Fiesta 1.25 zetec - fuel system problems - Neil McDyer
1.25 Zetec 1997, 94,000 miler. Sudden chugging down motorway and loss of speed, replaced fuel filter for the first time and used injector cleaner. Stopped all the chugging- 90% better.
Problem is when blipping accelerator quickly from idling, revs seem to do the opposite and die down for longer than usual say half a second, picks up after the initial air intake. Worse when cold, but once going along it's virtually unoticeable. revs die if the accelerator is pressed too quickly at low revs. Speed dies/limits when accelerating through 4500rpm then drops to 65-70mph and it's fine again (been doing this for few months while accelerating through exactly 4500, so high it's never been a major prob, suspected filter).
Just renewed badly worn Plugs for NGK's, Bosch Leads, Fuel & air filters. Absolutly no different!
Is this a dodgy air mass sensor. Very consistant fault never cuts out and is drivable if I take it easy pulling away with enough rev! (1500)
Any ideas whats holding me up ??
Thanks in advance, Neil
Fiesta 1.25 zetec - fuel system problems - Andrew Moorey (Tune-Up)
It is possible that the airflow meter is causing the problem but I'd go for a lazy O2 sensor at that mileage. If you were to put one onto a 'scope you would probably find its switching rate was down to about 10Hz. Using the injector cleaner may have cleaned up its act a bit but these sensors must be viewed as a consumable item at around the 40k mark depending on how the vehicle has been used. i.e. shopping and school runs will kill it far, far quicker than pounding the motorway.
Andrew


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