Boost gauge oscillation....normal?
#1
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Boost gauge oscillation....normal?
Here's the deal. Have a mechanical Autometer vacuum/boost gauge hooked to an intake vacuum line for my STS turbo. Under load and under positive boost.....gauge is rock steady.
Under VACUUM the gauge sometimes oscillates; usually when at 20 inches of vacuum or more. I notice it most when idling or coasting with my foot off the gas. When applying load to the car (i.e. pressing the throttle) I don't see an oscillation.
So, is this normal, or a symptom of some other problem?
It's annoying at times if nothing else. I monitor the gauges like a hawk with this FI.....so input is appreciated.
Thanks.
Under VACUUM the gauge sometimes oscillates; usually when at 20 inches of vacuum or more. I notice it most when idling or coasting with my foot off the gas. When applying load to the car (i.e. pressing the throttle) I don't see an oscillation.
So, is this normal, or a symptom of some other problem?
It's annoying at times if nothing else. I monitor the gauges like a hawk with this FI.....so input is appreciated.
Thanks.
#4
TECH Fanatic
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A long time ago, a vacuum gauge was used to diagnose engine problems. A fluttering vacuum at idle could indicate a misfiring cylinder, sticking valves, etc.
You are probably just seeing a little reversion in the intake from the cam. Which goes away when you have the throttle opened a little and more air flowing through the intake.
You are probably just seeing a little reversion in the intake from the cam. Which goes away when you have the throttle opened a little and more air flowing through the intake.