Intake Plenum Valve,89 N/A

[mrnickleye]

Seeking more info on the valve. Its located in the intake plenum, and the vacuum motor that operates it can be seen looking down past the cold start injector between the 2 runners that attach to the plenum. It actuates at high RPM, controlled by the ECU turning on a VSV. When the valve closes, the plenum chamber is seperated into 2 sections, and the horsepower feels increased. APPARENTLY..this is due to 'shortening' the intake runners. Today I am going to apply full-time vacuum to the actuator and close the valve during all RPMs, to see if there is any HP gains. Has anyone done this?? What happened?? I am looking for more bottom end torque, under 4000RPMs.

[ahmedootie]

hey man let us know if it works out or not! i think its obvious no one here's tried it, otherwise they probably woulda responded already, so u b tha first

[albertmdh]

all im thinking is if something doesnt work that way in the first place, maybe its not supposed to...

[Jeeves]

Are you sure this is on a Supra? That's technically called the ACIS Valve (IIRC) and I know my Camry (Daily Driver) has one, but I don't think the Mk3's did.

[mrnickleye]

Yep, 89 NA, Federal Car (maybe different than Calif. car ?) The valve is inside the 'Intake Chamber' (what Mitchell Manual calls it). With the vacuum applied full time, it 'feels' like a bit more power off the bottom after 2k rpm. I'll run it around like this for awhile, then back to normal, then on again to see if their 'really' is any gain. The only drawback I can figure is , full time vacuum may wear the diaphram out prematurely.

[mrnickleye]

Here is a quote from a review on the '89 turbo ( "For the turbocharged version, compression was reduced to an aprrox. 8:4:1 ( I got this spec on the net, so I don't know how accurate it is). And the ACIS (automatic control induction system) was dropped". ..http://www.epinions.com/content_48377335428
Another forum site person said all Toyota DOHC motors had this ACIS, (??)...
Soooo, I'll experiment and report back the results.

[mrnickleye]

Originally Posted by albertmdh

all im thinking is if something doesnt work that way in the first place, maybe its not supposed to...

Yep...modify to fly !!!!!

[Ne0z31]

it was not able to be taken out in the camry so i doubt it can be in the supra... it would mess things up or something, although you can sand and modify it to let more air in when it is actually open although i dont think u can get to where u need to get to on a supra like u can on the camry

[mrnickleye]

Quote from Silver Streak: "OK I finally read through all the posts here. This is what I know about ACIS for the 3VZ-FE. I found some old info after researching this a few years ago.

The air control valve opens or closes depending on two variables: engine RPMs and throttle position.

Under 60 degrees for the TP angle, the air valve is ALWAY open, regardless of engine speed. It is also open when the TP angle is greater than 60 degrees and over ~3900 rpm (mine was a bit lower as you can see from the dyno graph).

The only time in which the air control valve is closed is over 60 degrees and from 0 to ~3900 rpm. This is what gives you the higher torque at low rpm. The longer intake manifold (valve closed, VSV on) helps low rpm torque, shorter intake manifold (valve open, VSV off) helps the torque/hp at higher rpm.

Obviously this is all initially activated by the ECU...you can even monitor the ECU command to the VSV. If you really wanted to have this activated at a lower RPM, you can have the air valve open earlier by sending a signal to the VSV, but only if it's over 60 degrees...I guess you could measure the voltage (that represents 60 degrees volts) coming outta the TPS and as well, watch the engine RPMs at 3500 and then open up the valve. Doesn't sound like fun.

After all this, I think just smoothing out these edges on the hole would help out (unless it created more turbulence), anything that smoothes the air flow in the intake should help increase power....