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Changing the ECU is there complications involved? watch

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    The machanic reckons everything with my dads car is fine despite the 20mpg problem. He things the ECU needs changing.

    As far as I can tell the ECU just plugs in like a cartridge and is really easy to fix, so if I replaced it what problems may I have?

    I am worried by replacing it the car will simply refuse to start etc.
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    Immobiliser? It's quite an old car, so you may not have any problems - but with newer cars, you may have problems like key transponder match, mileage not matching between the ECU and clocks, and even more problems with 2005 or later CANBUS systems where near everything in the car can be linked to the ECU.
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    AT - if an ECU needs replacing, you should generally see other faults with your car; not just the 20mpg problem. Other faults could relate to timing, exhaust etc.

    In regards to the ECU replacement - I don't know what car you have (rover??) - anyways - under the bonnet, near the footwell, near the door (anywhere) is where it could be. Some ECU's just have a wire either side for connection, but some have like a parallel port style connection which simply slots in.

    If you do replace it, make sure you reset it first. In fact, thats what I'd be doing now; check for loose connection, reset it and then try again.
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    Is the mechanic suggesting that just because he's run out of other ideas? I don't think ECUs tend to go wrong much. It might be worth resetting the ECU - disconnecting the battery will do that - if it really is an ECU problem.
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    How old is the car ?

    If it's new then most things will be linked in to it.
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    It is an N reg Ford Escort 1.6 Zetec and yes the ECU is located near the passanger footwell.

    It is an old car but a modern engine so to speak. Everything is connected to it including the imbosliser, thermostat etc.

    It is really starting to become annoying, so many different people have looked at it and none of them can spot it. Water is driping from the exhaust as well.

    It is not using any more oil or water than any car would. It is clearly not an engine fault.

    I just feel like taking out what I think is the thermostat myself
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    ECU Reset:

    - Disconnect Battery for about 10 minutes (approx)
    - Reconnect the battery
    - (Not strictly true - but normally the case) Turn ignition to second click and wait 10 secs
    - Start car
    - Turn fan to max, lights on and any other electricals items that you have. This way, any dumped stuff by the ECU reset can start reprogramming.
    - Allow engine to idle until warm and fans cut in
    - Take car out for a spin (sensible) so that ECU gets to know fuel consumption etc. This only needs to be done for half hour.

    This might not be the case for your car, but turning the ignition back and forth normally resets it properly.

    Edit: What harm can it do, doing a reset? If problems still persist, then think about the ECU replacement.
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    (Original post by walshie)
    ECU Reset:

    - Disconnect Battery for about 10 minutes (approx)
    - Reconnect the battery
    - (Not strictly true - but normally the case) Turn ignition to second click and wait 10 secs
    - Start car
    - Turn fan to max, lights on and any other electricals items that you have. This way, any dumped stuff by the ECU reset can start reprogramming.
    - Allow engine to idle until warm and fans cut in
    - Take car out for a spin (sensible) so that ECU gets to know fuel consumption etc. This only needs to be done for half hour.

    This might not be the case for your car, but turning the ignition back and forth normally resets it properly.

    Edit: What harm can it do, doing a reset? If problems still persist, then think about the ECU replacement.
    Personally I would never assume an ECU fault unless it was very obvious, ECUs are very reliable and don't go wrong 'slightly', they go wrong catastrophically, in general of course.

    I would - as Walshie has said - try resetting the ECU, although I would suggest leaving the car unplugged for 30 minutes plus, the alogorithm above is likely to be car specific, I have little idea about Ford's systems. After a reset, you will notice that the engine has to relearn slightly how to work.

    I would certainly look elsewhere in terms of poor economy, not the ECU. Have you checked the spark plugs, if so, describe the condition, it might show that it is running rich, it might show poor ignition etc. etc.

    When you start the engine and let it idle for a while and don't move it, is there a strong smell of petrol?
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    (Original post by AT82)

    It is really starting to become annoying, so many different people have looked at it and none of them can spot it. Water is driping from the exhaust as well.
    Water dripping out of the exhaust is perfectly normal. It is no way coolant (it woud instantly evaporate, exhaust gases are ~1000C!), it is simply condensation where the exhaust gets cold quickly.

    20mpg...tyre pressures? How heavy is your right foot!?

    Graham
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    (Original post by gbduo)
    Water dripping out of the exhaust is perfectly normal. It is no way coolant (it woud instantly evaporate, exhaust gases are ~1000C!), it is simply condensation where the exhaust gets cold quickly.

    20mpg...tyre pressures? How heavy is your right foot!?

