Thread: Am i missing something?

There's a module in front to the boost bypass valve that has a vacuum line running to it from the boost bypass. Just above where that hose attaches is another hose nipple that is empty. Should that have a hose attached?

Reason I am poking around is I am getting a surge in rpm when I am at low rpm and accelerate slowly. The rpms and boost gauge will bounce up and down. If I open the throttle enough to downshift the car accelerates fine. It is fine at wot... this is not a fuel delivery issue. Something to do with vacuum. Thoughts?

No, that is a vent.

Thoughts are a vacuum leak.

Check all the lines.

I did check the lines. Nothing off or rotted out.

While connected it may have stretched over the years and leakes in a little air. Best test is to take some Carb Cleaner Spray and spray each connection point to every vacuum line. Go slow, 1 by 1 and if the RPMs surge up, you have a loose fitting and its leaking there.

^ This. Also where my saying to spray every connection to see if the motor revs up come into play. The slightest crack or looseness can throw off the trims enough to cause problems.

So for an unrelated thing I reset the pcm. The surge went away for a few hours and has slowly come back.

Fuel trims.

What do they say?

You've got a way to scan it via a live feed scanner? Bet they're pegged @ 16.4