Idle control valve issue

[superexpy]

I have been chasing down a suspected vacuum leak for awhile now. There is no check engine light but at light throttle or at idle it is noticeable. I took my throttle body and plenum off my motor to clean and inspect. I saw no issues in tell I blew through the vac port with the big line for the idle control valve and I plugged the other end with my finger and was able to easily blow. I was also able to suck. The leak is at the weird cap thing on the idle control valve itself. Is this sopost to do that or did I find my problem?

 

[toms89]

I have been chasing down a suspected vacuum leak for awhile now. There is no check engine light but at light throttle or at idle it is noticeable. I took my throttle body and plenum off my motor to clean and inspect. I saw no issues in tell I blew through the vac port with the big line for the idle control valve and I plugged the other end with my finger and was able to easily blow. I was also able to suck. The leak is at the weird cap thing on the idle control valve itself. Is this sopost to do that or did I find my problem?

I would say you found your problem. It is supposed to be a sealed system so only metered air enters the engine.

That's interesting though as I would have never suspected it could be a source of a vacuum leak. Maybe with boost ahead of the throttle body it put additional stress on the seal?! But I as well as many others have run centi blowers with no known issues with it.

Maybe that's why my stang did not idle so well.....

 

[superexpy]

I would say you found your problem. It is supposed to be a sealed system so only metered air enters the engine.

That's interesting though as I would have never suspected it could be a source of a vacuum leak. Maybe with boost ahead of the throttle body it put additional stress on the seal?! But I as well as many others have run centi blowers with no known issues with it.

Maybe that's why my stang did not idle so well.....

I sealed it so well see what it does. My idle control valve is the stock one that came on the truck with 10 years of boost