New to the list...

TVS TKMVS at clara.net
Mon Jun 12 23:08:07 GMT 2000


    New to the list and could do with some advice regarding a EFI project!
  I'm in the process of fitting, and modifying, a Bosch L Jetronic EFI to a
MG Midget. I've got most of the bits including the ECU from Jaguar XJ6.

In order to recalibrate the system I'm planing on reading the analogue
output from the airflow metre with a laptop PC. The PC will then use a
lookup table for airflow and rpm to find a new value which will be converted
to analogue and sent to the ECU. I'm also going to fit a O2 sensor to ether
help me build up a map or run in  closed loop with the PC. Can anybody tell
me if I'm missing something important or got something fundamentally wrong?!

I've got a few more plans/questions:
1) The O2 sensor has 4 wires (From a Bosch Motronic I think) 2 white going
to a red plug... power? and a grey and black... out put with black ground?

2) How many times persecond should the PC be able to read the data/look up
value/output data? I was considering about > 10Hz if possible.

3) What sort of resolution should the look-up-table/map have? Again I
reckoned on 0.1V from the airflow metre (2.5V to 7.5V I think) and 50rpm.
RPM range from 500-7500rpm so giving me around 7000 values in a 140/50
table?

4) If I have sufficient processor time left mapped ignition would be nice...
but I'm running out of ports on a laptop! (only one parallel port)

5) Oh, and perhaps most important... the ECU fires the injectors every 3rd
ignition pulse as it from a 6 cylnd. engine. I need it to fire every 2nd.
Can I modify the 'divide by 3' bit in the ECU or should I fit a sensor in
the dizzy/on the crank to send 3 pulses per rev to it?

6) As the flap airflow metre looks like it's going to be quite a restriction
on the flow... I was wondering if I could use a hot wire meter from a JE
system. Are these self contained units? i.e. do I just supply it with power
and it gives a voltage out like a flap meter? Or does the ECU from these
systmes need to do some clever suff as well?!

All advice other than 'Don't do it!' ( I have had that in the past ;-)
gratefully received... Please excuse any spelling mistakes that make it past
the checker...Dyslexic :-(   Many thanks, Toby.

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