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Discussion Starter · #1 ·
Ok I had maxed out my 9psi wastegate springs so I put the 14.7 pound springs in.

This is back when I wanted to see what the car would make with more boost.

I also use the AEM boost controller and here is my problem/question.

If I have the boost controller OFF when I lay into the throttle it will show 21-22psi.

Now those of you that do not know about the AEM it has a "recall" button on it so I can see my max psi that it hit. I just don't understand that if its a 14.7 pound spring how it can spike so high?

Now when I lay into the throttle in like 3rd-4th gear and hold it so I can actually look at what psi its holding its around 16psi.
 

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Not sure if it really pertains to your question or not, but my boost controller went bad once. It held the wastegate closed all the time. We'd get to 25# and let off the throttle. Otherwise there's no telling how much boost it would have made. It's possible that when you turn it off it's just holding the gates closed...???
 

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My halman will spike alittle higher than requested, but nothing like 6 psi more. I know that just adding a boost controller, it adds 1-2psi even on the lowest setting. IE, when I hooked up my Halman, I had 8psi springs in there, but just hooking up the MBC I saw bout 9.5-10ish. So part of the problem could be your springs are 1 bar (14.7) and the boost controller is upping that a bit just cause it is on there...16-17ish...and the spike of 21-22 is just the spike you see when your turbo(s) spool up so quick. If I have my MBC on 16-17 psi...I will spike 19ish then it will quickly drop to 16-17 and hold there till I get out of it. To my knowledge, it is the nature of the beast. By the time the manifold sees the 17psi, the wastegates haven't opened, yet...so the turbos are still spinning up...then as soon as they open...the wheels are still at that speed and you have to give them a sec to spool down...just figured that was the way it was...
 

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Just my .02:

Wastegate springs don't really do anything when using a boost controller. They will still open at their designated spring pressure, but that's when the boost controller will take over by keeping them closed until the desired pressure/spool characteristics are reached. If you run a 9 psi WG spring w/o a BC, then you shouldn't see more than 9 psi. In your case, you could have your BC hooked up wrong, or you could have the setting on your BC set too high. Try running with out the BC to make sure it's not a mechanical issue with the WG. When all is well, you know it was the settings on your BC.

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it could also be a vacum leak causing your boost to spike. like everyone else said i would re-check everything and make sure the lines are all on tight. then go from there.
 

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Discussion Starter · #6 ·
Just my .02:

Wastegate springs don't really do anything when using a boost controller. They will still open at their designated spring pressure, but that's when the boost controller will take over by keeping them closed until the desired pressure/spool characteristics are reached. If you run a 9 psi WG spring w/o a BC, then you shouldn't see more than 9 psi. In your case, you could have your BC hooked up wrong, or you could have the setting on your BC set too high. Try running with out the BC to make sure it's not a mechanical issue with the WG. When all is well, you know it was the settings on your BC.

Yay for my 1,000th post!
Thats the thing, it is doing this with the boost controller turned off.
 

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Discussion Starter · #7 ·
Not sure if it really pertains to your question or not, but my boost controller went bad once. It held the wastegate closed all the time. We'd get to 25# and let off the throttle. Otherwise there's no telling how much boost it would have made. It's possible that when you turn it off it's just holding the gates closed...???
It it was holding the gates closed it would see alot more than 21psi. I know that.
 

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Unhook the boost controller from the wastegates.

Repeat scenerio to check that the problem is either BC related or not.

If it is then you may have a BC problem.

If not then you may have reinstalled something incorrectly when you changed the springs. Or at the new boost level your wastegates can't keep up with how much boost you are pushing.

I'm leaning toward a BC problem or install mistake on the springs though.
 

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Unhook the boost controller from the wastegates.

Repeat scenerio to check that the problem is either BC related or not.

If it is then you may have a BC problem.

If not then you may have reinstalled something incorrectly when you changed the springs. Or at the new boost level your wastegates can't keep up with how much boost you are pushing.

I'm leaning toward a BC problem or install mistake on the springs though.
I agree with this.

If your car controlled boost correctly at a lower level maintaining a higher level should be no problem. Make sure the lines are tight, no leaks, and disconnect the controller and see that it does that way. The gate will still need a reference to operate.
 

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Thats the thing, it is doing this with the boost controller turned off.
That's dangerous man. You shouldn't run with the BC off while hooked up. Then your WG's cannot work properly. If they cant vent pressure then it will cause a spike like that. Plus the installation is totally different with and without a BC. With no BC, your boost reference line should go to the bottom port on the wastegate (assuming you have Tial WG's), that way the boost can open the WG spring at the desired pressure. If your boost reference line is on top of the wastegate then the pressure will keep the spring (back of WG valve) closed and boost will continue to climb. With both ports closed (by vacuum lines) and the BC turned off both sides are seeing pressure (from manifold on one side and from turbo's on the other) and the spring is caught in the middle. To me it seems like what is happening is that eventually the pressure from both sides is compressing the spring enough to let the WG open. Think of it this way...take the WG spring out and place it between the palm of your hands and press together. With enough pressure you can compress it. Now imagine your palms are boost...same theory. In this case it's taking 21 psi from both sides to compress it enough to crack open. It would also help to know how your BC is hooked up.

