I have a 2006 with a 2.4lt auto and I went to install a vacuum gauge.
i found two vacuum lines to test, evap and brake booster. I’d read that the break booster line isn’t an accurate vacuum reading so I T’d into the evap line running from just behind the intake to the right side of compartment into the evap solenoid. It was steady vacuum at first but then needle started flickering with the ping of the injectors, I pulled the line off of the gauge and could hear the “tick tick tick tick” in sequence with the injectors.

Any help on on a way to fix this problem so it’s a stable vacuum or another location to tap into would be great.

 

Just curious. What vacuum reading is good for?

 

There’s a vacuum port on the intake manifold

 

I’m thinking the vacuum gauge is to monitor engine performance and fuel economy

https://www.google.ca/search?q=using...OJvbiADg_1:477

 

The reason NOT to use the brake booster hose is you could lose your brakes and break something if the tee leaks. There is a check valve, so no worry about back pressure, but when you step on the pedal it might vary.

The reason the "vac" line from the EVAP purge valve won't work is that the valve is a PWM valve, meaning that it opens and closes in a variable manner. It is not really a vacuum source it is sucking fumes from the gas tank and goes into the carburetor, not the manifold.

 

Carburetor?

 

"normally aspirated" EFI?

Yeah, throttle body, which makes it sound worse; the butterfly would be changing the vac pressure all the time.

 

Correct vacuum should be taken from after the throttle body