Not building boost

[jml1521]

So I went to a rental on Friday and the car was fine building 17pounds of boost and ran pretty strong considering it was warm and humid. Fast forward to that Sunday morning after rental I pulled car out to clean it and take it for a ride and now it's only building 8pounds of boost that's it! Tried different tunes and it did the same thing so it's not that. I checked all my vaccum lines and that looked ok. Any ideas?? Have a Vmp gen 2 on a 07 gt500

 

[Snoopy49]

It sounds like the bypass actuator is not working properly or the bypass valve is sticking and not allowing it to close al the way shut.

 

[stkjock]

/\ good thing to check

also, how old is the blower belt?

 

[Catmonkey]

Might pop the throttle body off and see if the by pass valve is in the closed position. If it's not, there may be something restricting it, or the valve vacuum motor needs to be adjusted so that it closes under tension when there is zeo vacuum.

 

[jml1521]

/\ good thing to check

also, how old is the blower belt?

Gates blue 1 year stock lower and stock 2.67 upper with a metro tensionser I don't think it's belt slip

 

[jml1521]

Might pop the throttle body off and see if the by pass valve is in the closed position. If it's not, there may be something restricting it, or the valve vacuum motor needs to be adjusted so that it closes under tension when there is zeo vacuum.

Took the throttle body off and the valve was spring loaded in the closed position

 

[brian98svtsnake]

Text Jimmy L, he'll figure it out

 

[jml1521]

Text Jimmy L, he'll figure it out

I did going there tomorrow

 

[Snoopy49]

View attachment Supercharger Bypass Vacuum Actuator.pdf

 

[jml1521]

View attachment 52706

Can't see what you posted.

 

[Snoopy49]

You will need to install Adobe Reader.

If you have access to a MityVac, you should checkout the actuator. Just apply vacuum to the actuator port and make sure the actuator rod operates smoothly and does not bind.

 

[jml1521]

You will need to install Adobe Reader.

If you have access to a MityVac, you should checkout the actuator. Just apply vacuum to the actuator port and make sure the actuator rod operates smoothly and does not bind.

Okay thanks

 

[jml1521]

Okay thanks

Which port doesn't it have two of them one on the top and one on the bottom?

 

[Snoopy49]

This is from the 2014 Mustang Service Manual.

Supercharger Bypass (SCB) System
The SCB system allows the high pressure air at the outlet of the supercharger to vent back into the inlet of the supercharger, equalizing the pressure. This eliminates the boost (increased pressure that the supercharger produces) for times when supercharger function is undesirable. The system uses a vacuum bypass actuator, which controls the bypass valve inside the supercharger. The system normally operates with engine vacuum applied to the upper port of the vacuum bypass actuator, while the lower port references the air pressure in the clean air tube to cancel out any pressure difference in the intake air system. The actuator is set to open (bypassing the supercharger) during high vacuum engine conditions. As the throttle is opened and engine vacuum decreases, the actuator closes to allow the supercharger to pressurize the air in the manifold

 

[Catmonkey]

How are determining boost? An aftermarket analog guage or the factory dash gauge? If it's the latter, it's not accurate. It's an inferred reading, although I don't know why it would change.

 

[jml1521]

Aftermarket gauge

 

[1320 Junkie]

How does the car "Feel" Jim ? Losing 9 lbs of boost will register in the Ole butt dyno

 

[jml1521]

Def slower won't spin the tires in 3rd gear on the highway . Jimmy is looking at it tomorrow. It's just really weird I think it might be the bypass but I hope it is something stupid.

 

[1320 Junkie]

Def slower won't spin the tires in 3rd gear on the highway . Jimmy is looking at it tomorrow. It's just really weird I think it might be the bypass but I hope it is something stupid.

Sounds like the body of the bypass seperate or you ripped the bladder inside creating a boost leak
..Ive seen both happen...also I've seen the bypass actually seperate from the metal mounting bracket.

 

[jml1521]

Well My friend Jimmy L found the problem in less than a minute. I don't know how I could of missed it. The vacuum line going to the egr side had melted on the egr tube! A five minute fix.