air intake manifold runners

[QnecSHO]

Along with my other problems with the SHO
for some reason my air intake system is acting funny. The valve on top are fluttering constantly.
I dont know how else to describe it those little vacuum valves on top of the engine are fluttering,
opening and closing extremely fast.
It slows down after it warms up.
I dont know what is causing it.
If someone has an idea i would appreciate it.

 

[Huntervf]

Need more info! Post year & engine please!

Also, where are you located in Michigan? If you're not too far from Kalamazoo I'd be happy to take a look at it for you.

 

[philallemang]

i would say this man is trying to say that his secondaries are going crazy. thats what i get from his post, especially from the vacumm part.

 

[SHO_Driver]

Check the two vacuum lines running from each butterfly valve. If they are not leaking check the main vacuum control between the manifold and the firewall. There are ways to test the system.

 

[QnecSHO]

sorry for the lack of info, its a 93 3.2 ATX.
all vacuum lines seem to be ok. I can unplug
the solenoid that control those valves and of course they stop, but I can still here something
triggering elsewhere, just as fast as the butterfly valves were opening and closing,sounds like it is towards the firewall side but around the engine.
I mention this because when that noise stops
the butterfly valves stop fluttering.
So i think those butterfly valves are doing what their supposed to, but where they get their signal
is where i think the problem might be.
Does anybody know what controls those valves?

I live in the downriver area, south of Detroit.

<small>[ September 19, 2002, 06:51 AM: Message edited by: QnecSHO ]</small>

 

[projectSHO89]

First, check this thread. It shows the vacuum circuit for the secondaries: http://www.shoforum.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=17;t=002502#000002

The vacuum valve, named by Ford as the Idle Air Control (not to be confused with the Idle Speed Control Solenoid), is the valve mounted on the rear (firewall side) of the intake manifold. It should have a vacuum supply line going from the vacuum manifold to the valve. The switched vacuum then is routed to each of the secondary butterfly valves (called Idle Air Control Vacuum Motors).

The vacuum is switched under the control of the EEC-IV. The red wire going to the IAC is a constant HOT while ignition is on. The LG/PK (89 EVTM colors) wire is switched to 0 volts in order to energize the valve and apply vacuum to the motors, closing the butterfly valves. At 4K rpm, that 0 volt signal is removed, de-energizing the valve, removing the vaccum from the motors, and allowing the butterflies to open.

Your symtom indicates that you are getting some vacuum to the motors, but not enough to properly close them. Look first for a vacuum leak in the vacuum lines. Then, check the voltage on the signal side of the valve, looking for a ground.

You may need both a vacuum guage and a multimeter to properly test the complete circuit, although there are a few shortcuts.

Steve
89