Throat Yogurt
Seasoned Member
- Joined
- Oct 7, 2021
- Messages
- 1,528
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- V-Series Cadillac(s)?
- 2022 CT4-V Blackwing N0460548
Correct. Millimeters of mercury is the metric unit of vacuum (inches of mercury is imperial), so all boost gauges read that way when the engine is not in boost. Measuring vacuum is a good diagnostic way of looking for leaks.It's the dif between 'boost' and 'vacuum' and GM isn't the only manufacturer that displays it this way as that's what hg indicates, instead of converting it to some -psi value.
I think it's more obvious as such when off boost cause you have more time to look around, as opposed to being on boost when you're caning it and should be eyes up.