I have just finished replacing the wiring harness on my '87 760 Turbo. I have had this car for about six months and it had recently started to die on me from time to time. I had been aware of the harness condition since I bought the car, and realized that I was driving on borrowed time. So, when it started to die, I suspected the harness, and sure enough, with the key in the run position, I could twist the harness, hear a couple of clicks, and if it was in the right position (50% of the time) it would fire right up and away I would go. The car ran surprisingly well considering the wiring's condition. This, however, started to be a nuisance as it happened more often, so I acquired a new looking used replacement harness.

Prior to installation, the car sat in the driveway for a few weeks, and when I went to start the car to pull it into the garage, it wouldn't start, no matter how much twisting I did. I thought perhaps that I had fried something, but hoped the harness just wasn't functioning at all anymore, and that perhaps the car would just fire up after the new one was installed.

The new harness is now in the car, and after installation I was left with only one mystery wire. A friend's '87 740 Turbo showed me that this wire (car wire, not harness wire) belonged to what I'm pretty sure is throttle positioning sensor on the throttle body. So, all wires in place, I go to fire up the car. No start.

I have dumped gas into the intake manifold and it will run very smoothly for about 3 seconds or so. I have disconnected the fuel return line, and when cranking the engine I observe what I feel is an adequate flow rate; not a trickle, a stream. I have also opened up the radio suppression relay, and when I turn the key to run, it clicks into place (but I don't know if that necessarily means that it's working). The fuel rail ground spots have been cleaned to shiny with a rotary tool.

I have another ECU on the way, but don't want to fry it if I have some other problem that would do that. Does this sound like the symptons of a bad ECU? I have seen another component on a bad wiring diagram between the radio suppression relay and the ECU. Could this be it, and what/where is that thing? Could the TPS wire cause this to happen if it is making a 100% connection?

A few notes on the car: I have read in the receipts from 1988 that it had a Turbo+ installed. Could this be a contributing factor? The car had an engine and transmission installed at the dealer in 1992, but the harness must have been the original judging by its condition. I don't think the newer engine would cause any conflicts, though.

Please help, I gotta get this car out of the garage or I'm gonna be in trouble!

Thanks for your time,

Howard