7M-GE ACIS Reference Thread
- Thread starter Ma70.Ent
- Start date
why does that top part show the system working backwards, low rpms the valve is horizontal and high rpms the valve is vertical sealing the two sides shut.
It's not backwards. It's supposed to be closed at low rpm and open at high rpm. Longer runner length increases lower rpm torque. Shorter runner length increases higher rpm torque.
So would this system not functioning properly cause a 'dead spot' in the power band between 3-4k rpms? The car then pulls fine past 4k to redline. I have the ACIS hooked up to the vacuum, but not to a VSV. I have several VSV's, but do not have a part number for which one is which. Any help on that?
No. It depends on how it would fail, but a likely scenario is the solenoid on the VSV freezing. The default position of the valve is open. The car would be a little sluggish down low, then take off in the upper range.
MPR;1803756 said:
ohhhnow i see it i was confused on how it really works i was looking into the amount of intake volume more than actual intake runner length when its open the whole thing has a shorter path to run with when its closed the intake has a longer runner length for air volume.
When the valve is closed, air pulses from the valvetrain bounce back up the intake. They hit the closed valve and come back down providing a mild supercharging effect. And yes, the valve being closed provides a longer runner. That makes for more volume only at low speed due to the higher velocity. At high speed, the smaller plenum can not fill the runners fast enough, so the valve opens allowing more volume at higher engine speed.