Boost Bypass install instructions (with pics).

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Government Slave
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The mod is good on a lightning because the PCM dumps boost on the 1-2 shift for torque reduction, no clue whether the 03 does this or not.


I do this mod to my L at the track, then put it back to stock in case there is a valid reason for it dump.
 

Poison_S

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After doing a little reading of this and other related threads, I have to think that this procedure, overall, would have a negative outcome. We are talking about plugging the only way we have to bleed wanted or unwanted pressure off the forced induction system.

What happens to that unwanted boost "shock wave" when the throttle is off and the boost is still up?

It is going to bounce right back to the supercharger, right?

That cannot be good over the longterm.

Anyone with complete knowledge of this system that can further clarify this condition? :shrug:

I'd hate to see some people getting short-term boost gains at the cost of engine longevity.

I don't mean to cause panic and I may be totally off on this, but I am concerned enough to post anyway.
 

BBriBro

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Originally posted by Poison_S
What happens to that unwanted boost "shock wave" when the throttle is off and the boost is still up?

It is going to bounce right back to the supercharger, right?

Sounds like you are referring to a compressor stall that occurs with turbo charged cars that don't have a blow off valve or diverter valve. I'm not sure if this is a concern with a supercharger, because even if there is a shockwave that travels back to the "rotors" they certainly won't stall or slow down since they are mechanically driven.
 

gchronis

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Yeah, but it will create an unecessary strain on the rotors, won't it? I'm not the expert here, either. I have just always been wondering this myself ever since I first read about the bypass mod. This possiblity is why I haven't done it.
 

larryc7777

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I came in on this thread really late but I have a couple of questions if anybody has answers. What situations cause the boost bypass to activate? I think that 1 of them is when the Traction Control activates & I think that another is when a "lift" shift is performed(as opposed to a powershift) while pushing the car hard. Possibly another situation is if the over-rev shutoff is bumped. Does anybody know if I guessed right on the points? Does anybody know of other boost bypass triggers? I'm trying to decide if this mod is worth the risk if a valid overboost situation arises. Thanks, Larry
 

ygohome

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Originally posted by 03blackvert
Since the solonoid appears to be controlled by the PCM program, why don't the chip makers tweek the operation so with a smaller pully it doesn't dump, but if some the other "bad things" happen to your engine it will?

I believe some tuners have done this. Amazon Racing, for example, programs their chips to handle the boost bypass.
 

Jon

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Originally posted by gchronis
Yeah, but it will create an unecessary strain on the rotors, won't it? I'm not the expert here, either. I have just always been wondering this myself ever since I first read about the bypass mod. This possiblity is why I haven't done it.

Ok, if you guys don't mind I'll be the expert...

There is no shockwave associated with the roots blower design. Instead, we get a huge, but harmless vacuum spike upstream of the rotors.
 

IUP99snake

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Originally posted by Poison_S

What happens to that unwanted boost "shock wave" when the throttle is off and the boost is still up?
It is going to bounce right back to the supercharger, right?
That cannot be good over the longterm.
Anyone with complete knowledge of this system that can further clarify this condition? :shrug:

Here's the skinny on that issue:
Compressor surge will occur with a turbocharger or cintrifugal supercharger, because the boost is being created before the throttle body. So, when you let off the gas, and the throttle body closes, the engine is still spinning, and there is still boost that has nowhere to go. Thats where a blowoff valve comes in. It vents off the boost that is trapped inbetween the turbine and the throttle body when you let off the gas.

You will NOT have this problem with roots-style blowers because the boost is being created after the thottle body, straight into the motor. When you let off the gas, and the throttle body closes, the extra boost just goes through the motor, and a vacum is created within the supercharger.

I read somewhere that the boost dump on lightnings was for when they were beat hard on hot days, to avoid pinging or spark knock. My friend would tell me that his truck would feel like it was down on power sometimes, especially on a hot day, or after a pass. When he fixed it, voila! the down power was gone!
 

Rick@Amazon

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Originally posted by 03blackvert
Here's an interesting question. After reading some of the L stuff it appears boost dump may happen from a number of conditions, not all of which we want to prevent. Since the solonoid appears to be controlled by the PCM program, why don't the chip makers tweek the operation so with a smaller pully it doesn't dump, but if some the other "bad things" happen to your engine it will?

With my 03 cobra programs I take care of this in the chip. I've been doing this since August. ;-) I feel it's safer to do it this way because I don't modify the safegaurds of the system.

Rick
 

SoCalBlk03

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Thanks for the detailed instructions. I finally gathered the courage to cut my lines. I did a little fine tuning to it though. I used an acquarium T and rubber vaccum line. I wanted to keep the dump valve line intact. I spliced farther down the line so I could hide it better as well. Here's a pic.
 
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SoCalBlk03

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Originally posted by IUP99snake
soooo.... has this actually helped anybody with power?

-Homer

Good question, the car feels quicker. The boost gauge seems to be more active as well, boost is coming up sooner at lower rpms. No dyno data on it though.
 

Coyote 5.0

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Thanks for the info
I had no idea about this mod. When Steeda did my CAI the mechanic told me he did a boost by pass mod. Now I Know!!!
 

SoCalBlk03

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Originally posted by 03DarkShadow
i know someone has already asked this question. Will unplugging the solenoid do the same thing??

You'll set a soft code and an SES light until you reconnect it. Additionally there's always the chance it'll affect PCM scheduling while the error is sensed. By Bypassing the vaccum line the computer is fooled into thinking the stustem is operating properly.
 

Coyote 5.0

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The mod is easily done and undone if necessary. I just removed mine and I don't feel any difference with normal or hard driving.
I could understand if your at the track not wanting the dump. I ask myself how much would Ford save not putting the dump system on if it wasn't needed???
 

BOOOOST

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Originally posted by SoCalBlk03
You'll set a soft code and an SES light until you reconnect it. Additionally there's always the chance it'll affect PCM scheduling while the error is sensed. By Bypassing the vaccum line the computer is fooled into thinking the stustem is operating properly.

Just had to bring this back up to the top, because this statement is incorrect (nothing against you SoCalBlk03). It sets a "soft code" that will not trigger an SES light. This particular codes does not affect any of the strategies; it's totally harmless. One can easily clear the code by leaving the negative battery cable off for approx. 5 to 10 min., or buy plugging the connection back up and doing a few key on/of drive cycles (no, just turning your key on/off several times does not make it go away, so that is not what I was inferring, lol).

The easiest way of fixing the boost dump is by just unplugging the electrical connection as previously discussed. It's safe everyone, do not worry.
 

Lethalchem

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Originally posted by BNASPLT
The easiest way of fixing the boost dump is by just unplugging the electrical connection as previously discussed. It's safe everyone, do not worry.

If it's safe to disregard this mechanism, negating it's function, then what's it's purpose for being on the car? Is it not a precaution to a valid concern? Surely it's not a useless piece of equipment?

I'm not arguing with you, I'm just trying to understand the pro's and con's of the mod:)
 
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