Hi,

I'm new to this Ford fault finding lark as was after some advice for fixing my mother-in-laws car.

She has a 2003 1.4 16v Duratec Fiesta with 143k on the clock. I bought her the car before xmas and gave it a full service including plugs, leads and coil. and was running perfectly.

Now a few weeks later the car will not idle (hot or cold) It runs fine at all revs but just stalls as soon as you back off the throttle.

Ive read loads of threads about this over the last couple days and I've checked some of the common faults....

Checked the vacuum hoses, found the one that goes from the inlet manifold to the block to have a large split in it, changed that.

The other 2 vacuum hoses that go to the fuel pressure regulator and some sort of solenoid both look ok.

Checked the throttle body, all looked ok and was not sticking. Changed it for a spare off eBay, It has a 2S6U-CC fitted, replaced it with a 2S6U-DC (which i believe is the latest compaible version) Still the same.

Not throwing up and fault codes, at least not that I can see using Forscan.

Disconnected the battery for 10 mins, no change.

Other things that people in other threads have mentioned are the TMAP sensor, a switch on the clutch and a vehicle speed sensor. Anyone have any advice on what I should look at next?

Thought I would post an update on where I have gotten....

When I left the car it would not idle, cold or hot, not even if I gently lowered the revs to tick over before backing of the throttle completely. It would stall straight away.

Tonight I thought I would drive it home to my house so I can work on it more easily, This is about 30 miles through A roads and 2 towns. When I got home I tried to get it to tick over gently lowering the revs again, now it would idle with the lights off.

I read earlier today about the PCM having to re-learn the idle settings after you has reset the KAM (which I had done by disconnecting the battery for 15 mins previously.

The recommendation was to turn everything on (lights etc) and let it idle. I did this and after a while I could gently rev it and it would not stall, the revs still dropped too low but it just recovered.

I took it for a couple small drives over the next hour and left it idling in-between and now it will idle perfectly, wont even drop below idle speed even from high revs with every light on I can find, max blower the lot.

For good measure I checked the response of TMAP sensor using Forscan on my phone and a Bluetooth OBD2 adaptor. Pressure with the engine off showed the same as barometric pressure as it should (1.02Bar) with the engine running 0.3Bar(ish) which looks sensible. Intake temperature was showing 33 degrees C, Its about 0 degrees out but the engine is hot so I'm assuming this is ok.

So it looks like the original fault was the vacuum hose from the inlet manifold to the crankcase PCV valve. Changing the throttle body and resetting the KAM left the PCM needing to relearn the idle settings. Seem ridiculous that the car would not idle at all until this process has happened but it appears to be the case so far.

The proof will be tomorrow when I fire it up cold!

After disconnecting throttle body for what ever reason, a initialisation procedure is required.

It was -5 out this morning and it fired up and idled a dream!

Howsit,

I have a 2004 Ford Fiesta 1.4 and I'm also having an issue with the car not holding idle (hot or cold ). It's starts and drives perfectly , but when you don't Accelerate It cuts off. What can be the issue???