IMT (Intake Manifold Tuning) System Description

IMT (Intake Manifold Tuning) System Description
The IMT (Intake manifold tuning) system consists of the following items.
^ IMT valve (1) included in the intake manifold (2)
^ IMT valve actuator (3) fixed on the intake manifold
^ IMT vacuum solenoid valve (4)
^ Vacuum tank (5)
The vacuum tank contains the one way check valve (6) to maintain negative pressure constantly regardless of variation in the intake manifold pressure.
There fore, the vacuum tank, supplies the IMT vacuum solenoid valve actuator with stable negative pressure in the whole of engine speed ranges.





The IMT system varies effective length of the intake pipe by opening and closing the IMT valve (1) in order to improve air volumetric efficiency.
As the intake valve in the cylinder head is opened and closed repeatedly, intake air pulsation always exists. If the intake valve is opened when the air pressure is momentarily maximum in the intake manifold, the intake air volumetric efficiency is increased. This momentary maximum air pressure depends on the effective intake pipe length.
When the IMT valve is totally closed [A]:
The effective intake pipe length is longer. The engine torque in the low engine speed range and the high engine speed range drops, however it is improved in the middle engine speed range. When the IMT valve is fully open [B]:
The effective intake pipe length is shorter. The engine torque in the low engine speed range and the high engine speed range are improved, however it drops in the middle engine speed range. The IMT system utilizes above-mentioned characteristic of the engine torque. The IMT valve is closed in the middle engine speed range, and opened in the low engine speed range and the high engine speed range.
In this way, the engine torque is improved in the whole of engine speed range.











Cross-reference table between valve operation and intake pipe length