Bosch Mono-Jetronic

[Land Shark]

At 02:28 PM 2/1/96 GMT+0200, you wrote:

>No barometric pressure meter. Definitely no air mass / manifold pressure
>sensor. Except if they're using the inlet ait temp sensor (looks like a
>thermistor) but if that's the case they're _really_ good :-)

 OK then, you have what BOSCH calls the Alpha-n system .. (I wish I had a
 charachter to represent "alpha" in ISO text!) ..

 Alpha is throttle angle
 N is of course, rpm

 I am AMAZED that they actually built some cars (street) based on this,
 but SA must have different emissions laws than the US :)

 The engine is completely mapped, and ANY change to the engine AT ALL will
 require a remapping ... You'll also notice that the WEATHER has some bad
 effects on the driveability ... as the air density changes, the system can
 NOT really compensate that well ..

 What they do is derive the static manifold pressure at STP as a function of
 Alpha and N .. from that and a map of engine VE [ f(air density, rpm) ] you
 can derive the VE as a function of alpha and rpm...

 With a VE table, and a lambda table all is well ...

>Dump of the EPROM - I'm planning to do that... :-)

 Also note the processor (package, pins, xtal speed, numbers on top)!!

 Also, I have seen some DME's that have a VACUUM line running to a 
 nice little baro sensor on the PCB ... 

>Apparently the system can "learn" as well, storing stuff in RAM. But maybe
>the engine's getting a little loose by now (110000 km) and the tables are
>bottoming / topping out.

 Note that "adaptive" or BLM, or whatever can only be accurate where the 
 lambda is fixed at one .. (with a normal HEGO sensor) ... at WOT this is
 not the case, above a certain load and rpm (where HEGO feedback is off) 
 it is ALSO not the case, because most manufacturers do NOT try to seek to
 lambda=1 there!!

 Jim