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MG MGF Technical - Big Power loss Problem HELP!!

Have a 1996 1.8 non vvc mgf. Has covered 67K miles now and has developed a problem. I have just aquired it and know that it was fine until recently as i know its history.
When it warms up intermittantly the power really cuts back on you and makes you severley kangaroo it as the power cuts in and out. Turn the key off and on again and it seems as though it resolves it for a while.
Since then the timing belt tensioner has fell apart and done all the valves liners and 2 pistons.
I have not put a new engine in and there is still this problem. Thought it may be the CAT but there is a DECAT in place so its not that. I have changed the lambda sensor and its not that. Also it appears to be heating up to quickly and idles very lumpy now aswell. IT seems almost as if its only running on 3 cylinders or the timing is out or its really rich as you can smell rich fuel and black smoke sometimes comes out along with bad fuel consumption.
Any ideas? Rover had no ideas without booking it in and trying another ecu and various other things.
Please help.
A1Syd

Sounds like ECU
but it could be just the crank sensor!!

I think you have no alternative but to take it in and let them put sensors on it etc...
Crank sensor is about £40 for the part and they go wrong when the engine is hot and stop the engine firing over about 3500 revs

Take it in mate
it wont hurt

Neil

I agree with Neil - certainly sounds like a fuelling/ignition fault. Crank sensor has got to be a suspect - but also when was the distributer last serviced with a new head and rotor arm?
Rob Bell

Good point

start at the cheap end!
Neil

I had to call the AA out (the shame of it!) before I realised my problem was my crank sensor, if this is the case then it will be worse at higher revs.
I had 'lost' the screw holding the sensor in, but some investigaton revealed this knocking around localy, so the AA man just head my bonnet whilst I fixed it!
Will Munns

This is a N reg so doesn't have the coil packs, does it still have a crank sensor? where is this located if so? on the gearbox or engine as i dont remember seeing it when i changed the engine.
Also yes if you put foot flat down in neutral the revs will go up to about 4K and cut up and down around here.
If i disconnect the TPS and do the same the revs bounce around 5K but i have changed the TPS so im sure its not that.
It has a brand new dizzy cap and rotor arm and leads so i don't susspect them plus i have tried another coil and this seems to be the same.
A1Syd

I have looked at the crank angle sensor and this was fine. It is on the block so was replaced when the engine was replaced as ut was on the new block. There was a small bit of metallic dust on it but not enough to affect it.
Tried it again today and its on and off getting worse as now sometimes it will only reach about 3K revs. am thinking it must be the ECU?
Any Ideas left??
A Sydney

This thread was discussed between 28/05/2004 and 31/05/2004

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