anyone in a position to confirm my suspicions - she is taking it to the garage on wed to get it MOT'd and would like to get it fixed then, but is worried about just asking the garage to 'fix it' without having an idea of what may be wrong.

Thanks

Jake
Re: strange idle on 'M' Fiesta - Adam Going (Tune-Up Ltd)
Jake,

Quite a regular problem on late Ford systems. Firstly, you don't have a "choke" as such - the engine management system is constantly monitoring engine temperature, among other things, to control mixture, ignition, and idle speed.

The most common cause of these idle stability problems is the Throttle Position Switch (TPS). They can be faulty or just out of adjustment, but even a new one may not be to spec. Sometimes it is possible to obtain correct setting of TPS by filing out the fixing holes into small slots, allowing some movement rotationally. All this assumes that all other basic settings and functions are to spec. The garage will need to be fully conversant with engine management diagnostics to get this one sorted, or you will need to contact a specialist.

Regards, Adam
Re: strange idle on 'M' Fiesta - Jamie Hopkins
Hi,

My girlfriend had exactly the same problem with the engine cutting out, she hasn't got the one where it revs itself yet though.

Once it has cut out you have to leave it for a couple of minutes before you try to start it as it will not work for at least 3/4 minutes!!

Anyway she took it into the ford garage and paid £50 for them to put it on the testing machine and it passed with flying colours,

What is that all about????
Re: strange idle on 'M' Fiesta - John Slaughter
The issue usually is that if it's an intermittent fault , it probably will check out OK, unless the fault shows up during testing. The one fault I had on my Vectra was fixed by my local dealer based on the description, which was as well as it didn't show up on the ECU. You need a decent dealer, or a guy like Adam, who is clued up on how these systems actually work, and based on the fault description can usually have a good idea what is causing it.

Regards

John
Re: strange idle on 'M' Fiesta - andy sampson
My girlfriends M reg 1.1 fiesta used to cut out and not restart straight away, put in a new set of spark plugs and this has not happened now for 1 year!, dont know how old the plugs were but think that they should be changed once a year.
 

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