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How To:- Check Your ACIS System

This guide will show you how to check to see if you have a fully working ACIS system.

This guide is for testing the ACIS system on the N/A MR2, however it can also be used to test the T-VIS system on the turbo MR2.

The simple test:
To see if the ACIS is working as it should be follow this simple test -

Firstly, with the engine idling, see if the actuator mechanism has moved the internal butterflies to the 'closed' position -


Next, disconnect the actuator vacuum pipe. You should then see the mechanism move to the 'open' position -


Next, reconnect the vacuum pipe, allow the mechanism to move into the 'closed' position once more then switch off the engine. With no power going to the ACIS solenoid the mechanism should now move to the 'open' position.

This test makes sure that the solenoid, actuator and butterfly mechanism are working as they should be and that the solenoid filter is clean and free from blockages.


'That didn't work'

If that test didn't work and something is wrong with ACIS then we need to diagnose the system.

Firstly check the actuator mechanism by trying to move it by hand. The mechanism can get rusty and is prone to sticking so may need to be freed off with the use of some WD40 or equivalent.

If the mechanism moved freely then we need to test the actuator.

Remove the solenoid pipe from the actuator and fit a length of hose to it -


Now apply some vacuum to that pipe. You should see the mechanism move. If it does then the diaphragm in the actuator is fine. If it doesn't then the actuator is at fault and needs replacing.

If those tests went ok then we need to check the vacuum hoses. Take a look at all the ACIS hoses for splits and cracks and make sure they are all securely pushed on to the actuator, inlet manifold outlet, solenoid and vacuum reservoir. If they look fine also check the vacuum reservoir for splits and cracks.

The solenoid and vacuum reservoir are located underneath the inlet manifold -


You can see the solenoid, with the filter attached, underneath the vacuum reservoir shown in the picture.


Testing a solenoid

If all that is good then we need to check the solenoid and its wiring.

Remove the vsv, which is secured by a 12mm bolt, and take off its vacuum hoses and wiring connector.

Inspect the solenoids wiring connectors, both on the loom and on the solenoid itself and make sure the terminals are nice and clean and free from corrosion. Also check to see if the wires going in to the connector are secure and not corroded.

Now to test the solenoid -

Using a multimeter, set to resistance (ohms), test across both the terminals for continuity -


This tests for an open circuit. If there is no continuity then replace the solenoid.

Now check for ground by testing each terminal against the body of the valve -


If there is continuity then replace the solenoid.

Now connect a hose as follows -


Now blow through the hose. You should feel the air pass through the filter side of the solenoid (closest to the wiring terminals).

Next apply 12v across the terminals of the solenoid and repeat the test. This time the air should go through the other side of the vsv, closest to the hose.

If those tests do not work and no air comes out then the solenoid is blocked. If the air only comes out of one port then the solenoid is stuck and may need replacing.


With the solenoid removed from the car also check the filter -


Check to see if air can pass through the filter ok and it's not blocked up.

Finally test for voltage at the loom vsv connector. You should be getting 12v across its terminals with the ignition switched on.

Note: When refitting the solenoid the vacuum hoses are fitted as follows -
From the inlet manifold feed the vacuum hose goes to the vacuum reservoir. From the 90 degree outlet on the reservoir the hose goes to the horizontal outlet on the solenoid (in line with the filter). Then from the vertical outlet on the solenoid the hose goes to the actuator.



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