No heat build up if you just unplug it. The rattle noise you are hearing is the dump gate. No vaccume to hold it closed. With it unpluged there are no signals going back to the pcm to cause a boost dump. Plus the vacumme stays connected and no heat buildup.

SeeYa.

 

Since there seems to be a lot of confusion on this subject, let explain how it works, and that should answer both questions below:

"Wait, so, ultimately, is it bad to disconnect the boost soleniod?????"

"If you leave it unplugged all the time then won't it build up heat the same way as rerouting the vacuum lines??? I need a lil' vacuum relief on the street too! On a real hard 1 to 2 shift she'll dump boost all the way through the gears until it has time to reset."

There are two components that are part of the by-pass system. One is the vacuum operated by-pass itself, the other is an electric solenoid that ties into the vacuum going to the soleniod. The by-pass works just like any aftermarket blower by-pass. It has vacuum hooked to it, and when vacuum is present (no load) the by-pass opens, allowing some air to bypass the blower and not build up pressure (boost). The reason for this is to keep excess heat during normal operation down. That is why Kenne Bell started doing by-passes on thier blowers. You could cook and egg on a non-by-passed Kenne Bell blower at idle. If you disconnect the vacuum line going to the by-pass, you are now keeping it closed ALL the time. When you are at idle, it's closed, build up heat. When you are crusing, it's closed, building extra heat. You only want it to be closed when you're under boost, which it already does.

The solenoid, is an electric valve that is tied into the PCM. There are several failsafes in the PCM strategy. In case of a potentially damaging powertrain situation, the PCM takes action to save the drivetrain until a dealer visit can occur, and one of thoese actions it takes is to open the by-pass and not allow boost to build up, furthering possible damage. Is it bad to disconnect the solenoid? It can be. If you leave it off, and you run into a problem and the PCM wants to kill boost, then you could make things worse. Most leave it disconnected, myself included. The BEST thing to do, is simply disconnect it at the track, and plug it back in before you leave. The reason some loose boost on the track, is a failsafe called "Break Torque" When the PCM see the break pedal on, and the throttle at WOT at the same time, that sets off a failsafe. This is what happens at the track, usually the result of a burnout.

Hope this helps!!

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SAL - TEAM PSP
web- www.powersurgeperformance.net
E-mail sales@powersurgeperformance.net
tech@powersurgeperformance.net
F-150 Online Supporting Vendor

 

I'm still a little fuzzy on one issue... If you unplug the solenoid electrically will there still be a build up of boost at idle and cruise??? If so, then there's no difference than the Vacuum mod other than an eraseable code being set..... or maybe I'm just missing the boat!

 

Undy, the solenoid is OFF unless the PCM commands a boost shut down. So in it's OFF state (no current going to it), the by-pass works like normal.

------------------
SAL - TEAM PSP
web- www.powersurgeperformance.net
E-mail sales@powersurgeperformance.net
tech@powersurgeperformance.net
F-150 Online Supporting Vendor

 

This is a very interesting and helpful post. At least I know now how to deactivate the boost shut-off, until I can sort out my shifting problem.

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I'd rather have a bottle in front of me than a frontal lobotomy.

'84 Alan Record Carbonio, Aerospoke wheels, Campy brakes.

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13.39 @ 102.5

2001 Kevlacat 2400, twin 115 Evinrude FICHT, Raytheon VHF, radar, autopilot and GPS chartplotter/fishfinder.



gmvye@pacbell.net

 

I agree, teeing off is not the right way of doing in. I just leave mine disconnected all the time and not one problem in 2 years and over 40K.

Thanks for clearing that up for everyone Sal. I know many have wondered...