By Pass Valve Operating Details - 355 / 5.2

In reading the WSM & Owners Manual, the bypass valves opens when the engine RPM'***** these levels in each of these gears:

By-Pass Valve operating range:
1, 2, 4, 5 & 6 = 2800+ RPM
3rd gear = 4000+ RPM

I assumed the valve opened up once the RPM's were reached. Period.

However, I need to have the throttle almost wide open to get the vacuum necessary to open the valve....

To check, I hooked a vacuum gauge up and was able to watch what happened while I drove around. Here is what I found:

1. The vacuum was not engaged unless I was at (or above) the specified RPM/ Gear range...but also had the throttle wide open. Just cruising above the RPM/Gear combination did not generate vacuum to open the valve....is that normal & correct?

2. In 2nd gear the range was 4,000 rpm. Is the manual printed correctly? There have been more than a few mis-prints in that thing.

Thanks in advance for any help and guidance.

 

Thank you Mitch. I appreciate hearing that from someone who knows these cars way better than I ever will.

Any guess on the 2nd gear limits I found during my test?

 

Looking at the two solenoid valves from the rear looking forward....

The left hand one operates the by-pass valve
The right hand one feeds the cut off valve.

Left hand top hose connection goes to a metal tube tack welded to the cross bar.
the outlet of that tube is forward of the by pass valve and to the right.
Connect hose from by pass valve to that tube.
- or -
Connect hose from bypass valve to top hose connection on the LH solenoid valve.

Right hand top hose connection feeds to the cut out valve.

Bottom LH & RH hose connections are teed together and go to the vacuum tank.

Follow the diagram here: http://www.ricambiamerica.com/parts_catalogs.php?M=FE&P=&V=diag&I=1450

 

Pretty heavy handed....but you get the idea. The orange section is the steel pipe tack welded to the steel air pipe. Hope it helps.....best of luck
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I am never really sure of anything anymore.

Line #37 in table 8 is the same line #22 in table 14. http://www.ricambiamerica.com/parts_catalogs.php?M=FE&P=&V=diag&I=1456

It splits into two lines where each has a check valve and attaches to the throttle body. Follow the "=" signs:

.............................======= check Valve =====throttle body
#22 on table 14..../
===============
...........................\====== check Valve =====throttle body

You can see the two check valves in Philippe's first image. The two open ends were connected to the throttle body RH & LH The one running off the page to the right is #22 on table 14 which picks up as #37 on table 8 and goes to the tank.

It looks like he replaced his with a single unit before the tee instead of separate ones afterwards. Might have to get me one of those!

 

Lets be clear about that orange section. That orange piece is a small tube that is welded to the back side of the air pipe that feeds the extra air into the exhaust. They are separate systems.

The line from the throttle body feed the vacuum tank. The other line from the tank provides vacuum at the base of each solenoid. the top of each solenoid has control vacuum that is engaged when the solenoid switch is activated. If the bypass valve solenoid is engaged, the vacuum flows and pulls the bypass valve open. If the solenoid closes, the vacuum is released and the valve closes.

The exact same logic holds true for the other solenoid and the cut out valve.

If your car has the right hand side of the orange line in my diagram plumbed from that nipple to the tank, I think your valve will be open all the time. You have by-passed the solenoid switch and the control that goes with it.

In addition, how are you getting vacuum to the cut out valve on the other solenoid valve? one port on the tank goes to the throttle bodies to provide the vacuum. The other now goes direct to the by pass valve. You are out of ports Must be a wayward tee in there somewhere????