hey guys I am getting misfires in cylinders 7 and 2 and I have changed about everthing i can think of but they aren't going away. I checked the plugs, wires and even the coils and i am still getting a lot of misfires. The truck runs great is the wierd thing. It feels like it may being missing a little when it first starts but after it warms up it idles fine. I don't understand it. Anybody have any ideas?

 

LS1 edit and desensitive them or do like I did and toally get rid of them...unless ur spraying, then just desensitze them...

 

I had the same problem, and changed everything just as you have. I found out that my gasket between the intake manifold and heads was torn. I replaced it and the problem was gone. Try that or GM top engine cleaner. Any GM dealership can do it for about $75.00. Ensure that they do the GM top engine clean and nothing else.

 

alright i will have to try that. Which of your cylinders were missing when you had to change your gaseket. That sounds logical to me because sometimes i get codes in other cylinders too but just minor ones.

 

My missfire was on 1 & 8. There were little ones on other cylinders as well. After doing GM top cleaner and changing intake gasket all was good. Except my idle...... but when you fix something on a LS1, something else seems to go wrong..... Good luck.

 

Have you checked you PR lately. When my valve spring went to **** I started getting a whole bunch of misfires on a few cylinders

 

i don't know what you mean by pr?

 

should i do the top cleaner first or check my intake gasket?