Welcome to our resource for MG Car Information.



MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGF Technical - MGF, engine sudden stop

Returning home last night the engine of my 98 MPI suddenly went off. Many tries but she would not start. Phoned AA and when the expert arrived tried and the car happily started with a roar-shame on me-. Ten minutes later -the AA guy gone- same thing happened and again she would not start. Wait for ten minutes and the engine easily started and managed to reach home. I experienced a similar episode last week but later the car did fine. Trouble is that as I live quite far away from the city am reluctant to use the car. Any ideas?
David Cullen

Hi David,
This could be a difficult one. When waiting for a 2nd year service at my local dealer, I read a coffee table book. All it said was how complicated is was to find a result. Good luck and tell me your findings.

So, the engine turns over, the instruments, lights etc work OK - but the engine just doesn't fire ?
Two lines of thought -
1) ignition coil is breaking down
2) fuel delivery problems - but I would expect some warning of failure if this is the problem.

Can you get a dealer to run TestBook daignostics to see if any errors are logged ?

If there were instrument lights and no engine turn over
check the starter motor lead.
This happened to me a couple of weeks ago the connector gets corroded to a degree that it cannot make a decent connection I found taking it off and giving it a bit of a clean with my screwdriver worked.
My car is a 98 so it had accumulated 5 years worth of crap

Steve, this wouldn't kill the engine, only stop it restarting.
I too fear a fuel problem, also, have you toughed anything in the centre console area recently?
Will Munns

Thanks chaps. Intriguing facts are: turning the key the car starts fine as always however after a while -as Will said- something suddenly kill the engine. Kill is the right word. Every light seems to be fine and the starter turns over. Sometimes the engine start again and sometimes absolutely refuses to fire. However if I wait 15-30 minutes it would start again. Trouble is that I am 60 miles away of the nearest possible garage and TestBook diagnostic and can not really trust to get there.
David Cullen

re starting problems, perhaps check the state of your battery. I seem to recall having starting problems with my F when the battery was in the process of dying. Perhaps it does not have enough kick to make it fire, until it has rested for 15-20 mins. Mine got to the stage where it would not turn the engine over, just give a series of machine gun like clicks. As soon as it was replaced, all was well again. A six year old battery could well be on the way out. I too called the AA out a few times, only to have it leap into life as soon as they turned the key.

This would not (should not) cause the engine to die in the first place though.

Neil Courtney

The first thing to do is to buy a can of contact cleaner and go around the engine cleaning the connectors (unplug squirt both sides plug and unplug a few times.

Pay particular attention to
the crankshaft sensor - inlet side of engine, very 'rear' of engine, in line with the crank pointing at the gearbox. (black plug?)
The coolant sensor (not lightly in this case, but save you trouble later) exaust side of the engine, flywheel end again, near the top, (blue plug and brown plug)
The throttle position sensor, opposite side of the throttle to the throttle cable (black?)
The Injector wires (come out of the inlet manifold at the throttle end).
The coil(s) bolted to the engine under the inlet manifold

Then check the security of the air connections into the inlet manifold, of particular attention should be the MEMS connection, which is the small connector at the flywheel end, leading to a flame trap and then on to the MEMS unit - cheak all is secure.
Will Munns

I“ll give it a try a clean the contacts Will. Neil, the battery is quite new. I wouln“t think the problem is there. The thing is that the F run really fine perhaps for half hour or more and then stops. May it be related with temperature?. Something getting hot?
D. Cullen

>Something getting hot?

Quite probebly, but take care with assumptions - when electrical contacts get gunked up, they 'grow' carbon, which is resistive, so it consumes power, in doing so it gets hot and the resistance grows, so an item some distance from a heat source (like the connections to the fuel pump) could also give the same effects.

You didn't say if you can hear the fuel pump, the fuel pump runs for about 3 seconds when you first turn the key, and then only runs if it sees the crank turning. It sounds like an electric ariel. Turn off for a few seconds and then turn back on, you should hear it priming.
Will Munns

Yes Will, fuel pump is quite audible after turning the key.
D. Cullen

Grrr.... it happened again. As suggested I cleaned every possible contact and sensor in my F. This morning after she had been running for about 40 minutes in my entrance I became confident and decided to take her for a ride. Big mistake... After ten minutes going really fast and fine, she suddenly died and would not start. As I have become an expert now I didn“t worry, red the news, and after a long while she decided to start again to take me home. Most intriguing I must say. Facts are I would not be able to make the many miles to the nearest dealer and she is not anylonger to be trusted. David
David Cullen

David, if you think that it may be heat related, how about taking it for a low speed run instead of 'going really fast and fine'? Perhaps you can make the 60 miles running at 50mph or less.
Neil Courtney

Have you checked the rotor? A couple of weeks ago there was someone that was somewhat similar, especially when cornering, and it turned out to be a broken rotor.

