Programmable ECU for 4A_GE

jon hanson redelec at hot.co.za
Fri Nov 22 08:55:28 GMT 1996


snip
>The reason I ask is, that I have a GEMS unit mounted in a AE86 with a 4A_GE
>engine, but I can get the engine to idle when it is hot and if I touch the
>throttle, then the engine stops.
>Any good ides ?
>
>Best Regards
>Rene Pedersen
>74714.701 at CompuServe.Com
>
>
 
Thanks to Mazda and Tom for the sound advice, I new something was out of
kilter. At least now I know what sort of things to investigate once 
my wallet has recovered from the shock of buying some dyno time.

Hi Andrew, the system is a MIC (Micro Injection Controller) from a Johannesburg
based company Digital Data Systems. Their phone no is 011 793 1151 ask for
Klaus or Peter and mention that your interested in the MIC (there main business
is actually UPS's).

Hi Rene , The car is USA spec LHD 1985 Toyota MR2 MkI. The original system
was the Toyota Computer Control System (TCCS) which I suspect is a 
NipponDenso licensed version of Jetronic.
The car used a flap type air flow meter but this has been discarded
the EGR kit has been removed and blanked off, O2 sensor as well.
I still use the std throttle body and inlet manifold but the TVIS flaps
have been removed ( I didn't want to do this as the engine is lazy enough
at low revs in std form but I had no way of controlling them)

Mic is a sort of hybrid system, I've never read of anything like it
It is essentially a Throttle posn (Alpha-N) based system. ie in the main fuel
map the rows are RPM and the columns are Throttle posn's for Load.
However it also has a map Sensor which is connected to the Plenum chamber
near the throttle body. The Map readings are used to modify the fuel curve
There is a small table where you associate Map readings with a Map fuel factor
which is used in calculating injector open times.
The map sensor is also used to give ignition advance/retard based on load.
ie you have a base advance curve table based on engine rpm
this is modified by a table which has advance/retard based on the Map reading.
ie NO true three dimensional spark mapping.
As far as idling goes, I have learnt some tricks but they might not apply
to the GEMS system. are you saying that when idling with a hot engine and you
touch the throttle the engine dies. What happens when the engine is still
Warming up. In the MIC it is very important that even a very small throttle
movement from idle posn will move the fuelling from col 0(idle) to column 1
where there is quite a sharp increase in fuelling to take up the initial load
Let me know how gems works and maybe I can help
I'd be interested in comparing ign advance figures with you

Regards Jon Hanson
Johannesburg 
South Africa.




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