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Old 11-22-2010, 05:22 PM   #50
I've Been Resigned
johnjen's Avatar
Joined: Nov 2001
Location: Seattle
Oddometer: 16,090
Originally Posted by Poolside

You bet. Not so pie-in-the-sky as you might think. You can get virtually the whole way there with external mods.

And for a hell of a lot less time and money spent on getting it working in the first place, let alone the time spent dialing it in, from scratch.

That 16 year old Motronic was born in the 80's. The version in the 1100/1150 is called a Mono Motronic It was designed for throttle body (single injection point) fuel injection systems. It was re-labeled simply Motronic as the OE product for the BMW boxer motor.

It along with most (if not all) of the early EFI systems were single channel or 'simplified' systems. Mostly because of the limitations of the available technology back then. My Volvo 164 had 3 paired injectors so even though it was a 6 cylinder engine it only 'knew' about 3 cylinders, sorta, kinda.

Because of the 180 opposed cylinder arrangement on the boxer motor, the Mono Motronic ECU can be operated as if it's controlling a single cylinder motor running at twice the RPM.

The primary problem with the Mono Jetronic is that BMW used it to control 2 injectors with a single injector signal. The method is commonly referred to as batch injection. It is sort of like wasted spark ignition, only for fuel.

That's ok for spark control, but it leaves a lot to be desired from a fuel control point of view.

Another 'limitation' is the overall 'resolution' of the early EFI systems. Sensor inputs and processing power were crude by todays standards. So getting the older systems to step up and effectively deal with todays emission standards required 'creative' solutions. Translated into BMW speak they are called 'driveability issues'.

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