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MG MGF Technical - Replacing the MEMS

Hopefully I will be receiving a new MEMS together with the main relay pack, immobilizer and key fobs from the MGF Centre, all of them already programmed. Because of electronic problems my F has been off the road for six month now and to avoid towing to the garage I would like the parts to be replaced at home. I will appreciate instructions for the correct sequence to do that -may it be feasible-. Thanks. Mike
JM Vega-P.

MEMS is bolted to the bulkhead between boot and enginebay (bay side) relay pack is behind it.

When I pulled the 5AS from the 600 it was a right ar*e positioned in the central console under the radio, I think locked down with two 8mm bolts.

Personally I would disconnect the battery before and it wouldn't matter which order I did stuff.
Will Munns

Will, many thanks for your answer.
Another question: I received one key fob only. Any way to get the old key fobs programmed to function with the new ECU and Immo?
JM Vega-P.

You need the Testbook for that, so a trip to the dealer is needed.

Johan Slagter

Hi Mike,

nice to see you.
Please don't hesitate contacting me by email if troubles repeat with the new ECU.
Found a german workshop for MK1 ECU's friendly and reliable and had some discussions with them the other day.
Just in case ......

The back of the bracket mentioned by Will. (without harness)

And take care to re-fit ALL cable ties to brackets. Harness must run with smooth curves and no force to the ECU connector.
(site shows pics of the unbolted bracket and lower fixture of the connector harness,

Good luck.
Dieter K.

Thank you all chaps. Excellent pics Dieter, and most helpful. Saturday will be the day and will see if I can put the F back in the road. Iīll let you know. Thanks.
JM Vega-P.

The F is back. Saturday was the day and the MEMS and immobilizer -already programmed at the MGF Centre- were replaced. Easy job indeed. The car started as easily and well as before, six month ago!. Spent most of the day driving, big grin on my face. Thanks go to Victoria and the MGF Centre.
Nevertheless a bit worry about the matter of reliability. My F is quite new with only 13.000k on the clock, and that was the third ECU in a row. May that happen again?
For all your kind directions I very much thank the BBS and you all mates.
JM Vega-P.

Sounds good Mike !!

Have the previous MEMS systems been analysed, just to find the cause of this trouble ?


I agree with Erik, Mike. If there is a recurrent problem, then it is better to be forewarned than to wait for another failure. If, however, it is two faulty ECUs, then count it down to exceptional bad luck...

Anyway, good to hear that you are finally back on the road! Excellent news indeed! :o)
Rob Bell

Hi all,
nice to hear that you have the car running again !
About the number of MEMS-units at fault, could it be a overvoltage issue? Thinking of either inductive high voltages created (and not dampend due to bad ground-return)or simply a faulty voltage regulator at the alternator? The MEMS is protected internally via a zener diode - but only to a degree....
A opening up and check of one of the faulty units might reveal whatīs happening. Also cut-out of one of the outputs ( coils,fuelpump etc.) due to short-circuit to ground is a way to finally kill the otherwise sturdy output drivers....
BR, Carl.
Carl Blom

Itīs a long story. Initially the F had intermittent failures. While driving the engine died and even turning over would not start again. After ten minutes or so it would fire again. That happened many times and I believed was something related to temperature. Took it to the garage where was tested -not with the original TestBook perhaps-. Crank-sensor and ignition coil were replaced and still had the very same intermittent failure. At the end of the day reported that the car would not start at all. Then MEMS was sent to MG Rover in BA. They informed that the unit was damaged beyond repair and advised to get a replacement. MGF Centre provided the replacement but once programmed the F would start for ten to 30 seconds and then died. So I asked Victoria to please mail another unit, together with the immobilizer and key-fob, already programmed. Good outcome this time and everything seems fine now. -Actually I remain uncertain not having a clue of were the problem was-. Mike.
JM Vega-P.

it looks like the fuel pump more than the ECU...

Hi Mike,

may be it's worth shipping the other ECU including brief failure description to any new upcoming aftermarket repair shop.

One of I had an email chat recently is Incotronic (Ralph Imping)
They only do ECU repairs for out of production parts.

At last may be you can sell it repaired or keep it.

Dieter K.

>While driving the engine died and even turning over would not start again. After ten minutes or so it would fire again. That happened many times and I believed was something related to temperature.

Sounds very similar to the problem that I had with my '96 F. It was eventually fixed by an RAC man - he tightened up the fuel pump outlet, which was leaking fuel, and also found a loose wire in the MEMS plug.


This thread was discussed between 22/06/2004 and 29/06/2004

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