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 - ecu up date

hi all
I put a thread on the problem i was haveing in janurary about my wifes 97 f not running properly well after 5 weeks it is now off to an mg dealer in melbourne as my local shop cant fix it as they dont have the test book computer and we now know it is the ecu that is at fault it is not sending the spark infomation to the coil
after checking every peace off electrices in the car.
my last question i hope on this is before it goes in on wednesday is
when they conect there computer to the car if it is the ecu that is the problem can it be reset i mean can they do like your home computer reload the programe or are they a one way unit that can only be replaced
also is there a site on mg computers that i can read so i know a bit more about them and how it workes
i hate not knowing more about the runing of the car motor
hope you can help
AR Cayzer

There's a fair bit of information scattered over the net (try looking at Dieter's home page first -, but the best things to understand the operation of ECUs is to obtain a working basic knowledge of how these systems work (if you don't know already) - Dave Walkers' book published by Haynes is extremely good, but this resource on the net is a great start...

Thereafter, to get down to the nitty gritty of MEMS, you'll need the workshop manual - available from all the usual sources ;o)
Rob Bell

Thanks Rob
Dieters site was good now i know what all the wires conect to and run
can anybody from an mg dealership workshop answer my question if the ecu can be re programed .
i sort of guess it can as it looks like you can use a second hand one is this correct
you see when the ecu is out off the my car on a test unit not the test book type they tell me all seams to work sending out info but when put back in no spark infomation being sent that is why i am off to have the car fitted up to a test book unit
thanks andrew

AR Cayzer

Regarding MEMS - you'll have either MEMS1.9 (for the 1.8 MPi) or MEMS2J (for the VVC) - neither can be "reprogrammed" in the broadest sense of the word, although specific settings can be altered using the Rover diagnostic tool, Testbook.

If you replace the ECU, then either a new or second hand unit can be used and then be programmed to match the Lucas 5AS immobiliser unit.

Question is - are you sure that it is the MEMS that is at fault, and not the relay pack underneath the engine management unit?
Rob Bell

what is a relay pack i havent heard that one
what does that do does it give the spark becauce i know that is the problem
AR Cayzer

Yes - the coil pack is switched through this - and show the relevant bits of the wiring diagram...
Rob Bell

It's the main relay including 4 coils for ignition, fuel pump, oxygen sensor and starter.
Check with help of the wiring diagrams.
(Notice other links for wire color code also)

This relay (pack) is located under the black bracket with attached alloy box (ECU). Engine bay LH side.

ooops, apology. Been to slow :)

Rob Bell

well last up date i hope
I thought i better put this in so if anybody is looking in the archives they can see what i had done
as you can see by the start of this thread the trouble we had with the car.
now how it has been fixed
they put the car on the test book computer and could not fault the ecu but after about an hour they got a second hand unit from a 97 mgf and they did reprogram it to my car spec put it in and it started straight away
so this now answered many of my quetions
1/ can your old ecu be reprogramed / no
2/ can you get a secondhand ecu and have it reprogramed /yes
3/ are the numbers on the ecu the same/ no
4/ does it look the same /yes
5/ did he need to have the car/yes
6/ or can it be done just with the new and old ecu out off the car /no
7/ how long did it take to reprograme it about 10min
8/ how much will it cost i gave them the car at 0830 and got it back at 1100 it took them the time to look for other problems first remember they could not fault the ecu $220 australian about 100 pounds
yes i am or should i say my wife is back on the road after about 7 weeks off the road
AR Cayzer

This thread was discussed between 23/03/2007 and 28/03/2007

MG MGF Technical index

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