P0304 on a 2002 Chevy S-10
Ok, (today is sat 5/5/2012 apx 5:00pm) So I have a 2002 Chevy S-10 with apx 47000 miles its an automatic 4x4 with a 4.3L (whatever the stock chevy V6 is,... its the 350 that is missing 2 cylinders).... so I am getting this misfire only on cylinder # 4 I have recently had some work done on the truck... i will try to give approximate time frames back in january i replaced the Mass Air Flow Sensor.... (that was due to a code that called for MAF reading was high and low and erratic) then in mid february i replaced the plugs and wires... in march i replaced the cap and rotor after all that the truck was running good.... but i went to get it inspected and pulled a code P1345 on the way there, that said camshaft to crank shaft position correlation fault) so i canged the Crank position Sensor i changed the camshaft position sensor... turned out it need a new distributor, the teeth were all chewed up on the gear..... (the truck was running 20deg out of time r**ard at about 1000-1200 RPM) the truck sounded like a champ no one would know it was that bad by listening to it... white the mechanic was test driving for that the P0304 came up (misfire on cyl 4) so they ran a misfire screen on my truck and cyl 1 was showing maybe 10-20 misfires per 1000 and cyl 4 was showing like 50-80 misifres per thousand so they pulled plugs for 1 and 4 and told me the bosch split fires that i put in there were not really recommended for that truck so they put in some AC Delcos .... still showing p0304 I have the truck inspected now but the code keeps coming up..... i have changed sparkplugs (just switched which cylinders to see if the misfire would move to a diff cyl to indicate a bad plug) i have changed the plug wires (just like i did with the plugs) still no change i noticed i used a lot of dielectric grease on the wires so i cleaned all that out and still get a miss on cyl 4 here is the big kicker sometimes the SES light will go out but i can scan it with my scan tool and it still shows a "Trouble Code" this scanner has both pending codes and trouble codes... i was under the impression that a pending code will come up when the vehicle detects something once.... a trouble code will come up when it detects it 3 times in a certian amount of time and if a trouble code comes up then the SES light would then automatically illuminate why is this doing this? if my cat was plugged then i would have a miss on more then just one cyl right?? could it be my PCM? how do i test that? how hard is it to change? I want to drive the truck over a cliff.... any suggestions
Just because the SES light goes out, the code(s) are not immediately erased from the memory...otherwise your description is correct. Put a noid light on Cyl. #4 and see if it blinks. Swap the injector with another cylinder and see if the code moves. Perform a leak-down test on that bank.