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MG MGF Technical - MEMS........How adaptive?

Whilst looking through the archives I noticed someone suggest the the MGF MEMS unit can not only adapt to power output changes of the engine through modification (ie induction systems and other 'small' mods). But that it can also adapt to the individual drivers driving style; like if you are a fast aggressive driver as opposed to a gentle cruiser.

How much if any of this is correct? Can or Should the MEMS be reset after any power tweaking mods are performed?

Nigel Kidd

MEMS is indeed adaptive in terms of fine fuel and ignition control, this to enable the engine to remain emission compliant for 100,000 plus miles.

Adaptation to engine mods is a more basic aspect where up to a point changes in the amount of air flowing into the engine and the throttle positions can allow for a correction of the fuel and ignition values. It therfore compensates for the more efficient engine. My 35% plus power gain on a completely standard MEMS 1.9 and fuel economy and emissions within the original range seen before tuning is just one confirmation.

Roger Parker

...BTW be very, very careful if you consider cam changes. If there is one aspect that messes up engine management control it is a cam change.

Roger Parker

Hi all,

just a further comment on what Rog have said - donīt expect immediatly response after doing a modification. It will take a few starts and stops of the whole system as well as some driving time before the system fully adapts to the new situation. I have found this on my VVC on several alterations. The add-on airscope was indeed one that needed some time untill the full potential was given !

Regards , Carl.

when i first changed the F's (1.8i) standard air filter with K&N, i have to admit that i didn't feel any difference when driving the car, let it be gently or flooring it. the induction sound do increase but thats it. mpg remains the same.

then on surfing the k&n site, they do mention that some cars may require resetting the engine's computer to get full benefit & to avoid the fuel mixture from being too lean due to more air going into the engine(sorry, non-techie terms). its just a simple matter of unplugging the battery terminals for 15 minutes or more, re-connect, then start the engine. the mems will 'read' current signals from sensors & tune the engine accordingly. its after doing this do i feel a much more responsive acceleration & an even better mpg.


Thanks guys, can anyone confirm for sure what Jason has just said?

I'll probably try it anyway to see if my performance improves (haven't disconnected battery since fitting K&N), Its just a pain I'll have to re-tune my Stereo! :)
Nigel Kidd

I just fitted a daytona exhast and didn't notice much differnce, but after 2 days of long blasts it now goes much better, just change up to 5th at 95 (when i looked!) with a long way left to go (scary i know)! the same adaptation to the k&n was noticable.

Hi Nigel,

there is nothing gained by disconnecting the battery. The memory is of the "non-violate" -type. See it as a whiteboard where only new writing erases the old.....The memory has no power-backup and will hence not empty itself when the main battery is disconnected. So the new setting will take some time to bed in. IMO this makes it a bit difficult to judge an alteration made such as a new exthaust system or cool air to the airfilter etc.

Regards , Carl.

me still wonders how this adaption works.

There is a latch for the throttle position sensor (Reset by kicking the accelerator 5 times with ignition on)
But how in heaven works it else ?
EEPROM of course, but with a kind of 'batch store' filled from 'below' and moving away the curent applicable data on top?

Can I help with looking up the IC parts types in my broken ECU ?

Dieter Koennecke

EEPROM and FLASH would be the obvious answers, but they only have a limited life (20 000 writes I think) which you would get thru quite rapidly - certainly faster than 10 years.
It is more lightly to use SRAM- which doesn't need clocking, but does need power.
It could have some large caps which would alow the CPU to back up the SRAM to FLASH - but your guess is as good as mine.

BTW pumping the accelerator - igition on, with or without engine running?

Will Munns

ignition on engine off.

Roger Parker


see yourself at
I assume the design was done before the FLASH got founded. ;)
One huge ASIC only.
Dieter Koennecke

off course I don't know anything about it to have a serious word with you guys, but I think the following has something to do with tha adaptive character of the MEMS.

I notice that the engine isn't running smooth when parking in a heated garage just after been driving in the cold, on high/freeways rather sporty. Like the engine doesn't know yet that the feed of fresh cold air is stopped (by entering a garage and moving much slower). A phenomenon I 'blame' the MEMS for.


I can vouch for the MEMS being very adaptive!

I keep my *F* in a heated and very dry garage, the other day it was bitterly cold and rather damp and when I got the *F* out its 'home' it said 'Sod you' drove itself back into the garage shut the door and went into a sulk and refused to start again!

Ted Newman

Guys this is technical subject and not flame wars

I think the question from Nigel is a bit confusing due to 'what means adaptive'

Of course is MEMS adaptive in relation to all the attached sensors and internal fixed timings. Controllers and regulators with digital and as well analogue inputs.

But its not adaptive in the way of a 'fuzzy logic' would be.

PS. ECU is stupid like a MEGA. Himmel, Ar*ch und Zwirn !! :)
Dieter Koennecke

Sorry, I don't understand what plunging the throttle 5 times with the ignition on resets a stepper motor?

Why would you want to do this? What are the advantages of doing this?

(Ahhhh-memories of special cheats on old console games "Pres up, down, left, right, A + Start button on title screen for special features!)
N Kidd

Hi all,
yes, if done the right way it resets the stepper motor. On occasion when the engine is a bit hard to start (damp) one tend to fiddle with the accelerator during startup. This can be mistaken by the MEMS and alter the initial number of steps for the valve. Also when the system closes down after a trip the stepper motor can be interrupted in any way and hence be out of sync upon next startup.
A typical situation : When mounting the K&N / Pipercross for the first time and starting the engine there is a slight hesitation. The stepper motor value doesnīt correspond to the amount of less restricted air and some confusion is in the MEMS ! This will settle until the next start and new number of steps will be recorded. This is also valid for change to the Thropy / Vauxhall / Opel throttle body...

Regards , Carl.

This thread was discussed between 15/01/2002 and 22/01/2002

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