High vacuum.

[Howling Mad]

My car normally runs about 18 in of vacuum but will driving today it dropped to 30 on the gauge, power logger showed 34. Any ideas?

 

[Chuck Leeper]

MAP sensor STB??

 

[Howling Mad]

STB?

 

[No disintegrations]

Wonky gauge, 34 in hg impossible on planet Earth.

 

[salvageV6]

S^it The Bed.

You have to be fluent in Leeper to understand him sometimes.

 

[Chuck Leeper]

S^it The Bed.

You have to be fluent in Leeper to understand him sometimes.

 

[Chuck Leeper]

Wonky gauge, 34 in hg impossible on planet Earth.

The PL uses a Map signal.

 

[NY Twin Turbo]

Could it be the map sensor just lost power or ground? Cut / loose wire, plug, bad connection? Something like this?

 

[dank GN]

On the page where you can load tunes and logs you can adjust the offsets of the map sensors aswell as anyother sensor hooked up . What sensor are you using ? I’m curious about the limits in vacuum of a stock style 3 bar . Because if it can read 3bar of Boost which I believe is 30ish does that mean it reads 30 hg of vacuum aswell ?

 

[earlbrown]

I doubt it. I've never taken apart a GM MAP, but there's no rule that says atmospheric has to be in the middle of the range. Then again 99% of GM cars that use a MAP sensor never see boost, so the highest they can read is just shy of atmospheric.

1 Bar is a little over 14PSI, so 3bars is 43.5 pounds of boost.

An inch is right at 1/2 a pound (that's why the FP only drops a few pounds when you reconnect the vac line at idle)

 

[Jerryl]

Sounds like you may have a 2 bar MAP with a 3 bar selection on PL?
Make sure the MAP selection is correct on the PL console, and go from there.

 

[Howling Mad]

It's a 3 bar map, I was thinking maybe a voltage issue, it did it yesterday when the car was hot, but not since?