i just installed ngk iridium IX spark plugs (Part #LFR5AIX-11) and now im getting a rough idle. i checked the hoses to make sure there were no leaks because i took off the plenum so it would make it easier to install the plugs. any other ideas why the car has a rough idle? thanks.

 

i'm pretty sure it has something to do with the plenum.

 

hmmm...il check that. any other suggestions?

 

make sure all of your bolts on your plenum is tight but don't over tight or you will strip it. It's VERY easy to do so on those bolts.

 

make sure all of the coils are plugged in securely, if you get a connector all the way on, you could have that problem as well.

 

a wrench left inside the plenum? j/k


maybe a vacuum hose you forgot to connect? <<< it happened to my car when I installed my plenum spacer...

 

Stupid question, but did you gap the plugs correctly? Or did you just install them straight out of the package.

 

those NGK comes pre-gapped.

 

I dont think thats a stupid question at all. I think many people have put spark plugs in and never checked the gap.

I would think to check over all your hoses as well.

 

Ok, sorry. I had to ask, because I've made a similar mistake before...

 

yeah, it's a good question. I still check it before installation with those little gap coins.

 

i don't mean to hijack the thread or anything but what is the gap size for our cars, so for my future reference.