Motronic on a BMW motorcycle
Ian Greaves
igreaves at cix.compulink.co.uk
Wed Jan 3 19:07:07 GMT 1996
In-Reply-To: <199601011110.GAA11257 at coulomb.eng.ohio-state.edu>
Hi guys!
I've recently purchased a '93 BMW K1100RS motorcycle.
The thing runs O.K. when warm but the warming up phase is bloody
'orrible!
It always fires (starts) when cold, but then will often only run on three
until it's cleared it's throat. I have to keep the throttle slightly open
otherwise it dies instantly. All this is accompanied by clouds of hazy
unburned fuel and that rich smell, coming from the exhaust. Basically,
the machine is running well rich. (About 20mpg when running warmed up!!,
that's at least double the consumption I'd expect.) I've replaced the air
filter and spark plugs. Upon dismantling bits of the bike, I discover
that the engine management uses a MAP sensor (I thought it was hot wire!)
with vacuum tubes everywhere!! The water jacket thermistor, and the
intake air thermistor measure about 4 K Ohms at ambient temp. (say 10
degrees C, not unreasonable?) I can't find any obvious vacuum leaks in
the piping, and I've opened/remade all the plug in connectors around the
place. Any Ideas, anyone, before I admit defeat and go back to the dealer
and his analyser!!
In fact, does anyone know anything about this particular Motronic system.
How does one read any fault codes? I see a three terminal connecter, I
suppose this would be a serial port. Is it clocked, or does data just
fall out of it asynchronously? What's the baud rate, levels etc.
Also any basic set up data? (Throttle pot voltage at idle, etc.)
If anyone knows anything, let me know. a) I'd love to learn all about
this version of Motronic, as it's not covered in any of my books. (only
K,L and LH in the book!) and b) I might just fix my bike!!
yours Ian Greaves, in London U.K.
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