yes, it can be done.
one good book is the jeff hartman book. "how to tune and modify engine management systems."
the chapter 17 on the JAG-Rolet, with Bob Norwoods cars, this one on page 180. is a Chev 350 in a 1989 Jag. +L98 , + Motec + super charger 10psi. and 4L80E Tranny.
what some do is, run the old PCM in parallel, fooling it into thinking its running the show and letting it work the Speedo/odometer and tach. and warning lamps.
sure it (stock ecu) will be stuck with lots of DTCs but let it. its not doing much. (unplug the CEL)
yes, the vss adaptor are sold at summit racing.
The Tacho can run of a crank sensor on the diesel, with the correct setup. (and conversions of signal)
in Normoods car the factory PCM was removed but others , keep it.
yes, Norwood used a custom tCM called ACEL/DFI
he programed the DFI ,(my guess it's not made now)
and had to program the Motec to modulate the jag tacho, he said very hard work reverse engineering the tach. and make it happy.
yes the stock ECU , sends data to the TCM telling it, load data. so it can shift by load. (ex. later shifts up hills)
http://www.jegs.com/c/Transmission-Drive...4/10002/-1
they are not cheap.
it be fun to take a stock suzuki with 4sp and cut the TCM wire, called ECU serial, what would happen besides ECU throwing TCM errors? for comms.
page 1. pin 6
pin 4 is the stock tacho signal in to TCM and i know what it looks like. (its just the spark sig, reflected from the coil primary) 4 pulses every 720 degrees of crank rotation.
I wonder what the stock TCM would do with all others working right. all other pins but pin 6
http://www.fixkick.com/tranny/TCM/FSM-TCM-SCH.pdf
VSS2 is easy the tranny tail shaft sensor is still there. pins 2 and 3
Vss1 in the speedo is just a backup for vss1 failures.
im not sure how the jetta tacho works, some are digital >analog needle, others are analog to analog. (in that they average the number of analog spark hits to a gauge.
newer years the PCM sends a voltage to voltmeter tacho. bam easy.
the suzuki is pure analog tach.
wow, 38mpg, nice rig.... real nice. and a fun project
i just upgraded the gallery engine. it resizes most photos , automatically.
what size you got, ill test it.
file size and pixel H &Width.?
4 my guess is lockup will not happen unless the serial line talks right. its a load and speed decision, that. so my guess is the TCC would not lock up. with serial dead.
pure speculation. on serial data...
my be you can find that custom TCM on fleabay cheap after someone gave up on it. (or upgraded, etc)
be lots of fun programming one. Im sure.
all the best to you,