So I have my car running great, or atleast great in my mind. I'm in the middle of attempting to burn my first chip. I have over 16 different data logs around 10 minutes each. BUT, back in the garage I see my fp guage is at 40psi at idle with vacuum attached and FMU on an independent vaccuum source and the needle dialed in all the way (richer not leaner). I remove the vaccum off the afpr and the fricken psi jumps to 50!! I put the vaccuum back on the psi goes back to 40. This is backwards from what I now? Any advice is greatly appreciated.

 

Thats normal. When you open the throttle on the engine, it allows more air in freely, which creates LESS engine vacuum. You'll get more "vacuum" by sucking through a 1/16" straw than a 1" straw... Only times you will see higher vacuum above idle are, say, when your rpms are high and then you release the throttle...creates more vacuum because the engines demand is greater, but the throttle is in the idle position, creating a greater 'suction'.

As you approach WOT, the engine produces less and less vacuum, until it basically reaches atmospheric at wide open (zero vacuum, zero boost)... That's why when you pull the vacuum line from the regulator, fuel pressure shoots up. It's simulating wide open throttle.