Hi,
Just after some quick advice on this one, over the weekend my 2000 Citrown Saxo (no not a boy racer special!) developed a strange sort of mis fire,
I had a garage look at it today, theyve keptit overnight and they advise so for its probably the engene management system needs replacing.
Anyone have any idea how much this is likley to cost me?
Thanks in advance guys
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Firstly you have not really told us what the fault is or how often it mis fires. I would go for the ECU I'd start with plugs leads and coil. If thats all the garage can say then they are apout to rip you off. Give us more information. Regards Peter
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right ok well started maybe friday night it stalled a few times befoer it went which is a first in the 2 years ive had it and then will drive fine for 10-15 miles then suddenly loose power and then pick up again repetedly - causing bunny hops, also then when i get to a junction/lights the engine appears to rev itself up with no intervention from me - car in neutral, feet off pedals.
The AA was as helpful as they could be which wasnt really very and jsut advised em to take it to a garage, apparently its something to do with the engine management wanting to weeaken and strengthen the fuel mixtures randomly :-s
im not much of a mechanic for self diagnosis but it sounds expencinve
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sorry - tried plugs and new ht leads saturday afternoon - no different
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Very unlikely to be the ECU itself.
This is the electronic management box for ignition & fuel injection.
If they go wrong which is very rare, it is usually permenant & not an intermittent thing.
Much more likely to be an intermittent conexion to one of the many engine sensors,a faulty sensor, or possibly the knock sensor on the exhaust.
Check around all the engine sensor plugs for corrosion. Give the conexions a squirt of WD40.
If still no joy take it to a dealer who has the diagnostic equip
for this model, which if he knows how to use it should reveal the problem.
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We are still shooting in the dark a bit with this car. Can you be specific with the model of the car, engine size etc. Too many variables to begin suggesting what the problem is other than the usual wiring and earthing problems which should be first stop. Does the engine management warning light illuminate at any time? If so there will be a fault code stored on the ECU which may shed some light on the prob. Specialist kit needed to extract the codes accurately I'm afraid.
Andrew
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Simplicate and add lightness!!
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sorry, its a 1.1 Saxo 2000.
No engine warning lights just the bunny hops and over revving
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From memory this car has a single point injection system. Very common failure is the stepper motor which controls the idle speed via a plunger which incorporates a microswitch to tell the ecu when the throttle lever is in contact with it, ie when your foot is off the pedal. If, sorry, when the switch goes awol, the ecu doesnt know whether the stepper motor is in contact or not so will keep rolling the plunger out waiting for the switch to open until the engine speed signal tips it the wink that the engine is over revving whereupon the ecu will shut off the fuel to drop the speed. By now the ecu will have its knickers in a knot and will have lost the will to live let alone control the idle speed and over run fuel shut off function with the symptoms you describe. Replacement is the only option and diagnosis is simple, switch on the ignition and observe the plunger which should chunter happily out to open the throttle to the start position whereupon after starting should inch back to the idle position and gently move in and out slightly to maintain engine speed. If it just stays put then it has failed. If however it is dancing about all over the place then suspect the throttle position sensor which entails replacement of the whole throttle body.
Sorry to witter on......
Andrew
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Simplicate and add lightness!!
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If the throttle body is a Bosch unit, similar to those used on small FIATs, I understand there is a trick with a 21 watt car bulb:
connect the bulb in series with the switch, and your car battery (with the usual wiring disconnected) - open and close the switch a few times.
Job done.
The few amps surge of the cold filament is enough to re-wet the contacts in the switch.
Regards
John H.
the above in good faith - I am not a mechanic.
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