I have a minor vacum / boost leak somewhere in my system. My car is all stock. It has a rough idle, and max boost is 7 psi. Not sure where to start.

 

OK, few things here.

First, it may not be a vacuum leak. A vacuum leak between the throttle body and the motor will raise the idle up, but it will still be pretty smooth. A vacuum leak between the throttle body and the turbos won't effect idle at all, but you can lose boost through the leak, making for a loss of power.

Hate to say it, but one thing to check is a compression test. A bad motor will have a rough idle and oftentimes be hard to start, especially when the motor is warm.

Another easy possibility is spark plugs - if the spark plugs are old and fouled, that will greatly drop power and will roughen the idle up.

Dale

 

The car isn't hard to start. I will do the plugs this weekend and see if that helps. Not sure how that would affect boost though, but I will give it a shot.

 

is it rough when accelerating to 7psi?

like dale said, i had a spark related issue. My plug wire was arcing. The thing was, i idled rough, accelerated poorly and as a result couldnt generate boost. But the key symptom being acceleration was rough like idle.

EDIT: can you hear any boost leaks in the engine bay? out of curiousity? i had a solenoid shatter and again like dale said, my idle was elevated but smooth. I couldnt get past 7ish psi to save my life. it was a second turbo control thing.