'N' Reg Mondeo 2 litre T.C.i. Petrol injection.
Problem with an engine misfire between 2000 - 2500 r.p.m In top gear this is approx 25-30 m.p.h and therefore occurs whilst town driving mainly under light load conditions. Any ideas what this could be?
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Any ideas what this could be?
I would have thought that being in 5th gear is too high a gear for 25-30mph. Does it do the same in 3rd or 4th gear at the same speed?
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A slow switching lambda sensor may cause this as it will cause periods of excessively weak mixture. Fouled injectors could be another cause of light throttle mixture at such low engine speeds. Try and save 5th gear for higher road speeds.
Andrew
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Simplicate and add lightness!!
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Thanks for the replies so far. I should have said that it does this in any gear at these revs.
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Had a similar problem a few years ago from my M reg si mondeo.
Cured by new plugs and HT leads
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Similar problem on my 2.0 R (90,000 miles)Mondeo was cured with new HT leads. There's a thread about this, somewhere. I was advised that it's a false economy to use none-genuine replacement leads.
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I'm experiencing the same issue with my 1998 2.0. I've replaced the plugs and the HT leads and this has cured most of the problem but it's still misfiring a little. Does anybody have any other suggestions?
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I am also experiencing slight hesitancy/surging at 1500 - 2000 rpm at very light throttle settings but only during the warm up period. So from cold after perhaps 0.5 mile the symptoms occour and may last for another mile or two. My daily trip is such that I only notice this happening during the low speed parts at 30mph in 4th or 20 - 25 in 3rd gear. Going back to plugs and leads, my leads are original and the plugs are Motorcraft fairly new (set to 1mm). Surely misfiring of plugs occours mainly under load? My 96 mk 1 1.8 (72k) will happily run at motorway speeds for hours with no problems. I use Halfords semi synth 5w-30 so it hope fully it is not a problem with cam follower hydraulicking. On very warm days it does not appear to occour. However the lambda sensor is original and there is a small amount of black crud inside the throttle body. Has any body had problems with the ecu temp sensor being intermittent? I was wondering if this could be the problem.
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Further to yesterday's post (a day when I didn't use my car). SWMBO realised there was a hedgehog in the garage, so started the car, moved it out, turned it off, chucked the hedgehog out, and after some minutes started the car and moved it back inside.
The point to all this being, that although it is summer, when I went out in the car last night, it started ok then ran roughly presumably because of the 2 'cold' starts and was obviously 'over fuelled' and took a few hudred yards to get back to normality.
Now we have been warned of this problem many times on this website, so how come my neighbour who has 3 cars to juggle about on his drive, starts and stops them without a care and never has any problems?
I'm left wondering if my Mondeo tends to run over rich when cold, although it doesn't feel rough normally whilst warming up. I have checked the cold and hot resistances of the ecu temp sensor and they agree with Haynes, also an ecu inspection for dry joints and subsequent reset as in Haynes has made no difference to the light throttle misfire.
Is there any mileage in kidding the ecu that the temperature sensor thinks it is warmer than it is by adding a parallel resistor?
Any thoughts would be welcome.
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"so how come my neighbour who has 3 cars to juggle about on his drive, starts and stops them without a care and never has any problems"
My (new) Rover 800 was v had for this.
Mercedes 260E (1988) never had any problems)
2001 1.6 Fiesta - no problems
Sons 1994 1.1 EFI Fiesta - no problems.
Imo if you have a dirty MAF sensor (oil/dirt) may make things worse. Clean with a carburettor spray.
Also use fuel injector cleaner - a sticky injector will tend to overfuel when cold as it is likely to stick ooen.
Italian tuning may help.
madf
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Just managed to cure a very strange problem regarding misfires on my Zetec engined Mondeo. The misfire would only occur when the engine was at normal operating temperature it generally occurred at various engine speeds and no particular pattern was evident. The spark plugs were nearly new so the next logical step seemed to be changing the HT leads for OEM parts.
The new leads made no difference and the problem continued. I have found that after a tank of Optimax and a dosage of injector cleaner the problem has now gone. I will continue to monitor this but perhaps it was a clogged injector?
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Thank you madf and carl233 for your thoughts. I have had a go at the MAF (it looked pretty clean before I started) but no apparent cure there, so the next step is the injector cleaner. I would try Optimax but Shell garages are a bit off my route. It could be the answer as I normally fill up with Esso or Tesco 'standard'.
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Esso or Texaco petrol won't be causing this unless it was a bad batch.
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Adam
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Most likely spark plugs. If they show signs of burning at the base of the ceramic insulator (which they usually do) it's time to replace them.
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Or sticking valves. If the ignition and injectors are OK, may be worth considering whether correct oils have been used. I hear that Fords are sensitive to deposit build up if incorrect oil is used.
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I had the same slight misfire around 2000 rpm during the warm up period at light throttle openings on an N reg 1.8.
I did some reading and found that often the small silver box on the bulkhead breaks after time. This measures the difference in pressure between exhaust and inlet manifold and the signal it produces controls the egr value.
You can buy a new one from ford for less than £50 I think but the cheaper option is to block the vacuum pipe from the egr solenoid to the egr value itself. I stuck a 6mm ball bearing in it and reattached the pipe, no trouble since. Worth a try as it costs virtually nothing...
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Sticking valves is a good point these types of problems generally occur on the original Zetec version which states DOHC 16v in the silver cam cover. Revision number two versions state Zetec 16v but retain the same type of cam cover. The revised design generally has much better resilience to sticking valves than the original. An N registration vehicle could be either as from available documentation it would appear that the revised Zetec unit was made available in late 95 or early 96.
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Sorry it has taken me a while to get back to this problem.
I put some injector cleaner through the system but this didn't help.
My 1.8 is the Zetec 16v revised design, so it shouldn't have sticking valves. (I use 5W/30 oil).
Meanwhile the car has passed it's MOT with reasonable emissions. (It failed on pads and discs, they were original and had done 71k).
The symptoms were very similar to Richteo's (above) so I followed his advice and disconnected the solenoid on the bulkhead that controls the EGR valve.
This seems to have cured my problem. Now I'm wondering if it is ok to leave it like this or will damage be done to the engine? It doesn't seem to affect the performance.
Finally why was this problem only there during the warm up period?
Probably only Number Cruncher can answer these questions.
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Mine has been disconnected for the last 6k with no problems. Ford removed the system from Uk models later on as it only reduced NOx emissions (I think) which aren't tested in the UK MOT.
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Richteo, many thanks for your thoughts, I'll leave it disconnected for the time being. Percy.
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