I am converting a TBI harness to a speed density TPI harness. The TBI only had one wire for each injector running to the ecm. Where on the pin out i have lists two wires for each bank of injectors. The ones that i don't know about are the injector low drive. What exactly do these do. Do i need to run the second half of the circut back to the computer or is it just a 12 V source like on the TBI?

 

Both TBI, or TPI, injectors have 12v applied to the one side, and then the ecm grounds the other side of the injector to turn it *on*.


So use each injector lead (a total of 4 wires), from the TBI, as a *bank* for the TPI.

The TBI has 2 hot leads, and 2 ecm leads. You'll have to branch each lead of those leads into 4 endings for the port setup.

Hope that's clear.

 

ok then what pins should i use for the wires at the computer the pin out sheet i have lists
Inj 1357 as C11
inj 2468 as c-12

also in my pin out it lists Inj. drive low at D6 and D7

i have the wires from the TBI injectors running to C11 and C12 right now what would go in D6 and D7?

 

For a 730 that would be correct. The injector wires from the ECM should be put onthe C11 and C12.
The D6 & D7 are to be grounded from the ECM. Those are the ECM injector paths to ground.

 

So for the D6 & D7 I just need to run wires to a engine block ground?

 

Yep!