1.25 Zetec 16v running probs - suggestions welcome

[peanutsc]

Hi hope someone can help with a query. As well as all my non technical relics (you know where you are with a carb and points) I look after a couple of vehicles for friends.

One of them is a 1997 Fiesta Flight fitted with a 1.25 Zetec S 16v engine. It's had running issues on and off but as is quite often the case never messes about when I have it... until today.

The symptoms are cutting out at roundabouts on over-run, poor idle (it hunts) and according to the owner periodic lack of power, which can suddenly sort itself out. Doesn't seem too bad at fast idle.

It had a misfire about 13 months back, so coil pack and leads replaced but continued to have an idling/power problem so I started replacing bits one at a time. I put on a genuine Ford idle control valve, after market throttle potentiometer, then a lamda sensor. The lamda sensor appeared to help and I had the codes reset (even though it hadn't thrown up a light). It's been fine for a year but is now misbehaving as above (apparently the same as before).

What could it be? My thoughts are airflow meter but I did try previously swapping the unit with one from another car with no apparent difference. I don't want to keep throwing money at it blind, so any suggestions welcome....

Many thanks.

[ftz313]

plugs then you know they are good.
Modern engines have 'wasted spark' so the plugs fire together in pairs. i.e 1and4 together and 2and3 together.
Means plugs are firing twice as much as 'normal' thus must wear out more even though recommended intervals are like 20k or something ridiculous.

[peanutsc]

The car has been regularly serviced and is in otherwise excellent condition and low mileage. Plugs fine. I had it today and it started fine and went like stink over a 12 mile run.

What I didn't mention is that I also fitted a crank sensor a couple of days back. After a bit of research on the internet last night it was suggested that after changing any electrical bit the ECU needed resetting, easily done by disconnecting the battery for 20 mins and then taking on a good run so the warm up cycle is properly gone through.

I found a thread where a guy had done pretty much everything I had but to no avail and he was told about the breather pipework on the inlet manifold and some little valve thing in the top of the crank case. I cleaned this but no idea how it's supposed to work or if it's broken. It's about the size of a cotton reel and has a rod and spring inside which just seems to rattle about... it may function based on vacuum in inlet manifold but not sure.

Other thing is that when revved the engine sticks at 1500 briefly before settling to idle at about 800. Not sure if this is symptom of something.

[ChasR]

I would look for a vacuum leak, especially with a lot of things being disturbed. Even on knackered plugs Zetecs will idle (but it will not benefit the coil pack for too long).

I would also clean the ICV out again if it has been used on many short journeys and around town (was it a new ICV?).

[fray-bentos-uk]

I had running problems with my moms 1.25 Zetec, that turned out to be the MAF, try cleaning it first if you are reluctant to throw any more money at it, though as people have suggested, new spark plugs gapped exactly right are always a good investment. I have also heard of coil pack problems with these, though you say you have sorted this previously.

[peanutsc]

Hi folks. The idle control valve was a brand new Ford unit (heard the aftermarket ones were not much cop) just over a year ago. You are right about short runs - this car does quite a few of them so perhaps cleaning the ICV will clear the issue with the revs sticking at 1500 briefly. Due to the low cost of service parts I've been replacing everything on an annual basis anyway, mainly because of the short runs - NGK plugs. Everything is cleaned and gapped and if it's not going to last a year it gets replaced. I strip and clean the braking system too and check everything else. It gets a good going over (probably better than a lot of garages) yet it still buggers about...

After looking at it and cleaning the breather system over the weekend there are no obvious issues again, so it's back with its owner. Hopefully it will be okay but I hate jobs where no obvious fault can be found. At least when you find something broken, the fix is obvious! If the problem persists i'll look at the MAF and see if there is a way of testing it. I'm confident there are no vacuum issues as the problem is not consistent and the car otherwise goes amazingly well.

[rodney]

speed sencer on the gearbox , it causes a few symptoms like stalling when slowing down , revs slow to drop when lifting of the gas or changing gear etc ,

get it plugged in ,

its the part the speedo cable goes into on the box, between box and cable, cheap easy to change part,.

[peanutsc]

Thanks for this suggestion - I've learned something there. Car is still going okay at the moment so will bear that in mind for the next time...