2003 Monte Carlo SS trouble idling, and temp

Asked by CJSCHS2019 Mar 11, 2021 at 01:34 AM about the 2003 Chevrolet Monte Carlo SS FWD

Question type: Maintenance & Repair

Just bought a 03 Monte Carlo from a friend of mine. We've been working on
it for a bit before he sold it to me, and it still has two main problems that are
baffling us. He replaced MAP sensor, TPS sensor, thermostat, IAC valve,
and other things. It's main problem is the temperature, and a constant high
idle. Sometimes, it will idle like normal then slowly begin to go higher and
higher till around 2,000 rpms. While having this high idle, it causes the car to
accelerate when in gear. The temperature is also something that is odd.
Heater core, and radiator have been flushed, and thermostat change, but it
seems like it still tends to get very hot. Any suggestions?

2 Answers

26,810

Did you get a trouble code relating to any sensors you replaced? You should be able to check sensor signal and compare to idle spec for that sensor. I always try to check component wiring circuits before replacing. With high idle, in your drive-way, transmission in park, block off the mouth of throttle body, should kill the engine. If very little or no effect on idle, you got false air getting in there from somewhere? when problem is ongoing, your cruise control isn't engaging? Did you clean throttle bore and around throttle plate?

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