A buddy of mine is selling me an 85 tpi setup for dirt cheap. I know 85 was a bad year for tpi, but I have a few questions. In an old post I found someone mention that midway through the 1985 production run, GM switched over to the setup they used in 86. From what I understand, the difference is a different MAF sensor and the 165 ECM instead of the 85's 870 ECM. Is the harness the same from 85 to 86? Is a speed density harness different from the 86 version harness?

Basically, my main question is whether or not I will have problems getting things to work after the swap (i.e. 85 had mechanical speedo, and my 92 has a vss, which I believe is controlled by the 746 ECM but not by the 870). Are there any other computer controlled functions that would be a problem with the 870 ECM? If there is, should I sell the 85 ECM and harness and be able to use the tpi unit with a 730 ECM and a speed density harness?

 

If you leave your old harness in there your gauges will still work you might have to disable vats but other than that it shouldnt be a problem. Also in 85 the tpi only came with an auto if im not mistaken so thats somthing to look into.

It is much easyer to get a setup for closer to your cars year like like to find a 91-92 tpi setup harness sensors and all.