After my dyno tune at which we took my B16a to 9,500rpm a couple times (built head), I don't get any vacuum at idle anymore. Used to idle at 288mbar, and now it fluctuates between 400-600mbar. And then after it warms up, it will dive even below what it used to idle at, and then shoot up to 700mbar with the throttle closed. Makes it damn near impossible to drive.

I checked for vacuum leaks by spraying brake cleaner around intake manifold and all vacuum lines. No surge in rpm. I also checked all the manifold bolts, throttle body bolts, IAT sensor screws. All were tight.

I moved the cam gears at the tune, but nothing crazy. +4 intake -3 exhaust.

 

Complete a compression & leak down test :-)

 

Damn you and your logic.

Will do. I'm just expecting the worst so I figured I'd ask.

 

massive vacuum leak / blown throttlebody gasket / blown IM gasket / fouled plugs

(little less severe)