boost/vacuum prob

[Mephisto]

once again ive researched the archives and didnt quite find the answer i was lookin for.

quite a weird problem im having here. none of this started till i messed with the brake booster hose. when i give the truck gas it accelerates normally, but once i get into boost, it feels like the acceleration has been cut in half, and the vacuum line thats right near the gas pedal on the lower heater vent pops off and starts hissing very loud. i went on a datamaster run and noticed that at WOT im only getting 10lbs of boost, and that my vacuum levels have dropped from a normal 70-80Kpg with TPS at 0% to a low of 37Kpg with TPS at 0%. then just for the hell of it, i set my ultimate to the T1-20 setting and went for a run. and my boost went to 15.2 at WOT, but no change in vacuum Kpg.

could this be a bad brake booster check valve? ive checked all vacuum lines and they appear to be fine. maybe something to do with the HVAC??

also, i tried to find that diagram of the vacuum lines that someone had posted a lil while back, but i couldnt find it. ::bill lumberg voice:: if someone could go ahead and post that... thatd be great... uhhh yeah....

 

[Falco]

Howdy,

I'd say that your HVAC sees boost. This could be because a wrong check valve. Could be a check valve installed backward. Have you played with the two check valves around the HVAC connection lately?

You should be able to find a vacuum diagram on your radiator support under the hood, but here is an other one. The EGR is deleted on that one, but it could help.

http://www.usionline.net/hpm/1993 Typhoon/103000/pages/103000 Vac diagram.htm

HTH,

 

[Mephisto]

well i finally got around to replacing all my check valves today, the HVAC check valve was broken, but the problem still continues. now when i get the truck in boost the hose still pops off the lil heater thing, and when i let off the gas i hear a loud hiss just like a blow off valve.

anymore theories on WTF is goin on?