How To: Eliminate Boost Drop Off (eliminate boost solenoid)

styre

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I just came across this thread and want to do it, but a little nervous about the extra boost thats going to be produced in the higher rpms. Do you guys think it will be enough to make the car run lean up top? I dont really want to get on the dyno to check since my tuner is over an hour away. Ive got a hand held predator tuner so I could always add a little fuel if needed.

I would like to know if it leans out up top also?
 

20SVT03

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It will definitely lean out up top. I was wot going down the 1/4 mile watching the a/f gauge reading 16.7!!!!! I am really surprised there hasn't been anyone elsewhere notice something was up or had a major problem that has said how great this mod is. I bought a new vacuum harness and ran again now I'm back to 11.6 average a/f all the way down the track
 

hookandpull

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It will definitely lean out up top. I was wot going down the 1/4 mile watching the a/f gauge reading 16.7!!!!! I am really surprised there hasn't been anyone elsewhere notice something was up or had a major problem that has said how great this mod is. I bought a new vacuum harness and ran again now I'm back to 11.6 average a/f all the way down the track

So are you saying your back to stock?
 

brian97cobra

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It will definitely lean out up top. I was wot going down the 1/4 mile watching the a/f gauge reading 16.7!!!!! I am really surprised there hasn't been anyone elsewhere notice something was up or had a major problem that has said how great this mod is. I bought a new vacuum harness and ran again now I'm back to 11.6 average a/f all the way down the track

I do not tend to believe this affects every car as mine did not do this with the eaton or my Whipple. Both were tuned.

would a tune cure the lean condition and make this a really good mod?

I believe that with a good tune it will not be a problem.
 

20SVT03

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I did not go back to stock as in complete factory I just bought the original vacuum harness as if I never performed this mod. Brian97 maybe right but I would make sure that you know exactly what the outcome effects are with a A/F gauge and some track or dyno time
 

hookandpull

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I did not go back to stock as in complete factory I just bought the original vacuum harness as if I never performed this mod. Brian97 maybe right but I would make sure that you know exactly what the outcome effects are with a A/F gauge and some track or dyno time

So what your saying is... That you went back to stock as far as your vacuum assembly goes :shrug: I have a Bama tune and 2.76 pulley and my car has the so called "steeda" kit on it. I have been dealing with issue after issue after issue with this damn car (has 124,000 miles). The person obviously didnt take care of it. Anyways I have had this rig for 4 months and have been replacing shit it seems like every week. I finally finish the fuel system and the car ran great for 2 days. Now all of the sudden it feels like a dog at 25%-50% throttle when just driving around. The best way to describe it is that it feels like the car is pulling timing. I have already fixed the inntercooler pump. So my guess is that maybe it is an issue with my boost bypass or even a bypass actuator problem.... my longft1 and longft2 were both a solid 1. and a .98 / .96 at idle
 

01trublue cobra

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I have this mod with no problems at all and a perfect A/F ratio, but then again I plugged that lower nipple on the dump valve, since the stock configuration basically it runs into a sealed canister nipple thingy and no where else, so it was meant to be sealed.
 
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Oakley

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I have this mod with no problems at all and a perfect A/F ratio, but then again I plugged that lower nipple on the dump valve, since the stock configuration basically it runs into a sealed canister nipple thingy and no where else, so it was meant to be sealed.

It was sealed but it also had the canister and 2 feet of hose so the pressure dont build up. If you manualy open the valve, then plug the lower port with your finger, the valve will slowly return, but not all the way because of the vac.
 

Oakley

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What do you do with the vacuum line on the back of the boost dump valve?

I just left mine open. It doesent hurt anything unless the diaphragm is bad then you will loose boost and vac. I guess you could put the canister back on if you dont like it open.
 

metaman

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Don't do this mod its not worth it! You will create a lean condition which is never good. When your ready to race just swap the two lines then swap back afterwards.

Your blower will run hot if you do the old switch the lines deal. You will start generating heat idling in the staging lane and before and after burn out. Then when you actually run, you will hit higher air intake temps sooner and pull timing. You must not have done the mod correctly. My car runs perfect with it.

If you take the time to understand how the boost actuator and vacuum system works, you will discover that this mod does not change anything about how much fuel the car is getting, unless you rig it up wrong and starve your FRPS for boost. If you air fuel is that high with this mod then you must not be getting a boost reference at the FRPS sensor. You are supposed to have one line that goes to the actuator and the FRPS sensor coming off of the bottom port on the back of the blower. Should be cake to set up right.

If you feel vacuum on the bottom port on the actuator when you blip the throttle that makes sense. It makes sense because inside the actuator there is a rubber diaphragm that moves up and down with the actuator rod. As it moves up it will pull a little air through the bottom port like a plunger in a toilet.

It is standard practice to hook up twin screw blowers using this type of vacuum set up without all of the factory crap in place. Many tuners that are very reputable set up cars with the lines reconfigured like this. That is where the idea came from, experienced tuners. All I did was take their info and pictures to it.
 

metaman

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I have this mod with no problems at all and a perfect A/F ratio, but then again I plugged that lower nipple on the dump valve, since the stock configuration basically it runs into a sealed canister nipple thingy and no where else, so it was meant to be sealed.

That is probably ok, however you can prove to yourself that it will not leak vacuum. Go out to the car and pull the vacuum cap off. Now pull the actuator rod down and before you let go of it, put your finger over the open nipple. You will feel the plunger suck your finger skin onto the nipple.

You may actually restrict the travel of the actuator rod if you cap the bottom port due to the diaphragm creating vacuum on the bottom side of it working against the spring and vacuum on the other side.
 

coketo

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I did this mod at the same time i got a tune and i got no problems at all, as far as i know :)

metamam do you think i can have your phone number i have a few questions i would like to ask you about this mod. ill appreciated
 

20SVT03

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I read your original post over and over again and trusted what i saw. I followed every step exactly how you described, except for the wire ties on the vacuum fittings. I am positive I did not perform your mod wrong. Believe me, I really like how clean this made the driver side of the blower look. I just know that after performing this mod I had problems and I confirmed my suspicions with a A/F gauge that the port at the back of the boost bypass valve should not be opened to atmosphere. I understand that a tuner can shut this valve off but i do not understand how they can fix a vacuum leak. My only thought would be to over compensate with more fuel, which sounds like overkill. I am happy with reverting the vacuum harness back to its stock form, so I will just leave it at that.
 

itzl0l

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The only way it is a true vacuum leak is if there is a leak in the diaphram in the actuator. In order for the actuator to function correctly the top and bottom should be seperated by the diaphram....sounds like yours may be ruptured. It works similar to a blow off valve or wastegate actuator...
 

itzl0l

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....fwiw ...per the instructions (optional) I left the lower port on the actuator connected to the factory location in the inlet tube
 

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