Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP
When you cleaned the throttle body was the key in the on position?
You may need to reset the throttle position sensor. This is easiest with a scan tool, but can be done manually.
As for the p0449 this code indicates a faulty evaporative canister vent solenoid. Have you replaced that solenoid before?
At this point you will likely need to perform a throttle position relearn with a scan tool, or reset the throttle position manually to get the idle back where it should be.
The vent solenoid is fairly inexpensive- about $30 for the part at most parts stores.
Your best bet would be to try disconnecting both battery cables and hold them together for about 1 minute. This will clear the memory in computer controlled modules. Then have someone hold the throttle plate closed while you reconnect the battery cables. This will set the closed position for the throttle body. Make sure the key is off the entire time.
It sounds like you still have something wrong in the throttle body or a correlation problem between the throttle body and the pedal position sensor.
Will your scan tool perform the relearn? Most basic scan tools won't.
There are none that I can think of that would do it inexpensively. Are you seeing any trouble codes stored at this point?
Let me see if chevy has any ideas on this one.
According to chevy that is a sign of the throttle body needing replacement. There is a problem that develops in the actuator where it won't return to closed once the vehicle is warmed up.
It would be best to use a scan tool, but you could try the manual re-learn. It wouldn't hurt anything if it doesn't work. You would just need to run it to a shop that can do the programming. It would most likely start and run, but the idle would be off and the check engine light would be on.
Let me know how it goes if you decide to replace the throttle body.
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Let me know if you need additional info.