Ford Fiesta (1995 - 1999) - 98 1.4 Intermittent misfire

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Sat 25 Apr 2009 12:00
98 1.4 Intermittent misfire - John D
My sister-in-law's engine has been giving intermittent misfiring problems for a few months. The car's mileage is 92,000 and appears generally well maintained.

The spluttering can happen at any time any place any speed. It can run for a couple of days, doing long journeys without doing it.

It has been recently serviced...new plugs, filters etc. She asked the mechanic to bear this fault in mind, but it was no different after the service.

2 days ago she limped into a motorway service area & called the AA. He changed the ignition coil & HT leads. The car ran perfectly for 70 miles, then did it again.

I've had a good look at the rubber vacuum hoses - no fault found. Also wondered about dirty connections onto sensors/coils, but can't see anything obvious.

Any suggestions will be most welcome.

Thanks

John
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Sat 25 Apr 2009 12:58
98 1.4 Intermittent misfire - bell boy
yes
get the fault codes read
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Sun 26 Apr 2009 13:54
98 1.4 Intermittent misfire - John D
Thanks...I should have thought to do that. I've now borrowed a code reader, unfortunately no fault codes were recorded.

I also looked at the earth strap between bulkhead and engine, which looked a bit green. It fell apart in my fingers, so I remade the connection. Any thoughts as to whether intermittent connection of this earth would stack up with the fault?
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Sun 26 Apr 2009 15:50
98 1.4 Intermittent misfire - bell boy
ive never seen a good earth strap here to be honest,they are always shot,i assume its an extra earth for a good lambda signal.
no faults is good.
fault not rectified is bad
youve covered most things i would suspect im afraid
i would like you be checking earths,battery terminals and plug fittings,fords are usually good with coming up with a sensible code on this year, i can only suggest you code read it again to confirm you did it right
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Mon 27 Apr 2009 22:28
98 1.4 Intermittent misfire - John D
code reader still says no faults.
Battery terminals, earthing straps, plug leads OK.

Last night car did 150 mile run. First 20 miles - perfect. Next 20 spluttering, next 55 perfect, then random occasional splutters for rest of trip. I'm still baffled by this one!
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Tue 28 Apr 2009 11:46
98 1.4 Intermittent misfire - Javalin
is it spluttering at a particular point? For example after changing gear, or at low revs? Have you checked the condition of the plugs & the crank case breather? Any smoke out the back whilst its spluttering?

James
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Wed 29 Apr 2009 00:13
98 1.4 Intermittent misfire - John D
Hi James

As I understand, the splutter happens at any point...sometimes at a steady high speed cruise, sometimes decellerating, crawling in traffic etc...no pattern.

The plugs have been renewed....made no difference.
Crankcase breather is as clean as a whistle....no oil, mayonaise or anything. I blew though all the pipework myself, just to be sure.

Must ask Sis-in-law to check her mirror when it splutters, in case it smokes.

John
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