TwinTurbo.NET: Nissan 300ZX forum - Not sure what the issue is please help.
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Subject Not sure what the issue is please help.
     
Posted by NoluckWill on June 12, 2017 at 7:31 PM
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Message Alright, this is gonna be a long explanation for you, but I'm going to give you every detail I can so hopefully one of you can lead me to something so I can finally enjoy my Z. So here we go. Starting back in 2015, I started having an issue with the car running really rich and not making the power it had before, which then slowly became a misfire and the car not wanting to start once the engine got to operating temperature after I had shut it off. After chasing my tail and pulling some codes I learned it was code 13 temperature sensor which in my mind was causing the ECU to think it was way hotter than it was so it would run rich to try and save the engine. The connector to the sensor was badly repaired and the wires had basically melted together after a few years of abuse come to find out. I replaced it and it fixed the problem. So after breaking some other connectors and I had an issue where the EGI and Fuel pump relay had a constant 12 volts after turning the ignition off, so to remedy the problem at the time I spliced into the fuse box by the battery tray and ran a 300 amp kill switch to cut power to those relays and spliced in another toggle to the power wire for the entire car and they are both still currently in the car. So after getting tired of that I went out and bought a brand new Wiring Specialties harness to get my car back up and running. So throughout the last year I have put this new harness in, completed a throttle body coolant line delete, rewired my Spal 16" fan to a toggle switch from the existing Spal fan harness, Relocated the battery to a box in the trunk (I ran brand new 2 gauge wire from the trunk to a junction post along with the wire for the starter, fan power, and fuse box power, and I may be forgetting some small stuff). So, I got the car back together and after starting it a few times I realized that the car shut off when I turned the ignition off which was the main reason I had got the new harness. I still had a miss fire though, so I replaced some vacuum lines and corrected my intercooler piping. So this brings me to the current situation. I now still have the same symptoms as if my temperature sensor is not reading. The car no matter what will start when its cold and has no heat in the motor, but it will not go into a closed loop and idles between 500 and 1000 rpm, but if I try to start it after getting it to 180 degree it will just crank and crank like there is no fuel or spark. I figured out when that happens if i disconnect the temperature sensor and crank it for a minute it will clear itself out and start, but run super rich and die unless I plug the sensor back in. I have pulled the codes getting code 13. So I warrantied out the sensor and figured that would solve the problem...which it did for about one start up. So I chased my tail again checking all of my connections, making sure I do not have any more boost leaks and even redid some of my couplers on the intercooler. So I continued to have the same issue. I warrantied out the sensor again. The car still has the same issue and the same codes (code 13 again). I am now onto my 4th or 5th sensor. So this past weekend I decided it had to be something within the harness and I broke out my multi-meter and checked the resistance on the sensor and the connector itself. So I found a thread on here that had the specs of the sensor and took the readings and it was 2.3 kohms of resistance without any heat in the engine which is good. I then checked the resistance of the connector and was getting 1275 ohms throughout the harness(which I now realize is off due to me leaving the ecu plugged in when checking this). After seeing this I emailed wiring specialties to see if they had any suggestions since they were the ones that built it. Yury (the owner) emailed me back same day and suggested I check the continuity on pin 30. So I went ahead on to check the continuity of the wires for pins 28 and 30, from the sensor connector to the pins in the ecu, and they both have the 1 ohm of resistance throughout the harness. So I still was skeptical and was pretty desperate. So after consulting a good friend of mine and almost splicing into my brand new harness (which I did not thank god) he suggested since I still had my old crusty rats nest of a harness to depin the old wires and take the old connector which I had replaced long ago, and make a jumper harness to get away from any resistance I was getting through out the entire harness. So I depinned the my new harness made my little jumper and put it in my harness and the car actually ran a lot worse, to the point it died on me and still idled at 500 rpm. I am completely lost and I am running out of options. My current thoughts are that some how back when I had that old harness it could of done something to those pins or capacitors or whatever the sensor goes to and now the ecu has an issue. If you have any suggestions on what to try next please let me know. I am currently separated from the car for 2 weeks. I called and talked to Z1motorsports about them testing the ecu in another car since its their upgraded ecu. I am currently at a loss and do not know where to go from here. If you have any questions about what I did or how I did it that may have caused an issue please ask. Any help is appreciated.

Thank you for reading this all of this.

Will

     
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