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MG MGF Technical - HELP Engine problems

Can anyone help

Car is a 1.8i with 69000 miles march 97 model.

Recently the car has been behaving quite badly where you can be cruising 70ish and you can feel the engine cut for a nano second and keep going fine.
also the when driving slowly or at idle the revs are dancing around a bit. This is happening hot or cold.

This morning for instance when started the engine revs where definatly dancing ariound and when driving the engine revs kept doing funny things like the dropping to zero and then picking up to 3500 revs, this was at a speed of 40.

Could this be the HT leads as they are the original, plugs where changed at 60000 service.

If not what could be the problem as no engine warning light is coming on.

Tom
Tom Randell

Tom, this could be any number of things, try all the obvious things first like leads/diz cap etc.
Had a similar problem ,turned out to be a faulty(new) rotor arm,HTH.Mike.
mike

The ignition leads and the distribution cap are the first things that come to my mind. I would change them anyway after 69k miles and see what happens.

Spyros
Spyros Papageorghiou

Tom,

How come the revs could drop to zero when at 40mph? If you were in gear with the clutch in then that would be mechanically impossible. If however, the indicated revs dropped to zero then it would suggest a problem with the ignition or the electrical supply to ignition. After checking the above suggestions by Mike first try connecting a wire from the brown/pink on the purge valve at the front of the engine through a 12volt bulb to earth. Arrange it so you can observe the bulb while driving. If it flickers off when you detect the problem then it will be an electrical supply problem. Check also security of Fuses 1 and 2 under the bonnet.
PS Some people use the brown/pink wire connection on the purge valve for the window delay circuit mod, so you may already have a connection from this to the front of the car.

HTH

Bruce
Bruce Caldwell

Bruce is right, if the tacho falls to zero at 40mph in gear then it is not receiving its rpm signal. I am not sure about the F but this typically comes from the electronic ignition. When it happened to me (on a Ford) it was caused by corrosion in the distributor.
Brian

I have on order new leads, dist cap and rotor arm. So will try these first.

The other think I have been told maybe coil coorroded.
I will try the obvious and easy things first.
I must admit the revs did fall me as I know if the car is moving and car in gear the revs should stay constant.

Tom
Tom Randell

TRY THE CRANK SENSOR AND THE ASSOCIATED CONNECTION
JOE

More problems.

Engine takes a long time to start and exhaust has suddenly gone rather black i assume due to the rough running and unburnt fuel.

Does anyone know if the engine management records problems even if the warning light is not coming on showing a problem.

Tom
Tom Randell

Tom,

ECU will record problems without displaying warning light.

Try phoning 01926 632066 and speak to Marvin, Mike or Roy. That should cure it.

Good luck.

Paul
P9 VLS
Paul

Cheers for that idea Paul, spoke to Marvin yesterday and suggested I do the HT lead etc first.

Have spoken to dealer and they said change HT etc before seeing them to check for other faults.

Looks like it is a waiting game fit new parts and hope it cures if not dealer problem and hopefully warranty direct will cover most the cost.

Tom
Tom Randell

Tom,

Lots of things to check first of course, but a friend of mine with an N reg MPi recently had to have his ECU changed. The symptoms were simply that the engine cut out every now and then, no coughing or spluttering, just suddenly no fuel supply. In investigation a frayed petrol pump cable was found, but this didn't fix it. Replacing the ECU did. Now, I know this doesn't match your symptoms, but thought you might want to stack this away as a last resort option. It seems that replacement ECUs vary in price dependent on VIN. Some are exchange items and are therefore cheaper. My friend's was exchangeable and the cost was something like £250 including the MGR dealer testbook session to reprogram. HTH

Dave
Dave

This thread was discussed between 15/05/2002 and 16/05/2002

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