I believe my ACIS system isn't working, my car seems to be lacking low end power. I have tried activating it with my techstream with the "intake vsv" command and my launch diagun iv, neither tool showed a movement in the actuator. I can move the actuator by hand and my CEL is not on these tests were done with the engine idling.

I know my engine has been messed with in the past by POs, when I bought it there was dried coolant everywhere and the radiator had been replaced. Upon further research I recently found out through lexus service records that the engine had been overheated and ran poorly with the suggestion that a headgasket was bad. I assume the owner took it to an indy guy and had the headgasket replaced where the guy also misplaced a few bolts that held down the wiring loom and heater pipes. I'm thinking that guy also neglected to install the ACIS hoses correctly but it's a job that will require $50 in gaskets to check so you can see why I'm reluctant to pull the manifold.

I'm going to see what I can do with an inspection camera to look everything over but I don't have a lot of hope. I am also going to try to manually activate the VSV being that the connector is easy to get to on the passenger side of the intake manifold.

 

what does ACIS stand for ?

 

Acoustic Control Induction System, similar to TVIS Toyota Variable Induction System.

 

very interesting, never heard of this before.

 

After doing some troubleshooting tonight I found the VSV or the sub harness going to it must be open, with a multimeter I get no resistance when checking from the connector on the side of the intake manifold. Using an inspection camera I verified that the VSV was connected, no hoses were loose and the connector looked good.

I also tested the functionality of the bidirectional control of the VSV. When controlling "intake vsv 1" I can activate and deactivate the VSV which I substituted with a test light for the test.

I have the ACIS valve closed by using a zip tie on the back of the intake manifold to hold it closed, this is purely a test until the parts I need arrive. Unfortunately this means I have to remove the intake manifold.

 

might as well get your injectors sonically cleaned while having the intake manifold open.

 

I figured this topic would be over the heads of this forum. Keeping the ACIS plate closed (as it would be if my VSV worked) has netted a MPG increase and more low end power. Before I would routinely see from 22 to 23 MPG now I'm seeing mid to high 24 MPG. Keep in mind the ACIS plate should only open above 4700rpm and 60% throttle, any other time the plate is closed forcing the air to take the longer runners in the intake manifold.

I bought an entire intake manifold with every part from the ACIS just incase I run into more than just the VSV, turns out that VSV is open as well. Seems like with age and heat these VSVs fail, mine isn't just a fluke.

 

I finally made myself remove the intake manifold and replace the VSV. Low rpm power is better definitely a noticable improvement. Cartunenz made a video about this a while back for those who care to watch.