I just installed my alta catch can but something strange came up, it seems the car is running slightly higher boost than before!

when idle, the car sits at 0.5 vaccum not 0.8 vaccum which has been running it for awhile.. there seems to also be some twitch in the boost gauge... any amount of flooring results in the boost running somewhere close to 0.7 bar, which before during normal acceleration the car barely reaches 0, at 120 km (about 70 mph) it's running at about 0.2 vaccum, which before it was more like 0.4 0.5, mileage dropped off almost too significantly, although i got nothing but the fuel gauge to determine that

any theories? i had a minor problem when i installed the ic so it might have something to do with the ic not being put on properly

any help is greatly appreciated

 

bump

 

im sure someone here can answer my question at least

what boost are you guys running on 15%s, with or without catch can!

and btw, i do know this may have nothing to do with each other, but that's what im seeing

 

I'm assuming you have a mechanical gauge that has boost and vac. and not an electronic gauge w/ just boost? If that's the case, it almost sounds like the boost gauge is not hooked up to the correct vacuum line. If you tap the larger vacuum line that runs directly under the intercooler on top of the supercharger, you won't get boost, only vacuum. There is another small 1/8 vacuum line attached to bottom of the fuel pres. regulator on the supercharger. Hooking up to this will give both boost and vac. (On my gauge, vac. reads about 17 at idle and I've hit about 10-11 lbs. boost with the pedal to the floor at about 6k rpm. I have the stock pulley.) Everything should work fine with the alta can installed.

 

i got electrical gauge w/ boost and vac, i tapped off the line running below the ic, it had boost and vac, before more normal readings seems to be about less than what i have now, although crusing seems fine, its when i floor it it twitches and changes

 

hmmm.... Are you sure it's an electronic gauge and not mechanical? The only reason I ask is that all electronic gauges I've seen only display boost and they use a special sending unit. The mechanical ones run directly off a vacuum line that goes from the engine to the gauge so you get boost and vac. When I installed mine I first tapped the wrong vacuum line (The 1/4 in. line directly on top of the supercharger, under the intercooler.) I had vacuum press., no boost, and gauge needle would flutter off and on.) When flooring the pedal, the gauge would barely reach 0. So, I hooked up to the small line under the fuel press regulator and it fixed the problem.