code 300 cylinder misfire??
Thread Starter
Racer
Joined: Jul 2003
Posts: 446
Likes: 1
From: Washington PA
code 300 cylinder misfire??
I got this code today after letting it run for the first time in a couple weeks, ran fine, it got warm and the idle started to stumble a little. I erased the code and it seems to be fine now. What casues this?
Thanks
Thanks
Race Director
Joined: Aug 2000
Posts: 14,130
Likes: 7
Cruise-In II Veteran
Re: code 300 cylinder misfire?? (96redvette)
Many many things can cause this code.
Most common are plugs,wires,ignition,opti,02 sensors,etc.
Other causes are carbon build up,bad injector(s),bad ecm,low fuel pressure,intake manifold vacuum leaks,etc.A leaking egr can cause this too.
Crazy huh?
I chased one down on a 3800 3.8 V6 engine(code 300 random misifre) and replaced everything I could think of.It only happened once in a while and drove me nuts.Finally replaced the ecm and it was fixed.The day I caught it,the scanner was hooked up and it showed me which cylinder was not firing properly and further testing showed the ecm was not firing the injectors right.
If the code comes back and the car misses,you may need a tech2 scanner hooked up to see which cylinder(s) is showing up "weak" on fuel/spark
to narrow it down faster.Do check your wires and make sure theres no arcing or if one is touching a ground somewhere.
You may need to do this at night time when its dark enough to see spaarks or arcing.
:)
Most common are plugs,wires,ignition,opti,02 sensors,etc.
Other causes are carbon build up,bad injector(s),bad ecm,low fuel pressure,intake manifold vacuum leaks,etc.A leaking egr can cause this too.
Crazy huh?
I chased one down on a 3800 3.8 V6 engine(code 300 random misifre) and replaced everything I could think of.It only happened once in a while and drove me nuts.Finally replaced the ecm and it was fixed.The day I caught it,the scanner was hooked up and it showed me which cylinder was not firing properly and further testing showed the ecm was not firing the injectors right.
If the code comes back and the car misses,you may need a tech2 scanner hooked up to see which cylinder(s) is showing up "weak" on fuel/spark
to narrow it down faster.Do check your wires and make sure theres no arcing or if one is touching a ground somewhere.
You may need to do this at night time when its dark enough to see spaarks or arcing.
:)
Thread Starter
Racer
Joined: Jul 2003
Posts: 446
Likes: 1
From: Washington PA
Re: code 300 cylinder misfire?? (Bill's86Coupe)
I have changed to following over the past 7 months: opti, water pump, both converters, corsa cat-back, all 4 O2 sensors, plugs, wires.
maybe I will check for arching wires. taht sounds like the most likely
THanks
maybe I will check for arching wires. taht sounds like the most likely
THanks
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Re: code 300 cylinder misfire?? (96redvette)
For my driver, it was the injectors, but GM warrants that particular system for 100k in CA. You might want to check Bulletins - you can least get the titles at http://www.alldata.com or http://www.nhtsa.gov - Also, if you have less than 80k the ECM is covered under the Fed Emissions, so you might just want to have a Dealer take a peek at it.
