dharrison

iTrader: (3)

i am installing a 350 with a highly modified TPI in my 68 chevy truck. i am using the 730 ecm. it will have an estamated 400HP. i decided to go with a strong 350th tranny since it is stonger than the 700r4. when i get the prom burned i will have to delete VSS and TCC. or use the 350 to 700r4 tailhousing adapter kit to keep VSS. unless some one makes a VSS for the 350th. i was told by one person who burns proms that it was not safe to delete VSS? i can't remember his reason, something about deceleration stalling i think? how will deleting VSS and TCC effect performance?

8Mike9

I'd try the DIY_PROM forum, unsure about decel issues with VSS disabled. TCC lockup is a no worry though, with or without it...

Vader

VSS input is used as a variable in several functions of the ECM, including:

Electric fan operation (several variable settings);
Knock sensor enable;
Decel Fuel Cut Off control;
TCC (several variable settings);
Highway Fuel and Spark Modes (several variable settings);
Shift light control for all gears (several variable settings);
TPS hysteresis settings for all four gears (several variable settings) ;
Terminal fuel cutoff and enable;
Idle spark advance enable;
And probably others I'm overlooking.

There are probably 50 or more places that a VSS setting affects the operation of another device, fuel offset, or ECM output (like TCC and EGR).

dharrison

iTrader: (3)

Thanks, i know i need VSS now. what about TCC?

8Mike9

Your TH350 most likely does not have lockup function, so just removing the wire from the harness is all that would be needed. The signal to lock the TCC would still be present at the ECM output pin, but it'll just sit there.