vacuum question.

[eric95]

when i start my car up, i get around -14 vacuum, after 20 minutes of driving, it's -19.

i replaced every hose there is to replace.

i did a search already, but no one elses vacuum changes after driving. they either have low that stays low, or high that stays high.

anyone see this b4?

 

[WhiteTsiAwd]

This is not a problem. It is because when you first start up your car, your car has to warm up so it has a high idle until it gets warm. As your car gets warmer the lower the idle goes, which the lower the vacuum goes. Its also RPM related.

Try this, when your car gets all the way warmed up, free rev it until you get to the RPM's that it was at when you first started it. Your vacuum will be the same.