I changed my plugs used ACdelco irridiums. As soon as I started it up I had misfire issues and my engine light was blinking. Since then I have gotten a code for misfire on #6. I reset the comp by removing the Neg. Terminal and swapped the #6 coil with #2. I have not gotten another code but I feel ot runs rough, misfires and nearly dies at idle. I changed the oil pressure switch and fuel filter. Done the seafoam and cleaned throttle body front and back side. Any advise would be greatly appreciated!
Engine rough and misfire issues
- Thread starter 02VOY
- Start date
One of your other coils could be mis-seated on the plug, or gone bad from handling during the plug swap. Or it could be a rare bad plug. Any new codes?
Pulling one coil at a time and seeing if the engine changed behavior is another troubleshooting tactic.
Pulling one coil at a time and seeing if the engine changed behavior is another troubleshooting tactic.
Ace1875
Member
- Mar 29, 2012
- 276
the roadie said:
I agree the roadie on this troubleshoot, sometimes the little weather strip on hood gets old and rot away then lets the rain water tinkle down ur resonator on to ur coil. although there is a gasket my #4 went bad. when i was replacing that coil i checked and saw my other coil gaskets where looking pretty bad also. so i changed the weather strip by the firewall and replaced the coils along with the plugs.
i changed the coils cause the truck has well over 135k and wife takes the kids to school in it. but u can also just buy the gasket for the coil, instead of changing all the coils.
Also do a visual inspection of your camshaft actuator solenoid. if its covered in oil time to replace that also. These can also be the cause. remember to clean it with some electrical connector cleaner and get all that oil & dirt out before plugging in the new one.
- Apr 7, 2012
- 103
I had the same misfiring issues after changing plugs. I removed and reseated all coil packs again and cleaned the throttle body while the air box was off. After that she ran like new. 
Had a similar problem with my wife's Rainier when I bought it at about 40k miles and used the misfire to negotiate the price down. It took three times in the shop for them to figure out there was a broken spark plug after they replaced the PCM. Of course the bumper to bumper warranty was still in effect. Still can't believe how inept the dealer is.
Since you said you unhooked the battery I agree with the above that it probably needs a throttle body cleaning.