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MG MGF Technical - melted ignition coil

Hi,

some people could have read about this because I have written ealier on X-Power forum.
Anyway I am looking for some sugestion what could caused this or it was only because ignition coil failed.

First time it started to happen in December, when I was gently accelerating I was able to fell kind of choke (the way like fuel is suddenly cut off or you are accelerating then suddenly take back your leg from pedal and then put it back again). It happened 2 times in week so I thought nothing to worry about and forgot about it.
Next in January it happened again but this time once per 8 miles ride to my home and next week again nothing.
and finally last week on my way home the car started choking in the same way so I decided to watch what finally happen. ealier when I felt choke I took back my leg from pedal but this time I hold it.
and something happened so I stopped the car, turned off, then turned on and car was running on less then 4 cylinders. When I tried to ride the engine lamp started flashing so I decided not to go futher.
When I was waiting for help I have smelt buring plastic but I couldn't see nothing. When I reached home I was able to remove engine cover and saw one ignition coil melted.
I have already ordered 2 brand new ignition coils (someone adviced me to change both because it offen happens that after few weeks the second one could fail)
and have hope that till the end of the week they will arrive.
My question is as it is on the top of thread - what was the reason that igniotion coil has melted - it was because of failed coil or something else has broken and as a result coil has melted.

The car is MGF Trophy 160 so ignition coil is different one and has run 28 750 miles.
marius

I would guess there was a partial short circuit in the coil's primary - causing it to draw too much current.
The other possibiity is that the ECU continually drives the coil - it fails to switch off to produce the spark.

If it's the 1st case (too much current) then you need to examine the LT wiring to the coil - in case this too has been damaged by excess current. It's possible also that the output transistors in the ECU could be damaged by this current (but unlikely, since they appear to be working still).

I'd change the coils and monitor the problem closely; if the problem re-appears then get an auto-electrician to check the LT drive to the coils.

Of course, the coil could just be badly made and failed under normal operating conditions. Measuring its current resistance may provide some clues.
Steve

Hi,

I had something very similar to this with exactly the same syptoms. I Brown and Gammons first swapped the rotor arm which was badly worn / damaged. However after a few miles the symptoms re-appeared so they took it back and fonnd the new arm was badly burnt too. Apparently a non-rover distributor cap was causing the problem. - 500 miles later theres no hint of a problem.
Philip M

Hi,

thanks for comments,
today new ignition coils finally arrived by post and I was manage to fit them. I have started the car, it is working normally but the amber "engine" light is still on.
I don't know what to do because nearest Rover dealer with T4 is about 5 miles away.
Can I drive the car to them not risking nothing?
marius

and one more thing - correct me if I am wrong - VVC engine doesn't have rotor arm and distributor cap
marius

Hi Mariusz,

no mechanical distributor, of course.
However, you know I've not much sense about MEMS 3.

Things I would check:
ECU connectors
Harness to Lambda Sensors and other sensors _near_ the ignition coils. May be anything unwanted hapened while the ignition coil change ?

At last it will not hurt to disconnect the battery and leave the car powerless for half an hour. Then reconnect and see whether anything got reset.

I'm sorry, not much help.

Best
Dieter
Dieter K.

Thanks Dieter,

Today I have talked with two persons - both of them are mechanics but first one specialized in servicing rally cars (but never repaired MG) - his opinion was that error is in memory of ECU and it is not dangerous to drive a car.
Second mechanic from Rover dealer suggest me two possibilities before I connect T4 (probably on Tuesday). First one is disconnect battery, put he keys in starter to position II and next connect plus Minus cables together - this should erase memory but not sure if it help.
Second possibility is the reason why this has happened - he suggested that it can be something wrong with fuel pump and the pressure it gave.
marius

This thread was discussed between 27/01/2005 and 29/01/2005

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