I got my '84 Z31-powered '88 Pathfinder up and running, and it runs like a raped ape except when cold and at idle. If I plug in the TPS (I've tried 4 others), it will idle smoothly but not rev above 2500. If I unplug it, it idles like ass at around 4-500 and sputters and pops and blows clouds of black smoke out the tail pipe but revs freely and responsively when warmed up, as well as the black soot clearing up once it's revved. From my understanding, pins 18 and 25 at the computer are for the TPS sensor, yet the wiring diagram I have labels it as the "throttle valve switch" and only measures idle, mid, and full throttle. The diagram I have only shows two wires coming from the sensor as blue/green and pink/blue, but says nothing about the third wire which is pink/black. Being it's got black on the wire, I assume it's a ground? This is a manual TPS sensor, manual computer, and manual truck. I've even ran the blue/green and pink/blue directly to the computer's pins and it still won't idle, but if I touch those two pins directly together with no sensor involved it'll instantly idle perfectly, just not rev. The Pathfinder TPS sensor has the 3 wires coming from the main body, and a secondary plug coming from the side. According to the diagrams, it's got a throttle valve switch and an actual throttle position sensor with a full-range potentiometer that go to different pins at the TBI computer. I would assume since the Z only has the 3-way switch those other wires shouldn't matter. Again, I've tried 4 different throttle sensors and they all do the same thing. I don't want to drive the truck much because running as rich as it is at idle is horrible for rings and such. Anyone know what specific wires need to be ran to the computer for the Z engine to run right? Any help is really appreciated. I made a video of it, what hooking pins 18 and 25 directly together does is the same with hooking the TPS sensor up. http://www.youtube.com/watch?v=BrvAravn6pM And a video of the truck going, warmed up, wide open (for fun).
Well, some background info first. I'm a new member here, my name is James and I'm 18 years young. I've always loved working on anything related to cars, and have a love for Pathfinders. I bought my '88 last August after being rear-ended at 50 from a dead stop in my old '87. I've really enjoyed this truck, but as soon as I changed the oil I knew there was going to be problems soon. It came out as black sludge, I was pretty pissed. The motor lasted me from 177K to 194K, which is a pretty good amount of mileage in less than a year. I spun a rod bearing on the stock motor, and swapped in a motor from an '84 Z31 (300ZX) with only 102K. The bare minimum to get the truck back on the road was to keep the factory TBI set up, which is being a little problematic. I've always wanted to swap in a Z31 intake set up even before I blew the motor, so this worked out perfectly. I found the 300ZX on Craigslist for parts, and the guy said he'd take $100 for the motor. However, since his job schedule kept changing he wasn't able to work on the car to pull the motor out for me, so he said that if I came and yanked it I could have the motor for free. I've got a TON of wiring to sort through yet, but it'll be easier once the manifold and stuff is on so the placement will all be correct, to help figure out what goes where. At the moment I'm having an issue with the rear hard line coolant hoses hitting the firewall. I can use the other factory lines if I bypass the coolant lines going through the throttle body. I've heard of a lot of people doing this without any problems.... There's also an issue of fuel pump wiring and some wiring for the gauge cluster that I'll need to sort through and remove from the TBI harness as I slowly work it out of the equation. I've done a lot of research on Z31performance.com, mostly for wiring harness diagrams, pin outs, and what other people have removed/changed to make these intakes work with other vehicles. There's going to be an issue with the air intake tubing as well, I noticed the factory Z31 uses some extreme angles that just will not work on a Pathfinder. I'll figure something out, but likely my truck won't be back on the road for a while now. So far: Original TBI set up. Entire intake removed. The Z31 intake prepped to go on. I'll keep posting pictures and updates as the project goes on. Any tips and advice from some hybrid project guys would be great!