Hello,

This is my first post so first of all thank you for letting me join.

I have a 2500 Express 4.8 that has developed a misfire problem. The only code I get when the check engine light comes on is P0300. I’m trying to figure out what is going on and hoping you can help.

Aside from the check engine light, the only other thing that seems off is that there is an unpredictable clicking noise coming from the engine. It is more common when it hot, and comes and goes randomly and isn’t in time with the engine.

Other than I can’t find anything wrong. Gas mileage is normal, engine sounds and feels normal. Spark plugs appear ok.

if anyone has any ideas about what I should do next that to figure this out please let me know.

thank you

 

a random misfire could be just about any thing. Until it gives you a code for a particular cylinder you are on a goose chase. It may be bad gas. A failing mass air flow.. a vacuum leak. Low fuel pressure.. anything that could effect every cylinder…I think you will need more info like a live data stream active when it pops the code…

 

What kind of scan tool do you have? With a not too expensive ELM327 and the Torque app you can see the misfire count for each cylinder. It might not be up to the level of setting a code for that cylinder but might still show you something to go off of. Look at your fuel trims, O2 voltage, misfire count, etc.

 

Thank you to all who replied.

I have an actron obd 2. It is able to rule out most sensors, like the 02 sensor.

at one point it went to a shop and there the scanner they had said that cylinders 1,2,5, and 8 had histories of misfiring