The intake manifold inspection is quite complicated. First, check its tightness. For this, start the engine and close the air flow meter inlet with your hand. If there are no faults in the intake line, the engine will stop. If there are cracks or burnouts in the manifold, the engine will continue working, and a hiss will come from damaged areas.
Examination can also be carried out on a shutdown engine. For this, close the connecting pipe inlet opening, apply a soap solution to the suspected faulty areas and blow the intake line with compressed air. The solution foaming indicates that the system is unsealed. At a service station the intake manifold is checked for leakage with the help of a smoke machine.
Also check the operable condition of the intake manifold runner control valve. For this, connect the multimeter to its terminals and measure the resistance. If there is no resistance, the integrity of the solenoid valve winding is impaired. Then you have to start the engine, raise the speed to 3500-4000 rpm and see if the runner valve situated on the left side of the intake manifold is working.
You can check by hand whether the swirl flaps are stuck: their actuator rods are located outside the housing. You can check whether they activate at the right time with the help of a vacuum pump. For this, connect it to the corresponding pipes and see at what underpressure the rod starts moving, and then compare the received data with those stated in the technical documents.
