It Doesn't Need an Engine
Senior Member
Joined: Apr 2020
Posts: 538
Likes: 427
I find it hard to believe that a real mechanic or even a qualified tech listened to that noise and said "replace the engine".
I have had a stethoscope in my tool box for 20 years to isolate engine sounds.
Heck before that I used a long screwdriver held to the ear and the suspected area of concern, just like the old timers taught me.
The Mustang and hotrod guys delete the use of the runners with a tune and lock them open.
Then they scrap the solenoids and vacuum actuators completely to clean up the engine bay.
I have had a stethoscope in my tool box for 20 years to isolate engine sounds.
Heck before that I used a long screwdriver held to the ear and the suspected area of concern, just like the old timers taught me.
The Mustang and hotrod guys delete the use of the runners with a tune and lock them open.
Then they scrap the solenoids and vacuum actuators completely to clean up the engine bay.
Senior Member
Joined: Oct 2020
Posts: 1,958
Likes: 659
From: Brandywine Md
Perhaps not. Wouldn't make sense. If you went full throttle you would louse most of the vacuum so the default position would have to be open so at idle, with a high vacuum the diaphragm actuators will close the runner plates, if I'm logically thinking this correctly.
Not knowing for sure what position the runner plates are in when the actuators are at rest (no vacuum), will leave me questioning. Which is it?
In order to understand the functioning of this particular design by Ford I've got to know this first.
5 Year Member
Joined: May 2016
Posts: 98
Likes: 62
From: Windsor, Ont.
I actually had the functionality reversed in my original post, sorry. I edited it to correct things.
The default position has to be in the open (unblocked) mode, this is because there would be a significant power loss from the engine if the system ever failed in the blocked position for any reason, due to the airflow restriction. The diaphragms have internal springs inside which keep everything in the open position, until the solenoids are commanded and allow vacuum to overcome the spring force and cycle the plates.
There is actually a pretty complex end of line testing procedure to verify how fast (in milliseconds) the plates take to cycle in both directions and what the time delta is between the two banks from the time vacuum is applied until they reach full travel. We test every part 100% and log all the data in a traceability system.
Hopefully that helps.
The default position has to be in the open (unblocked) mode, this is because there would be a significant power loss from the engine if the system ever failed in the blocked position for any reason, due to the airflow restriction. The diaphragms have internal springs inside which keep everything in the open position, until the solenoids are commanded and allow vacuum to overcome the spring force and cycle the plates.
There is actually a pretty complex end of line testing procedure to verify how fast (in milliseconds) the plates take to cycle in both directions and what the time delta is between the two banks from the time vacuum is applied until they reach full travel. We test every part 100% and log all the data in a traceability system.
Hopefully that helps.
Senior Member
Joined: Oct 2020
Posts: 1,958
Likes: 659
From: Brandywine Md
I actually had the functionality reversed in my original post, sorry. I edited it to correct things.
The default position has to be in the open (unblocked) mode, this is because there would be a significant power loss from the engine if the system ever failed in the blocked position for any reason, due to the airflow restriction. The diaphragms have internal springs inside which keep everything in the open position, until the solenoids are commanded and allow vacuum to overcome the spring force and cycle the plates.
There is actually a pretty complex end of line testing procedure to verify how fast (in milliseconds) the plates take to cycle in both directions and what the time delta is between the two banks from the time vacuum is applied until they reach full travel. We test every part 100% and log all the data in a traceability system.
Hopefully that helps.
The default position has to be in the open (unblocked) mode, this is because there would be a significant power loss from the engine if the system ever failed in the blocked position for any reason, due to the airflow restriction. The diaphragms have internal springs inside which keep everything in the open position, until the solenoids are commanded and allow vacuum to overcome the spring force and cycle the plates.
There is actually a pretty complex end of line testing procedure to verify how fast (in milliseconds) the plates take to cycle in both directions and what the time delta is between the two banks from the time vacuum is applied until they reach full travel. We test every part 100% and log all the data in a traceability system.
Hopefully that helps.
It helps to clarify the default no vacuum to the diaphragm actuators as OPEN, unrestricted.
Getting back to idle from your original post. Are the runners open or closed when idling?
