I know we've talked about the variable intake plenum before, where it opens and where it closes, how to modify the EMU so it enables it to work but I dont recall and couldnt find a thread where we talked about the actual mechanical functioning of this feature.


I know something happens at around 4300RPM and that at 6200rpm something else happens but I dont know exactly how?

The reason I am asking is because when I was changing my injectors I noticed that although I had read that the APV was operated by a motor I did find that in the lower intake manifold there was an aluminum "valve" that when turned 90 deg. would open a path for airflow. This valve is operated with a vacuum actuator that is connected to a vacuum solenoid located under the plastic intake manifold. Which valve is this? Is this the one that opens at 4300rpm? If so I'm thinking it wouldnt be opening at all in cars with FI because it uses vacuum to operate and when the solenoid opened under boost it would actually push against it opening. I'm just looking to understand exactly how this variable intake feature works because I am exploring certain posibillities and this would help me out. Pictures are more than welcome if available.

For the people with the Interceptor;
I know this EMS has control over when the APV opens(I'm talking about the one that usually opens at 6200), has anyone opened it all the time? if so, what where the effects at idle? Any input will be appreciated. Thanks.


Chris......Esmeril

 

Ok, I see. That means that under boost the check valve closes and the actuator doesnt receive anything meaning that it stays closed limiting the total airflow reaching the engine. In the N/A engine it will open using manifold vacuum. BTW, this vacuum actuator is the one the opens at around 4300rpms, right?

Also, in theory if using the EMU we decide to lock the APV that opens at 6200rpm on the open position(move it and unplug it) the ECU will throw a CEL but if we leave the resistor that originally came with the EMU harness connected then the ECU will think it is still working properly and wont throw a CEL? Am i right? Thanks.

Chris

 

GTAW,
I also note in the diagram you posted that what I thought to be the secondarry shutter valve is actually the VDI which doesnt do anything but equalize both sides of the intake manifold above 7200, this isnt working on my car since it is not getting any vacuum at 7200. Do you have any pictures of the lower intake manifold and what the APV and SSV look like, thanks.

Chris

 

First, the only stupid question is the one you decide not to ask...

Well, I am sure that the ones that operate with vacuum arent opening simply because there is no vacuum to open them at WOT because the car is under boost. I also know something isnt opening because the car looses power after 6500rpm which is precisely where it should kick in because of the APV. My Turbo doesnt die with rpm because its big enough, so I am gettin all this TQ and I am almost at 300whp at 6400rpm. With this Hp figure at 6400 I should be at least at 330whp at 8000-8500rpm if the APV where to open. It is really limiting me.

I would greatly appreciate the pics of the lower manifold. Thanks.

Chris

 

[QUOTE=
I took out the whole APV assembly to make a custom lower intake, so any pictures would only show the bare bones of the manifold, it you still want them let me know.[/QUOTE]

Hi,
Send me all the pictures you can. I jsut want an idea of location so I can plan out what I am going to do. Thanks.

Chris

 

good thread---I wonder what Pettit is doing? I know these are on the lower manifold but the solenoids etc are part of the upper manifold and Pettit replaces the upper one with their custom make.
olddragger

 

Even if Petit left the "vacuum canister" it is still FI so there would be no vacuum under full throttle so they wouldnt be opening even if the solenoids where working unless they have something else we dont know about...

GTAW, where are the pics of the lower manifold?

thanks.

Chris

 

Not related to the thread question.

GTAW, in your last pic, the SSV, are those black *stuff* carbon deposit ?

if it is then, DAMN, I need to run my car harder.

 

I see, so its like the brake booster, that makes sense. What about long high gear runs, this could cause a problem.


Chris