P0300 code for 2000 Silverado with 4.8L engine

Symptoms:

P0300 code-random misfire after an engine computer scan. Performed chemical tune up for top end, swap ignition coils and injectors including tune up but bank 1 cylinders still showing code of misfire. Could this be another catalytic converter problem?

Basic Concept:

It looks like this is a catalytic converter (CAT) failure if misfiring is concentrated in just one bank. Again this can be tested by a vacuum gage hooked up at the exhaust manifold of bank 1 as in previous blog.

Repair Strategy:

Another test that can be done on bank 1 CAT is to measure the voltage of the oxygen sensor located after the CAT. Normally, the signal voltage will fluctuate from 0.4 volt to 0.7 volt. If the reading is not around this range, the CAT is definitely bad. For more details in testing the CAT including the wiring diagram of the oxygen sensor wires, please contact ATS.