Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Circuit Description
HINT:
- The 1MZ-FE engine has 2 VSVs No. 1 and No. 2)
- The 3MZ-FE engine has a VSV No. 1 only)
ACIS stands for "Acoustic Control Induction System".
1MZ-FE:
This circuit opens and closes the Intake Air Control (IAC) valve No. 1 and No. 2 in response to the engine load in order to increase the intake efficiency.
When the engine speed is 4,100 RPM or less and the throttle valve opening angle is 30° or more, the ECM turns the two VSVs On or Off and operates the IAC valve.
3MZ-FE:
The ECM opens and closes the Intake Air Control (IAC) valve No. 2 in response to engine speed (RPM/NE). This system improves intake manifold tuning for better efficiency at low and high engine RPM. When the engine speed is 4,000 RPM or less and the throttle valve opening angle is 30° or more, the ECM turns the VSV On or Off to operate the IAC valve.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.