I'm planning to do a TPI swap on my car, and I've already gathered most of the parts I need. I have an 870 ECM and harness from an 85 IROC which I will most likely sell. I plan to go with a 730 ECM and a SD harness, but I was curious as to whether or not I can use the 165 and have a functioning speedometer. I believe all the tpi cars that came with either an 870 or a 165 ECM had a cable driven speedo....correct? Would I still have issues with the 730 ECM?

 

A 730 swap should be fine with what you have now. Just run the VSS wires directly to the ECM instead of the VSS buffer that RS's used.

For a 165 you'd keeop the VSS buffer, not 100% on this off the top of my head but i'm pretty sure the earlier ECMs use a 2000ppm signal instead of 4000. A divide by 2 circuit is easy enough though. You'd want to search to verify details on this though.

 

So basically I just need to remove the vss buffer and run the wiring straight to the ECM if I go with a 730. That sounds easy enough.

I assume the vss buffer is under the dash somewhere, right? What does it look like?

 

the vssb is behind the cluster and should be about 2.5 inches long and should have three wires coming out of it. i have the same problem but im going to change out the tail shaft.and make it cable.