03 Avalanche misfire?

chevrolet
avalanche

#1

My 03 Chev Avalanche is giving me a P0300 code (multiple or random misfire). With no distributor or individual coil is this something I can fix myself or is it shop time?


#2

You can probably replace the plugs and wires yourself. The plugs are due at 100K. And yes you have CNP (coil near plug) ignition, so you have eight coils.


#3

This came on suddenly. Does this point to a ECM problem?


#4

My guess would be a failing crankshaft position sensor or a faulty connection at the sensor plug.


#5

Most likely not. Change those plugs, see what happens. I certainly wouldn’t wait until 100k to do it.


#6

Find The Main Engine Wiring Harness Ground Wire Where It Attaches With A Nut Or Bolt To A Cylinder Head (I Believe The Right Head) And Make Sure It’s Not Corroded.

This wire grounds the ECM and some have been found to rust / corrode and set misfire DTCs. If it’s not clean then remove it, clean it, and reinstall it.

CSA


#7

I would also stick a fuel pressure gauge on it.