318ti.org forum - m50 obd1 swap, ISSUES!

Having agonizing issues with this swap. '96 318ti, bought '93 325 vert. Swapped motor, dme, and harness. Worked through a bunch of issues and now getting to one last issue, limp mode of some sort.

Motor will rev to just above 3,000 rpm and then start miss firing. Its intentional as you can pull the battery cable and reset the dme, drive the car a bit and it'll start back up. Traced all the vacuum lines, found fpr line cracked. Replaced it and all was well! Put a few miles on it, at least double the amount as previous dme resets. Shut car off thinking issue was fixed, shortly after restart and drive home it went back into limp mode. Car also seems to have a rev limit of 5,100 rpm, possibly a related issue? It has a fluctuating idle that seems to appear when the limp mode starts.

We also replaced the crank position sensor thinking that was the culprit of a previous issue, so that sensor is new. Tried a different maf for this and the idle issue with no apparent luck.

We swapped the 6 cylinder cluster into the car but the odometer is not working or lighting up. Our harness was missing the o2 plug on it, and I don't remember how it was previously hooked up. Does anyone have an idea on the color coding for the o2 and harness wires? We hooked it up the way our friend's obd1 m50 car is, or at least the way it appeared to be hooked up.

Going to try and update this as we work through the issue and to hopefully get more ideas as to what is going on.