Ford Fiesta (1995 - 1999) - yr 1998 - Zetec 1.25 CVT Misfire

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Wed 17 Oct 2007 12:07
yr 1998 - Zetec 1.25 CVT Misfire - DaveC
My wife's 98 Fiesta 1.25 Zetec Auto has a misfire/stutter when driving but the problem doesn't show up when the car is stationary (or on the Ford diagnostic testbed)

The car momentarily looses power and then picks up again and drives OK. (until the next time)

The car has been recently serviced by Ford and the CVT has been checked and is OK.

The speedo needle always "flickers" slightly when the car is being driven but I haven't noticed it going to zero or anything during tha actual "stutter"

Any ideas?

Edited by Dynamic Dave on 17/10/2007 at 13:26

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Wed 17 Oct 2007 12:28
Zetec 1.25 CVT Misfire - Screwloose
Dave

These faults can be tricky to find. When does it do this hesitation? Hot? Cold? Constant speed? Accelerating?

When did it start doing it? Anything change around that time?

These can suffer from water getting into the ECU plug and the fuel-pump plug.
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Wed 17 Oct 2007 12:55
Zetec 1.25 CVT Misfire - DaveC
The fault mostly happens when the car is up to running temperature and cruising at constant speed (above 25mph) although it can also happen on acceleration from a standstill.

Nothing particularly changed when the problem started, but I haven't had the car that long.

When I bought the car the problem wasn't there and just started happening occasionally after about a month. The problem got progressively worse so I took it to my local Ford dealer. They tried to find the fault but it seemed to "cure itself" (The mechanic told me they didn't really do anything except clear the fault logging in the ECU)

After getting the car back it was OK for a month or so and now it's got worse again.
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Wed 17 Oct 2007 13:46
Zetec 1.25 CVT Misfire - Screwloose
Dave

"Clear the fault log in the ECU?" What codes had it logged?
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Wed 17 Oct 2007 14:00
Zetec 1.25 CVT Misfire - DaveC
Hi Screwloose,

They said it had registered a fault on the fuel pump but had checked the pump and it checked OK.

The mechanic said it might be an intermittant short on the wires going to the pump but he checked as much of the harness as he could and couldn't find any damaged insulation or other evidence of any shorting.

He cleaned all the connectors, put it back together again, and the fault was gone.

As far as he/the garage was concerned the "fault" was cured but he did tell me that he didn't think he'd actually fixed anything and felt it was more luck than anything else!
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Wed 17 Oct 2007 14:16
Zetec 1.25 CVT Misfire - Screwloose
Dave

Get them to drop the fuel tank and check the plug on the fuel-pump for corrosion. It's only accessible from underneath with the tank lowered.
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Wed 17 Oct 2007 14:21
Zetec 1.25 CVT Misfire - DaveC
Thanks Screwloose,

It's going back to the garage on Thursday. I'll insist that they do this and hope that cures it.

I'll post a message to let you know how it goes
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Thu 18 Oct 2007 10:12
Zetec 1.25 CVT Misfire - Kingpin
Have you checked the HT leads, I had a misfire on the same car a while ago and it turned out that one of the ignition leads (or possibly coil pack) was faulty - it idled fine but trying to pull up a hill or put engine under load caused a misfire as the ignition was breaking down under load.
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Mon 22 Oct 2007 12:13
Zetec 1.25 CVT Misfire - DaveC
Hi Kingpin,

The problem is mostly when the car is travelling at about 35 - 40 mph even on level ground where I think the engine is under a low load.

The Ford garage checked the coil pack when it was first in there and gave it a clean bill of health.

Dave

P.S the car was in the garage again last Thursday and Friday. They replaced some hose on the fuel tank because it was "pinched" but the car is just as bad as before it went in. Car is back in the garage today for further checks.
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Thu 25 Oct 2007 22:36
Zetec 1.25 CVT Misfire - wicked_buffy
It's a longshot but credible.....has the cambelt been changed recently (probably not as the interval is 100Kmiles/10 years)? My son's car Fiesta suffered in the same way as yours - a check on the timing revealed that the timing was significantly out following a cam belt change by the local garage. It took a few weeks to get to the bottom of it. I bought the timing tools for £15 and did it myself; problem totally cured.
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Mon 12 Nov 2007 14:32
Zetec 1.25 CVT Misfire - DaveC
An update - Problem solved !!!
Got the car back from the garage 2 weeks ago and wife has been driving it with no problems.
After checking just about everything the garage checked the crankshaft position sensor and found it was mis-aligned. They cleaned it and re-fitted it properly and the car runs fine.
Why a mis-aligned crankshaft sensor would cause the car to mis-fire intermitently I have no idea (I would have thought it would mis-fire continuously) but it does seem to have cured the problem.
Anyway, all fingers and toes are crossed that the problem stays away (makes driving a bit difficult) and MANY MANY thanks to POLAR FORD in Runcorn and Screwloose and Wicked_Buffy for their help.
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