[Neal_gn]

I got a 2006 Colorado 3.5L I5, it’s got 183k miles, I replaced the spark plugs and mass airflow sensor today. I did the MAF first and started it after and it ran fine, but after I put the new plugs in, it started misfiring real bad. So I pulled them back out, double checked them and the coil packs, and everything looked fine. I put it all back and and started it, and it was still missing pretty bad. I took all the plugs out and put the old ones back in, and it still was missing bad, (it ran smoothly before) I need help. Cheap fixes if possible.

 

[cart7881]

Welcome to the Nation.

While it could be a number of things, most likely it's going to be something you did while replacing the plugs. Probably related to the coils. Did you disconnect the coils when you removed them? Maybe the connectors could have been swapped?

Find someone with a scan tool that can tell you which cylinders are not firing.

 

[Rex Kramer]

My guess is a bad coil. Start up the truck, unplug 1 coil at a time, you'll know right away if that coil is working. Work your way down the line until you pull one and nothing changes, that's your bad one.

 

[goodc4868]

Njnnj


Sent from my iPhone using Tapatalk

 

[n9cv]

Did you by chance use anti-seize on the threads of the plugs. If so it does not take much to short one out? If not, then did you get any oil or dirt on the tip of one of them? If in doubt, pull two at a time and clean them. OR temporarily put an old back and see what happens. If you have a bead blaster clean them that way.

Obviously a scan tool suggested previously is a much quicker way to find the bad one(s).