power gains with ACIS unplugged

[SRZMK3]

ok let me tell you something ive noticed on my butt dyno....:3d_frown:

when i have my ACIS vacuum line in the correct spot, (i have checked my vacuum routing a million times i swear) my car loses power at 4k and then gains a tiny bit back at 5k going thru 6k... and whne i have the vacuum line unplugged and hanging free my car has a monster powerband that just takes the :: angry :: hell off at 4k all the way to 6k WTF!!! :icon_evil isnt acis supposed to help? is my car just broken and thats a way to tell?:aigo:

 

[bioskyline]

weird indeed. can you move the aics linkange manually?

 

[SRZMK3]

yeah but it snaps back into shut position like it should...

 

[bioskyline]

ok though the linkange is sticking and not working proper. i dunno that valve when closed seperates the intake and when open it allows air all the way thru. unless from the pcv vent over time, like the one i took apart, is just so full of sledge on the inside its not flowing proper.

 

[SRZMK3]

possibly? could it be because my IACV and TPS are not working porperly?

 

[bioskyline]

yes. the tps may not be telling it to not to activate and the ecu is expecting it. dont think the iacv has to deal with it. or the butterfly has to much gunk and not closing all the way. you can remove the 6 screws on top of the intake, remove the plate and look inside. you can also hook up a vac line and using a vac pump, or just plain suck on it see how it moves.

The engine control unit (ECU) controls the position of one or more air control valves based on input signals from throttle angle and engine RPM. The vacuum switching valve (VSV) which controls the vacuum supply to the actuator is normally closed and passes vacuum to the actuator when it is energized by the ECU. By energizing the VSV vacuum is passed to the actuator, closing the air control valve. This effectively lengthens the intake manifold run. By de-energizing the VSV, vacuum to the actuator is blocked and trapped vacuum is bled off of the actuator diaphragm. Toyota ACIS is an On/Off system.

 

[SRZMK3]

lmao... you know... mabey i just need a new vacuum line

 

[Nick M]

The engine control unit (ECU) controls the position of one or more air control valves based on input signals from throttle angle and engine RPM. The vacuum switching valve (VSV) which controls the vacuum supply to the actuator is normally closed and passes vacuum to the actuator when it is energized by the ECU. By energizing the VSV vacuum is passed to the actuator, closing the air control valve. This effectively lengthens the intake manifold run. By de-energizing the VSV, vacuum to the actuator is blocked and trapped vacuum is bled off of the actuator diaphragm. Toyota ACIS is an On/Off system.

Your copy and paste is appreciated because it is accurate, but that(more than one valve) is the description for the later cars and not ours.

What the OP is describing is impossible to do with the system. We have one valve inside the plenum, and the default position is open. With a manlfunction, you will have too large a plenum to create high air velocity at low rpm for hard acceleration. The valve closes with switched vacuum to make a smaller plenum and faster air charge. If your car starts bogging down as it gets to 4000 rpm, then you have a different problem. I wonder if you have the lines in the right spot. The canister has a one way function. I wonder if it is passing straight through, so you always have vacuum on it. I am going to have to look at the repair manual, it has been a long time since I thought about routing.

I scanned the ACIS page once. It should be online at autoshop101. Since bio gave you an overview of the VSV control operation, this is why. This is a really old scan. Poor quality by todays standards.

 

[Nick M]

Here you go.

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=EM&P=50

 

[SRZMK3]

wow thanks this is exactly what i needed to find!! but.. it still doesnt make sense why when i unplug it my car is faster from 3500 all the way to 6000... i wonder if its something completley different from acis like mabey its a tps problem or something else..?

 

[Nick M]

wow thanks this is exactly what i needed to find!! but.. it still doesnt make sense why when i unplug it my car is faster from 3500 all the way to 6000... i wonder if its something completley different from acis like mabey its a tps problem or something else..?

Horsepower increases with rpm. Provided you don't have a large drop in rotating force (torque).

If you unplug it, there isn't vacuum on the valve, and it opens all the way. By design. In the opening post, you said you lost power up high.

 

[SRZMK3]

re evaluating... when its plugged in, i lose (k im talking butt dyno) power like its seriously throwing me forward kinda thing from 4k to 4.8 then at 5 it barley comes back. when i unplug it (the vacuum line to the ACIS diaphragm and a bolt stopper on the vacuum line) there is no loss and it actually accelerates faster through the top end 4k to 6.5k, actually puts me in the seat.

 

[CT26smoker]

Funny thing is, on the Cressida, that is more of an old lady's car, they don't have the ACIS system......
They have an intake manifold like the 7MGTE.
Go figure :aigo:

 

[SRZMK3]

yeah... i wonder why they put that Y pipe on the supra 7mge