I installed the NGK iridium 1 step colder plugs and my engine seems to be running rougher (Check my sig for mods). On the other hand the car seems to be pulling better and there is more growl to the engine tone. I also noticed that I hit 8psi on the dot and before I was only hitting about 7.5...maybe I had a little leak that was fixed when reinstalling the throttle body piping.

Is the rougher idle due to the 1 step colder? should I be concerned?

edit: maybe rough idle is not the best way to describe it... The AFR and RPMs seem to be consistent but the engine is kinda shaking at low RPMs

 

gap?

 

i did not change the gap so however they came. From what i understand the LFR6AIX-11 are properly gapped from the factory.

 

Maybe the ecu just needs to relearn the idle.

 

after driving the car this morning I noticed it happens after the car warms up. When I am cruising at 3k RPMs there is a somewhat faint woom...woom...woom noise (sorry thats the best way I can describe it)

 

LOL I figured out what the problem was... I tightened the strut bar to much and it was rubbing on the plenum and thus causing a vibration/grinding noise. Guess I was so paranoid I did something wrong I failed look for the obvious. Anyway I'm glad I found it and that it was an easy fix

 

do you have a spacer or upgraded plenum? i fail to see how a stock strut bar can be tightened down so much it's touch a stock plenum...

 

Glad you figured it out, 1step colder iridium plugs at stock gap should not cause any idle issues.

 

i have a spacer. check my sig.