ok so I got my 3.4 in with the wiring done with the exception of me having to jump my green-yellow wire ( is it like a fuel pump ground? cuz the pump wont stop with power to the ecu and this wire just grounded normally, as of right now its on a toggle switch) really wish I could figure how to make it proper! Any help would be great?
So I think for whatever reason my ecu is staying in closed loop because theres just no power in the top end while it just dumps gas . I got my fancy smancy little wifi obd 2 reader in the other day from plx devices with the ipod interface but I ran into an epic fail tonight tryin to wire in my obd port only 4 stupid wires and i cant seem to get em right... purple wire, brown wire, white-black and a white-silver rings wire, could one of you oh so brilliant veterans show what these wires go to and which ones stand for what because I cant seem to find them in my wiring dia. anywhere??? I have searched my butt off on this site but to no prevail. PWEASE HELP ME!

 

Purple wire goes to IGN, the shielded wire goes to ECU, and the other two go to ground.

 

the Green/yellow wire does not go to ground. It should go to a relay to engage the fuel pump. It IS the ground that energizes the relay and the relay sends power to the fuel pump.

 

Cool ok wii i thought any power source would work so i just wired in the purple to the thicker gauge red-white wire that was hot with key in on pos. but I'll figure it out today hopefully! Yeah dntsdad i got it wired in to the other relay wire but with the key in on it just primes the fuel pump and wont stop as long as the key is in on that didnt seem right to me so i have a toggle ground wired into it as well to kick my pump when i hit the toggle plus my pump is much louder then i ever remember it being?? Could this be the culprit to my closed loop ecu? Im so close to having it right I can taste it!!! Thanks again guys, yall are life savers!

 

Ok so I got my obd wired in last weekend and was able to pull 4 codes; two o2 sensor codes and the two knock sensors are showing circuit malfuntion??? I was also able to verify that my ecu is running in open loop so thats good but now I'm thinking the knock sensors are whats limiting my top end? Everything is hooked up, o2 sensors and knock sensors. Idk why its throwing those codes... BUT the rear o2 sensor connection is alittle different then whats on my harness maybe its the wrong one cuz I picked that up from a junk yard. I also hit another major snag when trying to hook up my speedo, my truck is a 95 and has the electronic speed sensor so where in the world do I wire that in those 3 wires to the new harness?

 

As far as hooking the speedo up, you need the plug off of your old wiring harness that connects to your tranny. Its a three wire plug that plugs in right behind the tranny by the drive shaft. Then you have to run the wires up into the cab and plug them into one of the main 2 wiring harness plugs. I think it was C2 for me if im not mistaken. I had to splice the hot wire (black/orange) into another hot wire going into the the C2 plug.

 

open loop is bad, not good. You want the computer to go into closed loop. When the computer is running in open loop, it has a really rich fuel map, because it can't determine the proper amount of fuel to supply. Usually because of an o2 sensor malfunction. But it could be from water temp, MAF, o2, and a few other things. like TPS, etc.. green/yellow wire should go to the FC pin on your ECU. If you don't have that then it should go to ground I thought. That's all the computer does usually. Or just get a regular bosch relay and replace the COR with that. Look at the EWD's for the 3.4's. Most of them have a 4 wire relay for their COR's.