Vacuum Troubleshooting

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Thatblackraptor

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Started to troubleshoot the IWE today after some road noise on my last road trip. Put 1500 miles on the truck and couldn’t get past the noise.

Replaced the IWE actuator on drivers side a few months ago. IWE on both driver and passenger holds vacuum around 20in applied and doesn’t drop. I then applied vacuum to the system after the solenoid (testing each IWE and tubing) and it held vacuum as well so no leaks.

Reading from engine side of check valve. This seems low? Only 14in of vacuum applied to check valve from intake?
A3BABE09-9CBC-4250-9147-F0704FD9D341.jpeg

Drivers side reading from IWE line. Seems low at 9in of vacuum
BCA8D258-F97A-42B6-B41B-D6D06D36E2F9.jpeg

Passenger side reading from IWE line. Almost 6in higher than the driver side.
6B4DD481-DA7F-45B2-972D-BCA89D8A677B.jpeg
 

Old-Raptor-guy

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What altitude are you at? Vacuum from engine will be less the higher the altitude. I am at 4700 ft and I see 17ish inches of mercury is about normal. Also I would check at the brake booster for reference, both IWE should see the same Vacuum since they are "T-ed" together and not parallel (or ran separately from one another).
 
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Thatblackraptor

Thatblackraptor

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What altitude are you at? Vacuum from engine will be less the higher the altitude. I am at 4700 ft and I 17ish inches of mercury is about normal. Also I would check at the brake booster for reference, both IWE should see the same Vacuum since they are "T-ed" together and not parallel (or ran separately from one another).

That’s interesting! We’re at roughly 6,700ft here in Colorado. What concerns me the most is the difference in sides. The passenger side being almost double what the drivers side is which is where I’m having issues.
 

Old-Raptor-guy

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That’s interesting! We’re at roughly 6,700ft here in Colorado. What concerns me the most is the difference in sides. The passenger side being almost double what the drivers side is which is where I’m having issues.
Absolutely the side to side difference should be investigated.

As far as "interesting" vacuum is negative air pressure. You can't have as high of vacuum as at sea level if your air pressure is lower, which it is at altitude.

It was always fun calling Ford engineering hot line 30 years ago with data and they going WTF on some readings until I told them my altitude. Something like 80% of the population live below 3000 ft.
 
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