DubFamily
Veteran Member
AMP = Absolute Manifold Pressure, not MAP. That's what he was talking about.Yeah, I know what a MAP sensor is. MAP, not AMP. Instead of working out a formula, try this. Engine off, look at the reading. That will be your reference point, atmospheric. Then engine on, look at the reading.
What I was getting at is where that sensor is, somewhere in the intake manifold, may not 100% reflect the pressure in that charge air pipe.
There is no possibility of their being a vacuum in the manifold at idle, and pressure in the connected piping from the intercooler. "Nature abhors a vacuum" is quite true; if the manifold were at vacuum and the pipes were not, they would equalize instantly and no vacuum.
And I see a very slight vacuum on my car at idle as well; just FYI.