4.2L Intake Manifold Sensors

**Jims-87YJ** · 05-01-2012, 12:19 PM

OK I am in the middle of a tear down on my 87. The Jeep has a Weber Carb, its been nuttered and the ECU has been removed. I want to pull any wiring and sensors that I no longer need. To that end I am trying to identify all of the Temp sensors in the intake manifold. I know what the CTO valve is and am keeping it but the other three sensors i am not sure?

One should be the sensor for the manifold heater (want to keep this one)
and I am not sure on the other two, as I have not found a good diagram for these. Any help would be appreciated.

Here is a picture:

Thanks again

CB10101 · 05-01-2012, 08:42 PM

#1 is the coolant temp sensor. Can't help on 3 and 4. None of those were hooked up on mine

CB10101 · 05-01-2012, 09:11 PM

Pretty sure 3 is the knock sensor and guessing 4 is the manifold absolute pressure (map) sensor from ch 6 of the haynes manual

timatoe · 05-01-2012, 10:18 PM

#1 Coolant temp switch http://home.sprynet.com/~dale02/coolant.htm
#2 You already know is the CTO
#3 Knock sensor http://home.sprynet.com/~dale02/knock.htm
#4 Temp sensor that triggers the manifold heater below the carb. http://home.sprynet.com/~dale02/manifold.htm

There is no MAP sensor on the 4.2.

**Jims-87YJ** · 05-02-2012, 05:16 AM

Thanks everyone, I forgot all about Dales great site

.
So if I am nuttered I should be able to pull both #1 and #3 correct? The ECU is coming out also.

timatoe · 05-02-2012, 08:09 AM

You could pull #1, #3, and #4 if you wanted to. Several guys here don't run the heater, but I probably still would living in PA. But certainly #1 and #3 aren't doing anything for you anymore.

**Jims-87YJ** · 05-02-2012, 08:40 AM

Ok Thanks That what I thought but always like to make sure. Yes I think I will keep the heater although I am not sure it even still works? I will have to figure out a way to test it. Thanks again for the help.