Why am I getting vacuume?

[snooze]

OK, I am trying to install a boost gauge...First I ran it off the fuel pressure solenoid (one with blue line) and when I rev the engine it shows 20 vacuume?! then drops to 15 vacuume...ok...I'm a little confused by this so I connect it to the hose that runs to the TB marked "P"...but I get the same type of reading. Is this the reading I am supposed to be getting? am I doing some thing wrong? I have looked at the VFAQ's and from what it looks like I am doing the right thing...but what do I know

Thanks for any help

 

[crankbender]

when the throttle is at a low setting the tb restricts the air comming in and creates a vacume behind it. a new engine should have around 18" hg vacume when at a warm curb idle.

 

[snooze]

But when it is at idle the guage is at 0 PSI, it's only when I rev the engine to 5.5k that it goes spikes 20 vacuume then drops to 15 vacuume.

But now I just tried moving the wastegate arm and it doesnt want to budge, if the wastegate is stuck open will this cause the guage to read as a vacuume?

 

[snooze]

I found some boost, the turbo will build only 5 psi ( @ 5.5k RPM) of boost then immediatly begin to loose pressure, the wastegate actuator arm will not budge when I try to move it by hand (flapper stuck open), so tomorrow I will see if I can get it lubed up and get it to move again.

I'm 99% sure this is my problem...man if its only working at half power full power is going to be awesome

 

[crankbender]

Are you driving when this is happening or are you sitting still in neutral?

 

[RocketDSM]

You're car SHOULD pull some vacuum until you are revving the engine with a load on it (like driving). Revving it sitting still will do nothing for you. I'm not sure about the spike thing. I actually have the opposite happening to my car. It idles with about 13"Hg vacuum and when I start revving it, it jumps to 0-5Hg and back down to 18-22Hg. I'm looking into it.

 

[snooze]

Doh, I have just been reving the engine in neutral *smack's forehead*

Ok, but the actuator arm was sticking after all, when arm would go to open it would get stuck and not go back closed on its own, so I took out radiator/fan (I needed to change my fluid anyway) and removed the actuator => lubed the arm and then bent it inward, seems to solve the problem...but now I will reinstall the boost guage and DRIVE it this time and see what happens.

Thanks for the help guys

 

[crankbender]

rocket- when you say it drops down to 18-22" do you mean it stays there or does it go back to 13" when the idle settles. If this is what happens it is because the engine will pull more vacume as the rpms wind down. It is still trying to suck past the closed TB and with more RPMs it is able to pull more air. As for the 13" vacume you either have cams on the car or a problem. If you don't have cams then you should first do a compression test to make sure the engine is healthy. While you are in there messing around check all the vacume lines to see if they have a leak. Does the car idle really high? is it lopy? how are the air/fuel mixtures reading? I believe the factory spec on idle vacume is 18" for a 1g with 8.5:1 compression. It should be higher on a 2g. If you need some more direction let me know i just got done rebuilding most of the intake piping on my car because of an idle stall problem...which i hope is fixed now.