Jcinstalls
New member
Ive installed a permanent vacuum gauge and I'm a little worried and confused about what it reads. My elevation is 6,800 ft above sea level and its just a cheesy gauge that is connected to a empty port on the manifold. I have an aftermarket intake and have done things like gasket port matching, a bigger TB from a 3400, and an new manifold back exhaust with a cat/res delete and a strait threw muffler. Also the motor has a new fuel regulator, IAC, purge valve, egr valve, map, maf, And pcv. At idle it will read 12 inches of vacuum stead(which is low for my elevation i think). Acceleration at half throttle will be about 5 inches. At wot it will read 0 inches which makes sense because the TB is open to the air and its natualy aspirated. But what i don't get is why it reads 0 when cruising at highway speeds 2/3 ish throttle 65-75mph. The only vacuum leak i could possibly have is the LIM because ive fixed all the old tubes. Ive spent alot of time learning about manifold vacuum and cant figure out why it all reads so low all around. Has anybody had the same reading? Or is there something wrong? Also i feel like im getting bad mileage, could it be from the low vacuum on the fuel pressure regulator?