Generation III Internal Engine - Vacuum port on rear of manifold not plugged




livewire0201
05-07-2012, 10:54 PM
Just recently finished with the LS1 to LS6 pcv system in anticipation of more mods in the future. This is on a 98 LS1.

When I had the intake manifold off, on the rear there are two vacuum ports, one small, one large, and the map sensor. I noticed that I did not have the rear port capped. I've had this motor swap done in 2006 and 4500 miles on the car, all without this port being capped. There's a possibility it was capped long ago and got "lost" after the tranny swap. Only a few hundred miles since the swap.

After finishing up the PCV job I capped the port. This obviously made it idle lower, however, at WOT it becomes a dog. Driving around town fine, but as soon as I really get on it, theres hesitation and feels terrible. Do I need to keep it capped and run it until the PCM relearns?

Anybody know whats going on?

http://i6.photobucket.com/albums/y203/livewire0201/IMAG0293.jpg


DONAIMIAN
05-08-2012, 10:58 AM
I would check into getting it retuned. Being something small, its a good chance it wasn't there to begin with during the initial tune.

livewire0201
05-08-2012, 12:31 PM
As far as I'm concerned its never been tuned. Since I've had the motor anyways. Its a bone stock 98 ls1 I picked up in 2002. Obviously the port needs to be plugged. Does the PCM need time to "relearn" it now that there is no unfiltered air coming in? Or do I need to tune it??