Having problems with your 2004 GMC Envoy ?
ERRACTIC RPM I HAD MY THERMOSTAT REPLACED ON A 04 GMC ENVOY XUV 4.2L BECAUSE MY CHECK ENGINE LIGHT CAME ON. I TOOK IT TO AUTOZONE AND THE CODE STATED THAT WAS THE PROBLEM. ON THERMOSTAT WAS REPLACE THE BATTERY WAS DISCONNECTED-RECONNECTED TO RESET COMPUTER. NOW WHEN THE A/C OR THE DEFROST IS ON, I NOTICE THE THE RPM GAUGE WOULD BE VERY LOW AS THOUGH THE CAR IS LOSING POWER-THEN IS GOES UP! SO THE RPM GOES UP AND DOWN WHEN THOSE COMPONENTS ARE ON. WHAT COULD BE THE PROBLEM. THANKS!
Clean your throttle body. Once the battery is disconnected and the computer reset, it no longer increases power to make up for a dirty throttle body. Get a $4 can of carb cleaner. If you go to a mechani9c they will tell you that it is the ac compressor.
Repair Help & Product Troubleshooting for 2004 GMC Envoy
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