I keep getting a random cylinder misfire code?

CORMARO414

MEMBER
1999 CHEVROLET TAHOE
V8
2WD
AUTOMATIC
119,000 MILES

I keep getting a random cylinder misfire code. When I drive on the highway and have the throttle at about 3/4 or full throttle after a little bit it starts to misfire. The engine light starts to blink then it stays on. It will misfire for a little while then go back to normal. It also does it when I race it. I'll floor it and when I let off and give a little gas, it will be doing it. Or if I am drag racing at the track it starts to misfire towards the end of the track. I have a new fuel pump, fuel filter, spark plugs, plug wires, distributor cap/rotor, had the injectors cleaned, MAF sensor, intake, cleaned the throttle body. O2 sensors are my next guess. What do you think?

1 Reply

DANNY L

MECHANIC
5,648 POSTS

Hello, I'm Danny.

Are you just getting the code P0300? The best thing to do is perform a check engine light diagnostic test . Here is a tutorial showing how to perform a check engine light code test:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

After performing this get back to us with any code information on the misfire and we can the properly diagnose the issue on your car. To determine which cylinder is misfiring you will get any code from P0301-P0308 depending which cylinder is misfiring. The last digit of the code is the suspect cylinder. Hope this helps and thanks for using 2CarPros.