Worth a try maybe?

Johan Slagter

On our 97 'F, had a very similar problem. Took it to MG, had the whole TestBook diagnosis, and they said that they couldn't find a fault. Problem was still there.

So, after reading through the archive here, I thought I'd take the plunge and change the HT leads, Rotor Arm and Distributor Cap. For an outlay of around £50m it's cheaper than the testbook - and it worked! The MG has been running sweet ever since!
J Clarke

>For an outlay of around £50m

£50m???? Genuine rover parts are a total rip off! ;-)
Will Munns

You might want to try the coolant sensor. I had this problem on my 1.8 k-series. WOuld start fine from cold but to start once its warm it wouldnt have it.

If youve got an FSE fitted it might be worth checking the fuel pressure as well. If its too high it will just flood the engine when warm.

Try pulling the connector off the coolant sensor and if it starts then you know its something to do with the sensor
mark forrester

Oh boy, I can not believe it!
As Neil suggested I managed to make it to the dealer. Sixty miles driving really slow -not quite the final few-. The F did fine. Not a single problem.
Rover people run the whole TestBook diagnosis to find... NOTHING. They said a standard maintenance service was then performed and every possible failure site was check. Wallet empty however happy I then took the way home... but at about 45 miles later she decided to went off. Again.
I am really worried now.
David Cullen

Does the F have any heat shields? I havn't looked for this in the TF, but perhaps if it does then it has slipped, and something is getting hotter than it should. Exhaust system leak? But then it would probably sound like a tractor and the dealers would have found this during the service. Hmmm.

New dealers? I guess you don't have too much choice where you are.
Neil Courtney

Testbook would have found sensor failures.
If the ECU hasn't stored any, then there wasn't any.

It's any actuator (Motor/relay/etc) if the problem reffers to an electric 'gremlin'.

Or contact problems with main relay or ECU itself.

My few pence.

Dieter K.

Considering what I have been through -and still am- I would like to buy my own F scanner so I could run a TextBook any time a problem arise. Big question: Do any of you mates know of an affordable handheld scanner?. It should be easy to use and of course not very expensive. David.
David Cullen

>It should be easy to use and of course not very expensive.

Impossible, unfortunately and half of the Rover and Land-Rover *world* is looking for one since years.

It's easier to throw the box to garbage and swap to an Emerald ECU or similar.

Dieter K.

I suffered a similar problem many years ago in My Rover SD1 nobody could find the fault until somebody suggested changing the fuel filter.

I had at some stage purchased some VERY dirty fuel and the solids that had accunulated in the filter would pack hard into the filter fabric allowing it to suck flat and virtually stop the flow of fuel. Waiting 20-30 minutes allowed the pressures to slowly equalise and I could start and run again until the sediment built up again. It might be worth checking you tank and filter to see if it is something similar, especially when all the tests run indicate that there is nothing wrong with the electrics.
Phil Stafford

Dieter please let me know about that swap to another ECU. Is it possible? Would every function adapt?
D. Cullen

Dave, you would have to go for an exactly simmiler MEMS(engine management)/5AS(immobilizer)/keyfobs, or buy a Emerald ECU(£600?). An emerald will alow you to fully control the engine, change maps, add a shift light, view all data on a standard computer etc.

You could be having wireing trouble, there have been a few people who have managed to dammage the wire that runs between the 5AS and the MEMS, usually by grounding the wire, this means that halfway thru a journey the ECU looses the 'deimmobilise' signal, so it stops the engine. Try taking footwell kick panel on the passanger side out (the one with a light in it) and wiggleing the wires to the immobilizer (bottom black box right in the middle under the radio) with the engine running. Then try the same with the wires in the engine bay.
Will Munns

Fact is that quite desperate I took the car to another not-Rover garage. They do not have TestBook available of course, however told me that is absolutely unnecessary and that they could find the failure checking the sensors with an oscilloscope (?).
Anyway, yesterday they let me know that have detected a faulty cranck-sensor and ignition coil and have to replace them. Apparently the cranck sensor is available but not quite the ignition coil. They have propossed a Lucas replacement. I have accepted but at his stage a few opinions from the people that know about would be most welcome. David.
David Cullen

Lucus probebly make the Rover one anyway- but! they may have to cut off the Rover coil connector, and this might mean that _any_ fault in the future will be attributed to the coil by MGR, I would use the lucus coil if it is plug compatible, or wait for an MGR one (very simple to change the coil from below)

