Hi guys I have a question I own a 2002 Silverado 4.3 liter 4wd automatic the ob2 says the #4cyl is misfiring. I changed the plugs, wires, cap, rotor, and reset the computer and 15 min later the check eng light came back on. The motor does not seem to be misfiring I am kinda lost if anybody has any suggestion I would definitly appreciate it
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01Softail, did you ever figure out the #4 misfire problem? I just got an 02 with a 4.3 for my son. it has 120k and is having the same problem. has had the problem for 20k been to a couple dealers who went as far as changing timing chain and gear. I had it in the shop for a week and they did compression tests, injector tests and couldn't figure it out. I changed plugs, wires, cap an rotor, ran sea foam, premium fuel (won't run ethanol in anything). I'm about to start looking in to rebuilt heads. Dealer and Chevy mechanics have been worthless!
I´m having the same problem on #7 cylinder, i already changed the spark plugs, the wires, swaped the coil from another cylinder, cleaned the throttle but non of those worked because the engine light is still on after being cleared. tomorrow i´m gonna take my truck to the shop to get the injectors cleaned and i hope that works.
If you have a 4.3 need to check fuel presure after ignition cycled on maybe fuel presure regulator leaking in intake causing misfire,the 4.3 does not use seperate coils but the 4.8 and 5.3 due for those with the v8s listen to injectors with long screwdriver on lower protion and listen for the click sound to see if they sound like others if they sound good gooing to need to do running compresion test and injector drop(balance test).Hope that helps.