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MG MGF Technical - VVC Coil Pack

I have a strange problem with my 99 VVC. It has doen 36K and last year i replaced the plugs and leads.

I have noticed lately that under very slight accelartion the car seems to judder slightly, as thought the car is missing. I gave spoken to the MG owners club and they are certain that this is due to the coil pack. I originally replaced the leads because i was having difficulty starting the car. Afer replacing the leads i have not had a problem startign since.

What is your opinion, do you think the slight juddering affect could be the coil packs.

when the car is idling i can feel a slight imbalance, in that the revs drop sligthly for a second and then pick up again.

Under normal driving conditions the car never misses a beat, only under very sligt acceleration or when idling !

Any help would be much appreciated.

Sounds more like a sensor problem, ignition you would feel more at low rpm wide throttle.

Will Munns

Hi Paul,
have You had a closer look to the ignitioncoils ? Are they rusty on the metallic core ? If so possibly weak spark due to contact between laminations in the coilcore. This can in the long run ruin the switch-transistors in the MEMS. Test-Book can test for primary winding switchtime and other useful data regarding the coils. But then of course there is a need for someone at the dealer that knows how to handle the Test-Book computer..... ;)

BR, Carl.
Carl Blom

Carl, yes, last year i did have very rusty terminals on the coils, hence the replacement of the HT leads. The car has felt fine since then, its just over the last couple of weeks things have felt not quite right.

I have also recently fitted a Mike Satur daytona exhaust, could this have any impact !


I have had a very similar problem, but it usually only in 2nd or 3rd gear, I too have replaced the HT leads, because of damp start problem, but it still comes back sometimes. But I have found by spraying water dispersers (damp start) over the tail ends of the HT leads seems to stop it, I have to re do it ever 3 or 4 week as the rain draining through the boot engine vent washes it off.


Hi all,
for those of You that has replaced (taken away) the original resonator box with a K&N or similar there is space for re-arranging the VVC ignition coilpack away from the water / saltspray under the car. Can send pictures if anyone is interested. Original length of ignition cables works with this modification and there is no way the coilpack gets wet in that location !

BR, Carl.
Carl Blom

Hi Paul,

If your coil(s) are really bad and if you're going to replace one or both, please don't throw them away.
I would like to have one.
Carl's idea isn't bad but I am planning to make a whole new mounting plate for the coils very close to the sparkplugs. Therefor I need at least one coil for measuring purposes so I don't have to do so long without the car.
So if the old coils are coming out, please give me a mail.

Carl, another simple but brilliant sollution. Arend, keep us informed of your progress. Some pictures would be nice..:-)

I don't even have an F anymore and I still can't get away from the dark side. Anyone have any ideas about turning an Escort into an MGF? Has mike got a kit? :-)

Nice one Carl.

Roger Parker

Hi all,
and when we are on the subject of re-routing cables / installing ICE etc. Be a bit wary when adding new cables close to existing routed one to the MEMS,alarm-unit, EPAS or similare. I got some funny interaction between cables when doing some experimenting before joining a trackday this summer. A consistant miss-fire around 2000-3000 revīs was present when using too long ignitioncables (non-standard!) that did run close to existing multi-coloured ones going to the sensors and MEMS ! Possibly the very strong magnetic field around the ignition cables induced "noise" on the system. As soon as I had re-routed and put spacers on the ignition-cables everything was back to normal....

BR, Carl.
Carl Blom


That's one reason why I want to place the coils at another position with shorter ignition leads (about 35-40cm max.)
In the past I've noticed similar interference from the original ignition leads when they weren't correctly on the cablesupports anymore, with as a result, every now and then the cooling fan came in, even with a cold engine. I only could stop this if I turned off the ignition and waited for a minute and then restart.

This thread was discussed between 01/11/2002 and 04/11/2002

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