''Acoustic Control Induction System'', or ACIS, is an implementation of a
variable-length intake manifold
In internal combustion engines, a variable-length intake manifold (VLIM),variable intake manifold (VIM), or variable intake system (VIS) is an automobile internal combustion engine manifold technology. As the name implies, VLIM/VIM/VIS can vary ...
system designed by
Toyota
is a Japanese Multinational corporation, multinational Automotive industry, automotive manufacturer headquartered in Toyota City, Aichi, Japan. It was founded by Kiichiro Toyoda and incorporated on August 28, 1937. Toyota is the List of manuf ...
.
Simply put, the ACIS system uses a single intake air control valve located in the intake to vary the length of the intake tract in order to optimize power and torque, as well as provide better
fuel efficiency
Fuel efficiency (or fuel economy) is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical energy, chemical potential energy contained in a carrier (fuel) into kinetic energy or Mechanical work, w ...
and reduce intake "roar".
The
engine control unit
An engine control unit (ECU), also called an engine control module (ECM), is a device that controls various subsystems of an internal combustion engine. Systems commonly controlled by an ECU include the fuel injection and ignition systems.
The ...
(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. The valve (or valves in newer models with multiple valves to create more than 2 lengths) is either fully opened or fully closed.
An example of early single-valve ACIS programming would be the 3.0L 3VZ-FE engine. The ECU actuates the VSV to close the valve when the throttle position is 60% or greater and engine speed is 3,900 RPM or more.
Applications:
*
5E-FHE
*
1G-FE (VVT-i)
*
1GR-FE (Single VVT-i variants only)
*
1GZ-FE
*
2JZ-GE
*
7M-GE
*
3S-GE
The Toyota S Series engines are a family of straight-four petrol (or CNG) engines with displacements between 1.8 and 2.2 litres, produced by Toyota Motor Corporation from January 1980 to August 2007. The S series has cast iron engine blocks and al ...
*
1S-iLu
*
1MZ-FE
*
3UR-FE
*
1UZ-FE (VVT-i)
*
3VZ-FE
See also
*
T-VIS Toyota Variable Induction System, or T-VIS, is a variable intake system designed by Toyota to improve the low-end performance of multi-valve engines.
T-VIS is intended to improve the low-end torque of high-performance, four-stroke internal combust ...
External links
Lexus ACIS
References
{{Reflist
Engine technology
Toyota