Vacuum gauge at WOT

[ponyboy0123]

So I’ve been made aware that when you’re WOT the vaccum gauge should read 0. I’ve never really paid attention to that gauge but decided to look at it today and noticed that when I’m WOT it’s reading between 1-2inhg, never saw it reach zero though. Does this indicate a possible vacuum leak or is this within normal operation?

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[SheepDog]

The vacuum gauge isn't accurate, and is not actually measuring manifold vacuum. The data is inferred by the PCM from other inputs such as throttle position, RPM, load, etc. It is also effected by altitude.

Check your Fuel trims if you want to look for a vacuum leak

 

[ponyboy0123]

The vacuum gauge isn't accurate, and is not actually measuring manifold vacuum. The data is inferred by the PCM from other inputs such as throttle position, RPM, load, etc. It is also effected by altitude.

Check your Fuel trims if you want to look for a vacuum leak

Appreciate the response, I don’t believe there’s a leak or anything else hindering performance. Cars running great I just didn’t know if there was possibly some power being left on the table considering it wasn’t reaching zero. Makes sense though.

 

[SheepDog]

Yeah, it really is a dumb thing to have. I'd much rather have Oil temperature

 

[Idaho2018GTPremium]

Theoretically the entire intake tract is in a vacuum or negative gauge pressure since there’s dynamic frictional losses through all the intake components even at WOT. So if it doesn’t reach zero that would be normal. It will always be below atmospheric pressure until downstream of combustion where it is obviously positive pressure.

 

[ponyboy0123]

Theoretically the entire intake tract is in a vacuum or negative gauge pressure since there’s dynamic frictional losses through all the intake components even at WOT. So if it doesn’t reach zero that would be normal. It will always be below atmospheric pressure until downstream of combustion where it is obviously positive pressure.

Man thank goodness for people like you who know what they’re talking about hahaha. This makes sense, I appreciate the explanation, I assumed there were multiple factors that went into it but wanted to be sure.

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