Topic: Z31 300ZX Running issue..
Ok...so not Lemons related. But I know theres gotta be at least one Z31 300ZX guru in here..or at least a nissan guru(Im looking at you Sasha). Ive raced against a few of them. So I have a customers 1987 300ZX automatic here at work thats been sitting. Has an issue where once the car gets hot, it randomly starts idling rough, wont rev, and when you try to rev, it backfires through the intake and would usually start running worse and worse till it stalled. Has codes 12 Air Flow Meter, and 41 Fuel Temp Sensor(Broken sensor..which as i understand doesnt really do squat). Started diagnosing the MAF and voltage readings out of the sensor seemed slightly questionable. So replaced the MAF, cleaned and adjusted any questionable pins in the connector, cleared codes and started from started over. Car ran for almost and hour in the bay...and would rev freely without issue(cant roadtest the car at the moment). Then randomly one of the times i went to rev it....got the back fire and wouldnt rev. And of course would start running like crap. And the code comes back. Voltage outputs and inputs as well as grounds at the MAF are normal. Everything between the MAF and the ECU ohms out correctly. Checked all the basics. Has good fuel pressure...in fact the pressure goes up when it starts running shitty...telling me the injectors are cutting off fuel. Has good spark...courtesy of a new coil. Started questing the throttle position sensor. Then discovered its a switch and a sensor all in one. Switch seems to be working properly..but dont get a 5 volt reference to the sensor portion. But i find conflicting information on all repair programs at work and online as to whether the tps sensor is even controlled by the ECU or the trans controller. Nor can i find where in the ECU plug the wire would go to. One page will the say the switch controls the trans and the sensor controls the fuel....another will say its the opposite, another will say it uses both for fuel and the trans. Found a diagram for a car one year newer that told me what pin on the ECU went to the TPS....but that pin doesnt have a wire going to it. Im going out of my mind with this thing. Someone please point me in the right direction. Or am I completely stupid and is that fuel temp sensor is causing all of this?