Cold Advance Temp Sensor Failed.

[Tim Sothard]

I just replaced my injection pump and injectors which was a well needed task. The few days afterwards I was crazy surprised how much more power I had, and then I started to get worried about the different sound my motor was making. A while before that I had a shop replace my stock exhaust system with a 3" system with thrush pots. So its always been loud but not this loud. She started making the nappy ragged out diesel tone that's tellin ya its at the top of its RPM band between 45 and 55. One morning starting it I realized that my high idle wouldn't kick down so I unplugged the lead. Good deal, still had the intermittent high rpm sound. Did some looking around on here and figured out that my Cold Advance Sensor went bad, and I guess it changes the timing of your injection pump. If that's the case Im wondering how bad is that is to run the motor that hard for a week?? Glad I realized what was going on and didn't just think that I had all this newfound power from a new IP pump and injectors!!!!

 

[Barrman]

You unplugged the green wire from the fast idle solenoid. Now, unplug the other green wire from the cold start advance solenoid. Your engine sounds should be back to normal.

Now, look at the very outside back edge of the passenger side cylinder head. Below the valve cover but above the exhaust manifold you will find a sensor with 2 wires on it. The green wire is the other end of the two green wires you have unplugged on the IP. The other wire is hot 12 volts. Unless they are touching somehow, your sensor is bad.

It is officially called the cold advance and fast idle temperature switch. When swapping them, make sure the engine is cold, you have the new one in your hand and I would suggest doing the work from the top. Coolant will leak, but if you are fast and the radiator cap is on. Not much will leak out.

 

[magic marouke]

You unplugged the green wire from the fast idle solenoid. Now, unplug the other green wire from the cold start advance solenoid. Your engine sounds should be back to normal.

Now, look at the very outside back edge of the passenger side cylinder head. Below the valve cover but above the exhaust manifold you will find a sensor with 2 wires on it. The green wire is the other end of the two green wires you have unplugged on the IP. The other wire is hot 12 volts. Unless they are touching somehow, your sensor is bad.

It is officially called the cold advance and fast idle temperature switch. When swapping them, make sure the engine is cold, you have the new one in your hand and I would suggest doing the work from the top. Coolant will leak, but if you are fast and the radiator cap is on. Not much will leak out.

i have a couple of questions . do i put the new one in with nothing on the threads ( if it needs to be the threads that ground it) ?

my plastic wire plug is melted so was going to just push the two wires on without it . does it matter which wire goes on which tab on the sensor ? thanks

 

[dougco1]

The new sensors come with a thread sealant already applied "See photo".

As far as your wires are concerned, the sensor acts as a switch. 12 volt in one side and when cold it stays energised "normally closed circuit". As the engine warms up it opens the circuit/switch preventing 12 volt power returning back to your injection pump that advances your timing.

As for your melted plug you can attach the wires to the prongs the best you can. I would just get a new/used plug and splice it in.