ACIS question

[celica_xr9145]

I was talking to another celica owners the other day and he was talking about the ACIS and when he hits 5100rpm, the revs build up faster and the noise changes. He said it was quite noticable.

I've taken my car out a few times and cant feel it at all. Ive tried it in 1st to 2nd and 2nd to 3rd.

On closer inspection, i'm missing the screw that you can adjust the butterfly valve angle. I've replaced the screw but don't know what is should be set at. (i'll take a pic).

I know it's not like VTEC or anything but should it be noticable?

It's a gen 2 3SGE by the way.

[Alex B]

You could hear the butterfly open and close on the mr2, it was no where near that high in the rev range when driving though, and no noticeable power difference was felt. If your at idle you can pull the throttle with your finger and you will see it open, might have to give it a few revs to do so.

[sergei]

you might find in his case ACIS is not closing at all hence he feels "kick". The ACIS by default is open unless there is vacuum applied to the diaphragm type actuator. If the diaphragm is poked he will always has "high rpm" mode, which will reduce low rpm torque.

EDIT: I might confused open with closed and high rpm with low rpm, but general idea still applies (I am not sure what is the default position of ACIS, I know for sure TVIS is open, and TVIS is similar system).

[celica_xr9145]

You could hear the butterfly open and close on the mr2, it was no where near that high in the rev range when driving though, and no noticeable power difference was felt. If your at idle you can pull the throttle with your finger and you will see it open, might have to give it a few revs to do so.

Can you remember where about in the rev range you can hear the valve open?

you might find in his case ACIS is not closing at all hence he feels "kick". The ACIS by default is open unless there is vacuum applied to the diaphragm type actuator. If the diaphragm is poked he will always has "high rpm" mode, which will reduce low rpm torque.

EDIT: I might confused open with closed and high rpm with low rpm, but general idea still applies (I am not sure what is the default position of ACIS, I know for sure TVIS is open, and TVIS is similar system).

As far as i know, the valves are supposed to open up in the rev range to open up the chamber.

When you turn the ignition on without starting, the buttlerfly valves close which means the diagphragm works and when i rev (seemed to be dead on 5100rpm), they do open.

Still didnt seem right when i drove it so i removed the air chamber and 2 of the butterfly valves were loose. When i closed the valves, the 2 on the left didnt close properly and when they did close, they got stuck

[celica_xr9145]

just found this youtube video. If you jump to 1:20, mine is just like this, same valves aswell but mine are even more loose

http://www.youtube.com/watch?v=9fYDd94pf98

By the looks of it, its a simple job to sort

[Alex B]

Its load/vac dependent not rev dependent. But quite low, like 3k or so on a normal take off.

[RomanV]

You can hear it if you've got a pod filter quite distinctly, if you've got a standard intake setup then it's not really noticable.

Not really any noticable kick in power IMO.

[Adamal]

Not really any noticable kick in power IMO.

Yep. Just feels like standard power through higher revs

[celica_xr9145]

Just took the top intake chamber off and tightned the centre but so the 2 butterfly valves are tight and dont move around.



I dont know what that screw is for, its better when the screw is out, that way the valves close properly.

Also made sure the vacuum lines are all ok which they were, same with the diagphragm.

Once all back together, took it for a drive and i can hear it now. I find you only feel it when your not giving it full throttle and building your revs up slowly.

It does happen at 5100rpm, gave it full throttle and valves still stay shut until you hit 5100rpm.

Anyway, all sorted, much more smooth and less boggy at lower revs, great improvement!

[Alex B]

Again it’s not rev dependent its vac and load dependent.

[celica_xr9145]

Again it’s not rev dependent its vac and load dependent.

Thats what i used to think, i got someone to rev to exactly 5100rpm and it is when it opens. I also got him to give it full throttle and it stays the same until 5100.

If you look under the intake manifold, there is an actuator with a vacuum tank and a hose going from the actuator to the diaphragm.

It does make sense though, you wouldn't longer runners at low rpm, you'd want short to give you better performance at low rpm and long runners at high rpm?

'...the ecu signal applies a stop signal to the pressure regulator, by cutting off the vacum, and the return spring opens the butterflys into the open position....'

'...It appears that there is an ecu triggered solenoid valve connected to a vacuum operated actuator which is connected to a lickle arm that opens a set of flaps. At approx 5krpm the ecu provides a route to earth for the VSV, it opens and lets the vacuum through, which operates the actuator and flaps the flaps....'

[sergei]

Isn't opposite: shorter pipe having higher resonant frequency?
So long runners for low RPM and short of high. Also works for general volume of plenum. Lower volume will have higher resonant frequency (Helmholtz resonance).

[1I1]

Isn't opposite: shorter pipe having higher resonant frequency?
So long runners for low RPM and short of high. Also works for general volume of plenum. Lower volume will have higher resonant frequency (Helmholtz resonance).

More than likely if it's anything like intake trumpets and exhaust manifold runner lengths where short = top end and long = mid range torque

[celica_xr9145]

thats what im trying to figure out, i've looked at it a few times now.

When the ignition is off with no keys in the ignition, the flaps are open.

As soon as you turn the key, the flaps close.

Start the car and the flaps stay closed, rev it to 5100rpm and the flaps open although sometimes the diaphragm sometimes gets stuck leaving the flaps open.

According to this:

http://youronlinemechanic.com/2007/10/1 ... on-system/

you are correct, i dont understand how opening up the chamber shortens the runner length