Ok Heres My Issue. I Have A 2000 Silverado 2wd 4.3 And When Im Bout A 1/4 -1/2 Throttle The Truck Wants To Misfire. But After I Have Been Driving Mutiple Times In A Day It Will Eventually Stop Most Of The Time. I Have Replaced Plugs, Wires, Cap, Rotor, Throttle Postion Sensor, Camshaft Sensor, Map Sensor, Fuel Filter, Cleaned Mass Airflow. I Have A K&n Filter And A Throttle Body Spacer. I Run Lucas Fuel System Cleaner Every Other Tank. When I Hook A Scan Tool Up All It Says Is Code P300 Which Is A Multiple/random Cylinder Misfire. If Anyone Has Any Ideas Could You Please Help. I Have Been Dealing With This Issue For Almost A Month Now.

 

is it getting really shitty gasmileage???

doubble or tripple check your coldair intake, you may have a "leak"

causeing a lean condition

did you reset your pcm after you replaced each of those components?

 

gas mileage is not that noticable. i dont have a cold air intake just a k&n filter. and i disconnected the battery while i installed everything

 

I had a similar issue once. I chased it for weeks. I finally discovered the injector wiring harness was not making a good connection to the injector. The harness had 12v and ground but the terminals inside the harness were spread apart enough to give me intermittent misfires. When the truck warmed up it would sometimes go away. (Metal expanded I guess and made the connection) Pull your harness and see if the internal contact are corroded or loose etc….

 

now theres something i can work with. what did u do to remedy the problem? i appreciate this so much i have been trying so many things asking so many friends then a customer came into autozone the other day and said check out this forum. anybody else have any ideas? thank again!!!!

 

I was able to scan the PCM and it told me which injector was misfiring. I unplugged it and squeezed the metal back together. My harness connection forms a metal box. Its cut in half and is supposed to slide over the injectors post (one 12v, one ground) and sort of squeeze the post. Its not a very good design but what can I do. I squeezed the box back together so far it collapsed on itself. It took a pretty firm push to get it back on the injector. That is how it should have been designed in the first place.There have been a couple of others who had this happen as well. Good luck.

 

any other suggestions before i tear into my intake plenum?

 

any thoughts on maybe it being the fuel pressure regulator?

 

pull the vacuum line on the fpr. is there any fuel in it? try it while it is running as well. what happens?

 

prob with that is that with the 4.3 u gotta pull the intake plenum off to get to all the injection stuff. i dropped it off at chevy today anyways and they spent nearly 7 hours trying to diagnose it and then they said they wanna keep it overnight to continue with it tomorrow. my next step is to hire an exorcist. lol