I need to identify this sensor, it's driving me crazy. There is no mention of it in the manuals and my painless harness has no matching connector.
I know the one next to it is the CTS. If it turns out I don't need this mystery
sensor does anyone see a problem with me re-locating my temp guage sending unit to this location from the drivers side head? TIA

 

I know it isn't needed with the painless harness as i have done one of these before. Is your car equiped with cold start? i think it is the cold start temp sensor if I am not mistaken.

 

Shocker is right ... Maybe you have a speed density painless harness or a 89 harness which the cold start injector was eliminated.

 

That’s definitely the cold start temp switch, found on the 85 – 88 tpi’s. If you have the 9th injector (driver side runner), then you’ll need that sensor for the ECM to figure out how much fuel to add at startup. If you eliminate the 9th injector, then the sensor isn’t needed, but you’ll need to change to a different bin file so the ECM can add more fuel to the main injectors at startup.

 

Your car will start. it may take a few more cranks and it may not. I ran mine with out it for over a year. Although that was not optimal for performance either.

 

Thanks guys, makes a lot of sense now. I did buy the speed density harness and I have the 9th injector eliminator plugs, and using th 730 computer with
8D so I should be good to go. SO, any problem moving the temp sending unit to this location? I'm using block hugger headers and they block the hole that is for the sending unit (using World Products heads).

 

That goes right into the water crossover on the intake, so it should work just fine for the temp sender. I've seen other guys use the same port for the fan switch that's originally in the passenger side head too.

 

I am having problems getting my '86 305 motor started when its been sitting for more than a few hours, it wants to just crank and never fires until it gets warm from cranking. Do you know if this cold start coolant temp sensor could cause such a problem? How can I test the sensor and see whether its still good? Also, do you know where the wires from the cold start sensor go?

Thanks.