Fiesta zetec-s wont rev when cold.

[rb5er]

So I bought a fiesta zetec-s as an eco runabout recently and it is in fine fettle considering its done 144k miles.

Except the last couple of days when i get in the car in the morning it is being a bit funny.

Basically if I leave the car for about 6 hours or so it has a problem whereby it refuses to rev, will give me no power and almost cuts out but just manages to stay alive. Quite a sketchy situation the other morning when I was not expecting it as I pulled out of the junction at the end of the road and held up a car when the power just sapped all of a sudden.

After about 2 minutes or warming it is totally fine and revs freely as it should.

And no I`m not talking about trying to rev the nuts off it when its cold as i dont do that to any car of mine but it hardly even gives me enough revs to pull away.

Any ideas? Thanks in advance.

[Silverbullet767]

Wild stab? I'd say the lambda sensor is goosed.

[Defcon5]

Hmmm, does it sound like a bag of spanners or anything, any other symptoms?

Does the fiesta have a limp mode or anything?

[rb5er]

Sounds normal no loud noises, no warning lights.

My mechanic guy said possibly lambda sensor but he would need the car overnight to test it in the morning and cant look at it till next week.

Was just wondering if it was a common problem or something someone may have come across before.

Thanks guys.

[Defcon5]

If the lambda was duff I would expect a warning light of some description, as it will be reporting values outside the specified range

[rb5er]

Would the coolant temp sensor be a possibility?

[Defcon5]

It could be telling the ECU its -100, so its pouring in fuel like there is no tomorrow, but that wouldnt magically fix itself after a few mins, unless it reads from different sensors after if finishes cold start enrichment

[rb5er]

Hmmmm, bit of a head scratcher.

Maybe I should ask in the Ford forum and see if anyone has had anything similar.

Thanks again

[Defcon5]

The mods will move this to the ford forum anyway when they see it

[Ross1988]

Ask on ZSOC.com they are a great bunch and will help you diagnose.

[Richard-G]

I had this on mine, it only became apparent after I put a pipercross foam airfilter cone on it, the issue is the air temp sender in the airbox, it only happens when the car is on autochoke. I never fixed it after nearly 2 years! But it's just a sensor, so fill your boots!

[vit4]

Exactly the same situation happened with my gf's mum's Megane. PITA to find but turned out to be an air pipe which was split, so might be worth checking the condition of all of them.

However, seeing as it only does it when it's cold that would indicate a sensor of some sort - can't be much more helpful I'm afraid!

[chunkol]

rb5er said:

So I bought a fiesta zetec-s as an eco runabout recently and it is in fine fettle considering its done 144k miles.

Except the last couple of days when i get in the car in the morning it is being a bit funny.

Basically if I leave the car for about 6 hours or so it has a problem whereby it refuses to rev, will give me no power and almost cuts out but just manages to stay alive. Quite a sketchy situation the other morning when I was not expecting it as I pulled out of the junction at the end of the road and held up a car when the power just sapped all of a sudden.

After about 2 minutes or warming it is totally fine and revs freely as it should.

And no I`m not talking about trying to rev the nuts off it when its cold as i dont do that to any car of mine but it hardly even gives me enough revs to pull away.

Any ideas? Thanks in advance.

ODBII ?

[Nick3point2]

I sincerely doubt it is the lambda sensor as lambda sensor is not used during cold start, so will have no bearing on how the engine runs before it's up to temperature.

[rb5er]

Richard-G said:

I had this on mine, it only became apparent after I put a pipercross foam airfilter cone on it, the issue is the air temp sender in the airbox, it only happens when the car is on autochoke. I never fixed it after nearly 2 years! But it's just a sensor, so fill your boots!

Sounds promising, but how do you know this was the problem if you never got it fixed?