So I got a b18c1 gsr swap on my 99ek and i’ve been having some terrible idle issues. Idk if it’s a vacuum leak or what but I’m guessing it is. On cold starts my idle is high at 2500 - 3000 and then when it gets warm the idle would bounce between 2 and 2700. Then when I turn on the AC it lowers the idle bounce to 1500 to 2500.(BTW i have a skunk2 intake mani) and I replaced the IACV with a new one and changed the gaskets on the TB and intake but idle still the same. So help me out some ideas y’all.

 

Has this all started when you finished the swap or did this recently start?

What manifold do you have the SK2 Pro series or ultra?

Sounds like you have a big vacuum leak or the IACV is stuck open or not the right plug for the IACV.

Any check engine codes?