The crank sensor would certainly give you the problems you are seeing, as would a faulty coil, but I'm surprised they said both. The crank sensor is a 2 minute job to replace, neither job has any bearing on the other So I would get the crank sensor done and wait for a Rover coil - unless they are plug compatible (why not give L-Suk (ok... LS-uk) a call and ask?
Will Munns

The MGF saga continues and I feel so hopeless now. Cranck sensor and ignition coil were ordered and replaced however the car would not start. Apparently there is no spark coming out from neither the sensor nor the coil. So...what now. Help please?
I am sad. This F -which I used to love- is almost unused and has spent most of her life under repair. I have other cars -Alfa and Toyota- which never experience a problem. -Very difficult to keep my national proud up-.
D. Cullen

Get mechanic to check the ECU earths and the engine earthing strap.

Is power getting to the coils (usually power is feed to the coils and they earth thru the ECU to the ECU ground)
Will Munns

I had a probalem similar to this a couple of years ago and it was in and out of the garage for 4 months and was a nightmare.

To this day I have no idea what the problem was but it cost over 2K to fix and had new engine loom, main wire loom, distributor, rotor arm, crank sensor, ecu, coil ,ht leads, spark plugs and I am sure there are parts which I was not charged for as the garage was getting stumped and did have some goodwill from MGR.

The problem was that it was intermittant and even when it went wrong in the hands of the dealer they could not dectect the problem even with a testbook plugged up.

Tom Randell@ work

Had something simular also last year. 'Sometimes something' cut of the engine a few seconds after starting it.
Garage couldn't find anything with the testbook even if it happend in the garage. Eachtime the testbook indicated that some sensor was bad but after replacing it the problem was still there. It cost a lot of money and in my opinion the sensor were not bad at all. After 2 months in and out of the garage, it turned out to be an electrical short cut of the loom from the alarm/immobiliser behind the radio (i installed the radio myself some 4years before that...).

Have you worked on or nearby any of the electrical looms yourself ? Maybe some wire was damaged...



I really thank you Chaps. I really dont know what else to do. I have passed your ideas and they are checking every connection. The engine turns all right but would not fire -not even an attemp to-. Funny thing is that I came in driving the car. The garage looks fine as I have seen how they easily fixed a Ferrari and a brand new Porsche which are long gone, however they dont know what to do with the F which is still there. David
David Cullen

What Geert suggest may be a possibility if the alarm/immobilizer has the capacity to completely block the ECU and the ignition. I wonder if any of you Chaps can illustrate me about that possibility and perhaps send a sketch of the connections between the immobilizer and the ECU. Is it possible to measure if the ECU is receiving a signal after turning the key ? -or after the alarm is off-. David
David Cullen

David, please have a look at this thread :

Same problem as Geert and similar to ours (thanks again Geert :))

Look at the pictures...

Hope this will help you !


Why not ask garage to revert to old coil and sensor and see if it starts again.

If I'm right the coil on MPI should be part number NEC100630 and costs about £46 ex vat

Suggests NEC manufacture.

May be worth researching Rover/Lucas/NEC coils via google

Good luck


ps my money is on the coil ;-)
John Thomas


I'm sorry, had no time to follow. Led to some confusion. Apology.

Pics from Benjy, from the archives regarding harness behind the radio.

MEMS 1.9 ECU pre MY2000 (not VVC!)

Diagram Alarm ECU

Picures of the Alarm ECU

Anything else required ?

I'd keep on this investigations and Will's
hints at first and turn to the next probable failure after having proved it's OK. I said already and i.e. Tom confirmed,
Testbook is a funny tool, but really useless with NONE sensor failures.
I bet it's the wiring harness or any actuator, like ignition coil.

Dieter K.

Awful sad news. Nothing wrong has been found. Every suggested possibility was explored...and nothing was found. The engine still turns but there is no ignition. I have been told that at this stage they have to take the MEMS out to be send to some other place together with the immobiliser and the key bleeper. Must say I fear the worst and at this stage believe that my F is gone. DC
David Cullen

David, no! Your F is not yet gone! Maybe it needs someone with the right touch to get ir right, but I would say that the problem is there just waiting to be found. Have you gone back to the dealers that sold you the car in the first place? Maybe they will come to the party and help you out in your hour of need?
Neil Courtney

No way. Nothing was finally found. Every possible cause of failure was investigated but the car would not start. Apparently there is no signal to the ignition coil coming out from the MEMS. Anyway, yesterday they took the MEMS off, together with the immobiliser and the blipper to be sent somewhere to be analized. From my side...hopeless. DC
David Cullen

This thread was discussed between 28/01/2004 and 24/02/2004

MG MGF Technical index

This thread is from the archive. The Live MG MGF Technical BBS is active now.