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Q: My impala will start but it will not run.

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ive replaced the cylinder heads and radiator and installed a new thermostat. i also had to get another 2 wire for my ignition module. now my car starts but wont run. to get it to start i have to press the gas at a certain time to get it to fire up and after then when it does it starts to idle low and shut off. then after it warms up it sometimes starts and runs till i put it in gear and it shuts off. so far i have checked the mass air flow unplugged it still shut off. next i checked the intake air sensor i shook the wire and it shut off checked the voltage on it and its getting 5 volts. and ive checked and cleaned the idle control valve and still it shuts off

My car has 230000 miles.
My car has an automatic transmission.

A: Hey there: Anytime you remove cylinder hea...

Hey there:

Anytime you remove cylinder heads, intake manifold or disconnect the fuel system, it’s important to clear any OBD-II error codes that may have been triggered either prior to the removal or after you started the vehicle.

The issue you’re describing is commonly caused by a communication error from the ECM to the air fuel ratio sensor, O2 sensors, and the throttle body itself. The system will permit initial flow of fuel to start the engine and keep it running while the throttle is depressed.

This might sound simple, but download and clear any error codes with a digital scanner. If this doesn’t solve the problems, contact one of our local ASE certified mechanics to diagnose your stalling issue by inspecting your Impala’s fuel and ignition system.

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