Ford Fiesta (1995 - 1999) - 1998 1.25 over fueling | Technical matters | Back Room Forum

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Thu 5 Jun 2008 20:46

1998 1.25 over fueling - swanvalley2

hi i am an mot tester who has tested the 1.25 zetec fiesta today.i have come across an unusual emmisions fault.whilst ideling the car runs at around .30 co and 240 hydro carbons which is just outside limits.however at 3000 rpm the cars co level rises to a crazy 12 .08 and hydro carbons 2500 way over limits. the car obviously smokes like mad at this point with the over fueling.i then road tested the vehicle as it belongs to an elderly lady to see if it made any differnce.after an initial burst of heavy smoke the cars smoke level subsided. on my return to the garage however the second emmision test was exactly the same as the first. there are no fault codes shown on my eobd scanner.i am hoping someone has come across this fault.many thanks steve

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Thu 5 Jun 2008 21:25

1998 1.25 over fueling - Screwloose

Steve

A few checks. What's the oxygen sensor signal voltage at idle and 2750? Any cracks/air leaks in the exhaust manifold near the oxy sensor?

If you've got a laser; what's the cat in and out pipe temp? [This is too bad to be a cat alone; but it might be blocked.] It had obviously filled the exhaust with soot which shifted when you booted it!

What state is the air filter in; has it been paddling - look hard for water stains. Test it filter out.

Might be a weird coolant temp sensor effect; but....

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Thu 5 Jun 2008 22:10

1998 1.25 over fueling - swanvalley2

hi thanks for that reply.forgot to add that at the second emmision test the same result ensued. which was a narrow failure at idle but at 2500-3000 very high failure 12.05 co hydrocarbons 2000-4000 gas anylyser choking to death.i was also choking to death with the massive over fueling smell.driving the car again the smoke cleared.same thing happened a third time.i cannot work out why the car would at rest cause so much over fueling but on the road drive relitively normal with no smoke.weird!!!!

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Thu 5 Jun 2008 23:06

1998 1.25 over fueling - mfarrow