I've got a fiesta 1.3 finesse, 98 s - reg. it's a really good car, but....
it loses power. not all the power, about 15% of it at various times and only for about 10-15 seconds or so.
e.g crusing along the motorway, keeping up with traffic (you know the speed), then the "power loss" kicks in and the engine can be heard slowing down, and the speed drops thro 70 down to about 65, then after 15 seconds it all picks back up and normality returns. it used to do it once in a while (once a month (?)) and only on motorways (although it's easier to spot it then due to constant speeds). now it's started doing it loads and at all speeds, you can actually feel it losing power and then surging back.
it happened before, and the garage checked it and found all the exhaust readings were out, replaced the lambda probe and it was fine for about a year.
this time it's been to a ford garage who've checked all the readings, checked the engine management system and can't find anything wrong.
anyone got any ideas before i ask them to start replacing parts one at a time?
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Partial fuel blockage?
Had something similar with an Avenger, once.
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Purdey or Gambit?
Or was it Steed?
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Muck in the carb, its stripdown time. But only if you have got a good supply of carb cleaner and some high pressure air.
Andrew.
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Unfortunately no carb to clean on this one! I'd hedge a bet on the Lambda probe being a likely suspect. Another one could be a sticking carbon canister purge valve. On the car is a carbon filled canister which 'soaks up' fuel vapour vented from the tank. At certain operating times this canister is purged into the inlet tract and burnt under controlled conditions. If the valve sticks excess vapour can be drawn through the canister uncontrolled. There is also a possibility that the Exhaust Gas Recirculator (EGR) valve may be sticking upsetting the fuelling at certain times. At higher speed cruising the valve will be wide open and may be occasionally sticking particularly if cheap fuel has been regularly used.
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Has it got air con?. Is it the comp. cutting in and out. On a small engine this could be enough to drop the speed!!
Matt
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By 98 the air-con should switch off when you go to wide open throttle and only cut back in as you ease off.
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I have an N-reg fiesta but the mark 4 like yours. I have the same problem but mine loses power for about the first 5-10 mins of every journey then goes fine. Because of this I never experience power loss on the motorway as I live 5-10 from the nearest motorway! I know this is no help whatsoever but hey...
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does it still have low power if you have your foot hard to the floor? if so i'd suggest the lambda isn't the problem, as at full throttle the ECU works in open-loop mode, deliberately overfuels, and ignores the value from the lambda sensor.
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I have a similar problem to the original - just purchased an R reg Fiesta Flight 1.3 with an Enduro (?) engine. I think it could be just the fuel filter, but the engine chugs as if starved of power. It also cuts out when idling - at first, I thought it was the fuel, so re-filled at a different garage, but there's no change, and the chugging is getting worse now...
Any information would be grateful.
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I would go with Fuel Filter (quick job!), and then check if there was some sort of 'Air Flow Sensor' / 'Air Mass Meter'. No experience of this engine (apart from helping to service a friend's last week!), but almost identical symptoms struck my Cavalier (1995) last year. Appreciate very different beast, but from 'monthly' hiccups on Motorway, it became a daily occurence. I was spraying carb cleaner towards the throttle body every trip!
Eventually changed the Air Flow Sensor (£50 from breakers) and appears to have sorted problem once and for all.
Jon
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