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mr_whirly

Coolant Temp Sensor Q

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Had a strange problem pop up today; '88 turbowagon- running great, I pull in for gas, fill tank, jump back in, no start.

Cranks over, spark is good, (plus new cap and rotor) -finally after 20 min it started, but runs very rough now. Check engine light on intermittant; fault code 21- which I believe is coolant temp sensor.

Anyone seen a bad temp sensor cause rough idle like this?

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yes, it keeps the car from running aggressively enough to run very hot, since the sensor doesn't promise that it can tell the computer how hot the engine is. check the wiring pigtail on top of the sensor (inserts to the manifold vertically, near the PCV valve. i think the wires are green and white on my '86)

i've had the code come up from a sloppy wiring repair i did, improving the repair fixed the code. it could be the sensor itself as well of course.

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Follow up: Yes the connector on the sensor was badly corroded.

I just went ahead and replaced the sensor ($17) and cleaned up the engine harness connector as best I could.

Runs great now

-thanks.

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