Ok, im changing my coolant temp sensor and figured while im at it i'd change the other sensor right next to it. The only problem is i dont know what it is. Its diretly to the left of the CTS and has a plug on it like a fuel injector. Thanks

 

i believe that's the cold start injector switch

 

You are correct.

 

thanks!

 

Actually I think it's the fan control switch. If it's fairly large in size and has a brown top that's what it is. I pulled mine and replaced it with an aftermarket switch for my new fan setup and the car still starts fine even when the outside air is freezing.

 

heres a pic. how much are the sensors? you mean if that the cold start injector sensor, when a person removes the the cold start from the fuel rail, this sensor can also be removed?

 

Nope. The smaller of the two is the CTS, and the larger with the injector like plug is for the 9th injector. The secondary fan switch is in the passenger side head at the rear.

 

Yes! If you have removed the 9th injector, you can remove this sensor and plug the whole with a pipe fitting plug.

 

That's definately the fan control sensor. The ECU uses it to tell the fans when to come on.

There is no cold start sensor. The cold start injector gets power when the key is in the crank position. The car will even start off of just this injector if the ECU is removed from the car. It will die immediately after you let the key go to the run position though. I found this out when I bought my car and had to troubleshoot it when I finished putting it back together and it wouldn't stay running. The previous owner didn't want to finish it after an engine swap, so the car wasn't running when I bought it. I got it all back together and it would start and then die immediately. I pulled the PCV hose and squirted a little ether into the intake and it stayed running. Eventually I found the problem was two clogged injectors in cylinders that fire next to each other in the firing order (5&7 I think). New injectors got it running again. It was hard to diagnose though, becasue the cold start injector squirts fuel when cranking, and then stops as soon as it fires up. In reality it isn't a cold start injector, but a cranking enrichment injector. Later ECUs incorporate this feature into their logic, which is why this extra injector went away in later TPI systems.

 

OK I am not trying to star a war here with you, but I suggest you do some more research on this topic. The sensor is in fact the CTS "Coolant Temperature Sensor" Which sends the coolant temp to the ECM, it does have a bit to do with activating the Fan, but there is more to it then just that. The other sensor with the bigger plug is the Thermotime switch which controls the 9th injector pulse.

Here is a link in the search section that will give you some more info. https://www.thirdgen.org/techbb2/sea...der=descending

 

The smaller of the two is definatly the coolant temp sensor and controls the fan through the ecm. If you notice it is similar to the IAT sensor and functions the same. The larger of the two is the cold start switch. I have many diagrams and schematics and show the same thing.

 

Well, my 9th injector still works and I don't have this sensor anymore. All the parts books list the sensor in question as a fan control switch. The other sensor is indead the CTS. The sensor in the head is usually for the gauge, but I've never seen on in the passenger's side. Every one I've seen is on the driver's side.

Some book may say that this sensor has something to do with the 9th injector, but my experience has shown me different. In fact it doesn't appear that the 9th injector is linked to the ECM at all. My car started without the ECM plugged in. How? It ran off the cranking shot from the 9th injector. Once the motor used that up it died. Without this sensor the car still starts and runs fine, even when the outside temperature is freezing. If that sensor was critical to the cold start, or warm up it would run terribly when it was that cold outside.

 

I dont think anyone is disagreeing with you about the function of the cold start switch because in fact i have completely rewired my entire harness and it is a direct switch. But the fact is the smaller rounded plug sensor is the cts and the larger square plug is the cold start switch. I dont have to look at any literature to prove this since i have rewired my entire harness myself and have seen where the wires go first hand.

 

As for the sensors in the Passenger head... It is only for a car with the two fan setup. It activates the secondary fan at 220*, and yes the sensor in the passenger head is for the guages.

As for the 9th injector working fine without this sensor??? I can't see it. How can you be sure it is working anyway?? As you can't see it working. And I have seen plenty of 9th injector cars start perfectly fine with this unplugged depending on the temperature outside, as the 9th injector is only activated under a certain temp. Both those sensors on the front of the intake are needed to run a 9th injected car properly.

 

Ah, I don't have a two fan car. That would explain the passenger's side sensor.

I'll have to check and see if the 9th injector fires the next time I go to start the car. Now I'm intrigued. I'll post back and let you know what I find out.