22RE coolant temp sensor check?

[toysports2k]

so i've been trying to chase down this problem of running rich. i finally broke down and bought a multimeter and started running sensor checks per the Haynes specs. i got solid readings on all the sensors except the coolant temp sensor. the manual says to run the motor up to temp and stick a thermometer on the head near the cold start/coolant temp sensors and compare the fluctuations in the resistance with the gradual cooling of the motor. i took a bit of a shortcut and relied on a mildly warm motor and no thermometer. my results? not a durned thang! was i a chump for cheating? the way i read the chart, even a room temperature motor should give some reading.....

[qsd-dan]

Sounds like you found your problem. You should have a reading of some sort.

[toysports2k]

that's kind of what i was beginning to think. wouldn't i have gotten an "engine check" flash though if it's dead?

[qsd-dan]

Originally Posted by toysports2k

that's kind of what i was beginning to think. wouldn't i have gotten an "engine check" flash though if it's dead?

That comment sounds familar. I have no reading between the two terminals on my auxillary air vavle and yet I have no check engine light or codes. Only the mechanicle part of it is working so I still get a fast idle when cold, but I have an open in the heater circut somewhere. Strange....

I'll test my coolant temperaure sensor in the morning and report the results to you just to make sure your problem isn't a normal occurance.

[qsd-dan]

Just checked the coolant temp sensor (water thermo sensor according to the factory service manual). At first I didn't get a reading. Looked up in the manual and noticed that it is measured in K ohms (1000).....duh, I should have checked that first. Mine reads 2.55 k ohms with the coolant temperature at about 65 degrees. Pretty much on the money according to the manual. My year is 1984 so the readings may differ from yours. Check the resistance at a higher scale on the meter and see what reading(s) you get.

[bvenvert]

I am trying to chase down a similiar problem with my 86 Turbo Pickup. When the vehicle is started cold, the motor starts right up and goes to fast idle. Once the vehicle reaches normal operating temperture, it has a tendancy to allow the idle to drop down to 600 rpms, which is fairly rough running. If i shut the vehicle off after it reaches normal operating temperature, it takes about three tries to get the vehicle to start again and the idle never really reaches 750 rpm. I am wondering if my auxillary air valve is working properly. If I understand the Haynes manual, the auxillary air valve has a thermo sensor inside that regulates the air flow based on the coolant temperature. I wonder if my truck overheated in the past, and then thermo sensor in the auxillary air valve may have become damaged so that it no longer operates properly. Could it be creating an air flow problem on the system that would make the car lose it's idle as the coolant heats up and also make it hard to start after it warms up.?

[toysports2k]

chalk it up to my inexperience with a multimeter....... i didn't have it set correctly on the dial. i ended up buying a new sensor from the dealer (not cheap by ANY means!!) based on my incorrect readings. i dumped the old sensor in a bowl of hot water, then cold water and it is actually reading straight up by the numbers in the Haynes manual. BUT I'M STILL RUNNING RICH!! the rich condition started after putting in heavy guage grounding cables. i originally thought maybe the increased efficiency of the grounding was causing problems with the sensors so that's why i started checking them all. sounds silly, eh?