    Graham
    Is normal, but an ECU could so easily cure all these problems.
    Bare in mind the car is old so 20mpg might be looking realistic soon!

    AT - as Photjabhsbj said :p: (can't spell it), it was car specific. But something like that does tend to be the case on most cars
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    Just checked the tyres and the two front ones need alot of air. It could well be that

    However there is strong smell of fuel when the car moves, i.e if my dad drops me off me off I can smell the petrol when he pulls out.

    The car is old but I the compression tests show the engine is as good as new, the engine sounds new, it runs and starts like a new car which suggest it is ECU related, however I think it is more to with a faulty ECU sender.

    I was having this conversation with my mate tonight and he reckons it is about time we enroleld on a machnaics couse to stop all this crap. I seem to know about car electrics than most machananics Although I admit I don't know how to use a spanner hence not being able to fix them
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    Does it hunt at all? On my 306 it was drinking a lot of fuel, hunting, smelling of petrol and running very rich. Turned out to be the MAP sensor hose had become disconnected, reconnected and it ran sweet as a nut! Another possibility could be the carbon canister purge valve - this was something my uncle suggested to me when I mentioned the petrol smell. It absorbs petrol fumes evaporating when the car is standing then releases them back when the engine's running, but apparently problems can be caused when the valve to purge it is blocked or malfunctioning.
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    As others have said ECUs tend to be very reliable. Only heard of them being faulty when they have been wired incorrectly or someone messed up jump starting the car. IMHO it is far more likely to be a sensor fault or the thermostat as you say. I have no experience of fords at all, but it is possible the ECU will need to be coded to the immbiliser. I have a vw polo the same age as your escort and that is definately matched to the immoboliser, so that kind of system was around at the time.

    It sounds as though the garage are just going to replace things almost at random until the fault goes away. No one seems to bother doing fault finding/testing anymore, they just replace bits and hand you the bill. Mechanics course is a good idea, and a haynes manual if you dont already have one. Get the multimeter out and test things like coolant temp sensor, lambda sensor etc. You can get an idea of how the thermostat is working by watching the temp gauge as you drive. Once warmed up the needle should barely move as the thermostat keeps the temp constant. If in doubt you could replace the thermostat regardless - its pretty cheap and replacing the coolant wont hurt either (should be done every 2yrs anyway). Don't be afraid to have a go at things - a lot of garages arent that knowledgeable anyway and take much less care than you would working on your own car. DIY fault finding can be tedious/frustrating, but your wallet will feel the benefit
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    If there's no other symptoms like hunting for revs, or difficulty in hot or cold starting, then I doubt an ECU fault...it could be a hundred things though. If you're a member of a Ford forum, see if there's anyone on it that has an Escort and is willing to let you swap the ECU with their known good one so you can make sure it is definitely an ECU fault. If there's any Ford specialists nearby then they may have an old ECU lying about you can try? If worse comes to worse any you do need a new ECU, look about for a reconditioned one as they're often much cheaper.
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    The temp guage dosn't work at all, I think this connected to the fuel problem, also some times it does hunt at idle some times it dosn't, this was fixed 3 months ago when they cleaned the idle valve but I noticed it stareted to hunt a little today.

    The problem is I know how to test all the sensors, I know what reading they should read under different circumstances but I have no idea how to locate the parts of take them apart.

    I have a Haynes manual but it is useless as there a millions of different types of escort engines so it is stupidly vague.

    I am not sure what the thermostat looks like, but there is a plug on the manifold near the main engine block which seems to be connected to the ECU, the lamda sensor is located underneath.

    I should also point out that the car passed the emisions test for the MOT with the fual fault, so a failed lamba sensor is unlikely.

    My gut feeling is now the thermostat because the temp gauge is not working. The two things must be connected.

    The problem is my dad just dosn't believe a word I say
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    Quick google turns these up -

    http://img.photobucket.com/albums/v6...emp_Sensor.jpg

    http://img.photobucket.com/albums/v6...at_Housing.jpg

    The sensors are different to the standard zetec ones (i think both the zetec ones will be 2 wire type) but the thermostat housing should be roughly similar. It looks like the the sensor which screws into the top of the housing is for the ECU, and the one that screws in at the bottom is for the temp gauge.

    To get the thermostat out you just need to remove the 3 bolts holding the large diameter outlet that points towards the front of the car. You dont need to take off the whole black plastic assembly. The bit you're after inside should look a bit like this -

    http://www.newedgeperformance.com/Pr...s/Dcp01637.jpg
 
 
 
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