2003 Kia Spectra Troubled Misfire

have you checked to make sure the injector is getting continuous power?

Yes as it is misfiring the injector is still operating electrically and mechanically. I put injection cleaner in the cylinder let it sit for a while and tried to clean up some of the carbon, because when the car starts to misfire (under load) it pings pretty loud so I naturally suspected detonation/pre-ignition. Yet this problem still persist to be annoying

Have you checked the knock sensor? Here is the test procedure. I was able to dig it up for you.

Disconnect the sensor electrical connector.
Remove the sensor from the engine.
Mount the sensor in the jaws of a bench vise.
Connect a voltmeter between terminal 1 and 2.
Wrap the bench vise sharply with a hammer and note the voltmeter reading.
Verify that the voltage spike is less than 1 volt.
If no voltage spike is observed, replace the sensor.


NOTE: You need to remove the intake support bracket to access it.

Let me know. It plays with the timing and can cause the noise under a load, so it's worth checking.

Joe