low vac at idle

[93talontsifwd]

Okay heres the problems I am having the car idles like crap getting only about 12 in hg manifold vacuum. Also I did a log and got 100% st long term fuel trims and .03v cycling to .05v for o2 sensor all other senors are getting great readings and recently did tune up plugs,wires,pcv,filter. Did compression test 75 on first puff then 150 across the board. Checked all sensors with vantage oscilloscope they work fine and cleaned the egr its not stuck closed and works properly. I do hear a leak at the top of the tb but I have sprayed and sprayed at it but no idle up so I dont know if that is just air passing through or what and did a propane test for leaks no idle up. Also took off all the vacuum hoses on the tb and plugged them one by one no change. Also when you give it throttle it runs great with 19 in of mercury at the manifold this problem is just at idle. Only mods so far is external dump on 2g o2 housing which was homemade got it for free and K@N air filter. Recently had the ecu checked out it had bad idle driver circuit put it in and car still runs bad. Could I be off a tooth still even if the car runs good off of idle. Any help is apreciated thanks.

 

[Defiant]

First, make sure your gauge is hooked up properly, with no kinked lines.

Then, get a test gauge, and see if that helps:

http://www.iwemalpg.com/Vacuum_gauge.htm

 

[93talontsifwd]

we where using a snap-on vacuum gauge

 

[Defiant]

Tapped into where?

 

[93talontsifwd]

the pcv vacuum source