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JeremiahB
08-10-2013, 03:48 PM
Hey Z31 lovers, my name is Jeremiah and I have a 1986 Nissan 300zx. Recently I have been having some issues with it. My car won’t stay running.

Detailed description of my problem:
When I start the car it will start fine then die within a few seconds. It dies in a “chocking” manner. If I give it gas I can keep it alive but as soon as I give up the gas it will die still.

Today I paid a bit more attention to the way it dies. I can give it gas and it responds but if I hold the accelerator down it won’t hold an RPM for long it will begin to choke If I pump the accelerator every few seconds the rpm will spike and stay alive as long as I keep pumping the gas.

After prolonged periods of keeping it alive after I let the gas go sometimes it will hover below 500 RPM and try its hardest to stay alive but eventually dies. I have noticed my volt gauge moving around as this is happening also.
On my ECU I get code 31. Sometimes I get code 23. After erasing the computer and starting over code 31 pops up always after it dies and sometimes when I give it gas and try to save it at low RPM I can get it to display code 23.

Troubleshooting so far:
Firstly I replaced the fuel filter. Plugs and wires look ok. Battery is good. Fuel pump is fairly new (less than a year) I cant seem to find any vacuum leaks or exposed wires. I noticed my electrical connection to the fuel temperature regulator was off but I connected it back up.

As far as code 23:
I have used the manual to diagnose code 23:
I did a continuity test in pin 18 and 25 on the ECU input harness and the test passes for continuity / resistance when I depress the gas pedal and release it. The flow diagram says everything is fine and I can only get code 23 sometimes anyways.

For code 31
I have a spare ECU, swapped it out, no change. I am fairly confident that at least one ECU is working
Code 31 is about electrical load for the following systems AC/heater, power steering, radiator fan, head lamp, and rear defroster. I started taking out fuses to see if anything made a difference.

I removed 2 AIRCON blower, head lamp, and AIRCON control fuses and disconnected the heating control unit in the interior. I actually don’t have AC so the AIR CON fuses are a bit confusing but I was using a diagram from the web.

I was hoping someone can help me with this issue. My skill level is intermediate do it your self guy (mostly because I can’t afford otherwise so I make do) Everyone tells me to junk this car because it is old but I will never give up on it. Thanks a lot Z31 community

Jeremiah