[Diy_efi] Using GM '747 to control TCC lockup only

Milosz Kardasinski miloszk
Mon Sep 11 22:16:43 UTC 2006


What I have seen in some applications is the use of a vacuum sensor
connected to ported vacuum. You'd have
to set the switch point to whatever you feel is the appropriate vacuum
threshold...but all the sensor does is ground
out, which engages the TCC below a certain vacuum setting. Some also connect
a switch in series to turn off TCC
whenever the brake pedal is depressed.

----- Original Message -----

>
> I converted a Jeep 4.2 liter to a GM throttle body, works well. But, I'm
> thinking of purchasing a MOPAR MPI conversion which was designed for that
> engine.
>
> My dilemma is that I have a 700R4 automatic in the thing and like that the
> GM ECU ('747) controls the TCC lockup. I will lose that feature in the
Mopar
> unit.
>
> Any ideas about the feasibility of using the '747 to just control the TCC
> lockup?
>
> I think I can piggy back off most of the sensors the TCC logic uses; temp,
> speed, MAP, but I'm not sure about the throttle position. I saw a cable
> throttle position sensor which might work.
>
> What happens when the ECU isn't actually controlling the fuel anymore and
> the closed loop logic gets feedback, but isn't controlling the system?
>
> Is there a better way to automatically control the TCC and disable the
other
> processing in the GM ECU?
>
> I just hate going to a switch on the dash. It's so "unelegant".





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