GM 3400 / 3100 3.1 3.4 Engine Misfire Cause & Causes Miss Missing P0303
Here is a video for fellow GM
3400 &
3100 liter engine owners. Have a misfire? This video explains the causes for what could be causing the problem.
Mine showed up as a P0303 cylinder 3 misfire. Couldn't figure it out, but finally did. The spark plug and wire were replaced along with a new coil. Could hear the injector firing with a stethoscope but still had the miss.
Found out after tearing into the intake that the lower intake was cracked.
If your car is missing out, first try the following.
Check for spark and check the spark plug, wire and coil. A test you can do if it randomly misses is in the dark, spray a mist of water around the plug wires. If you see blue arcing, you've found the problem. But be careful not to zap yourself, IT
HURTS!
If the spark is good
the listen ...