Mystery water temp sensor
 

I am working with a 1979 280ZX.

There is a one wire sensor (single green wire about 2 inches long) coming out of the thermostat housing (water temp sensor I assume) that when disconnected causes the engine to run so rich that it will not stay running.

Reconnecting the wire caused the engine to return to normal operation.

The wire to this sensor was broken and my local parts stores do not have a listing for the part. They only show two wire sensors.

Can anyone here give me a part number and a source for this sensor?

I have re soldered the wire on the sensor but it looks too fragile to trust long term.

Also an online referance to a wiring diagram or manual for the 79 ZX would be helpful.

Thanks,

Mike

welcome to zdriver mike, you can try courticy nissan, but from all the nissan dealers ive been to, they cant get it, even special order. so got to the wrecking yard to get one. and yes the car will run rich when unpluged, it goes into cold start mode, and the ecu enriches the mixture. to compensate for the wire being unpluged, on 79 and 80 only, unplug the cold start valve, the it wont get extra fuel. look in your haynes manual to locate the cold start valve, and this is only temperary till you find a new one.

^ The cold start valve only operates for a few seconds when first starting the car. It doesnt operate while the engine is running.

As far as the coolant temp sensor goes: Ask for one for a 75-78 280Z. They used the same engine temp. sensor as the one found on the '79 (those that have the sensor in the thermostat housing anyways). Unfortunately if you try to source that part for a 280zx you'll end up with the cylinder head temp. sensor, which is the two wire unit.

www.blackdragonauto.com and www.zcarparts.com both carry the sensor you're looking for. But you'll have to look under the 280Z (not ZX) to find it. If you try the dealer and tell them you want the sensor for a 280Z (again, not for a ZX) then they might be able to get it for you as well.

Ohhh I Might Have To Pull That From The Junk Yard Along With Some Iron Crosses

on the 79 280zx, the factory service manual, states that that cold start valve works in more situations than you think, it actually comes on at different times for enrichment because we dont have o2 sensors, so it uses it pathetic little brain to do weird things, i actually have a chart as to when it comes on and off. and good to know aboot the 75-78 sensor thing j, cause i cant get that dang thing anywhere, and mines screwed, it works only when it feels like it. the wire has close to the same fate as mlstraws sensor.

I see. I guess CSV opperation on them is different then the later O2 models then. Thats nice to know.