EDIT: After re-reading...I really need to know how the BC is hooked up. If it is hooked up right and you run with it off, you might damage the solenoid in the BC. UNLESS the AEM literature says that it's safe to be run while being turned off. In which case Shannon is correct that some BC's register a psi or two more than the springs you have installed. We just need more info.
 

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Discussion Starter · #11 ·
I agree with this.

If your car controlled boost correctly at a lower level maintaining a higher level should be no problem. Make sure the lines are tight, no leaks, and disconnect the controller and see that it does that way. The gate will still need a reference to operate.
I remember when the car had a 9psi spring in it when I was on my 18psi tune. When it made 18psi the most the boost controller would show it made (spiked) was 20psi.
 

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Discussion Starter · #12 ·
That's dangerous man. You shouldn't run with the BC off while hooked up. Then your WG's cannot work properly. If they cant vent pressure then it will cause a spike like that. Plus the installation is totally different with and without a BC. With no BC, your boost reference line should go to the bottom port on the wastegate (assuming you have Tial WG's), that way the boost can open the WG spring at the desired pressure. If your boost reference line is on top of the wastegate then the pressure will keep the spring (back of WG valve) closed and boost will continue to climb. With both ports closed (by vacuum lines) and the BC turned off both sides are seeing pressure (from manifold on one side and from turbo's on the other) and the spring is caught in the middle. To me it seems like what is happening is that eventually the pressure from both sides is compressing the spring enough to let the WG open. Think of it this way...take the WG spring out and place it between the palm of your hands and press together. With enough pressure you can compress it. Now imagine your palms are boost...same theory. In this case it's taking 21 psi from both sides to compress it enough to crack open. It would also help to know how your BC is hooked up.

EDIT: After re-reading...I really need to know how the BC is hooked up. If it is hooked up right and you run with it off, you might damage the solenoid in the BC. UNLESS the AEM literature says that it's safe to be run while being turned off. In which case Shannon is correct that some BC's register a psi or two more than the springs you have installed. We just need more info.
The AEM boost controller works with a percentage of the wastegate. So, I cant just set my controller at a certain boost level like "18psi"

For example when I was running 24psi it was set at like 45% (with it spiking 2-3psi above which is normal from what I hear). So since I obviously do not want to run 24psi on pump when I got the car back I figured I would run it with the waste gates off since I really didn't have a reference to what would correlate to 18psi.

From what I know its ok to run with the boost controller off. Pretty much that lets the wastegates do their job. I guess you're saying that isnt good if its still hooked up? I dont understand how turning my BC off would not allow the wastegates to open up b/c if I turn the controller off it will not affect the controller?? Lord im confused.

The reason why Im running with the boost controller "off" is that the lowest % I can set the controller at is 10% and I obviousely do not want to set it at that if it is already spiking so bad.

From what I can see when Im driving the car and in boost that after the boost spike it is holding the correct boost 16ish psi. So still its not like it is holding 21psi all the way thru the gears on my 1 bar springs.

I have the stock tial wastegates (what came with the kit) on. Maybe they just cant get the air out?

Also guys, I did no work to the car I have no time or patcience to do it so I really do not know how to tell you the BC is hooked up, sorry.

Smokin04 can you explain the BC line on the top/bottome for me again? try to make it simple?
 

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The AEM boost controller works with a percentage of the wastegate. So, I cant just set my controller at a certain boost level like "18psi"
^
This is the way my Profec B works as well.

Smokin04 can you explain the BC line on the top/bottome for me again? try to make it simple?
Look here--> http://www.tialsport.com/techincal.htm

Tial External wastegates have two ports. A top port and a side/bottom port. If you were running no BC, your bottom port would be where your boost signal line goes. That way when the boost reaches it's target level (spring pressure) it forces the valve in the WG to open and let the excess boost pressure escape; thus holding boost at desired psi.

When running a BC, (in the simplest terms) both top and bottom ports are connected to a solenoid that is controlled by the brain unit. Boost builds and is measured by the brain unit...it then (based on your settings in the brain unit) tells the solenoid to allow necessary pressure through it to reach the desired settings (boost, ramp rate, safety levels, etc.).

Only other way I can describe it...you have your two ports. Both sides see boost pressure. The BC acts as an adjustable valve that fluctuates pressure like a piston to the top and bottom ports.

So when you run with out your BC on...you take away the actuation of the solenoid, but it still sees pressure. So the pressure is still there forcing its way through the orifices, possibly damaging it.
 

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Im confused
Imagine a river of water. When water is flowing, you can manipulate its flow with an object like a large rock, log, or stop it with a dam.

Think of the water as boost/exhaust pressure. Think of the dam as the WG valve. Think of the BC as the rocks and logs to manipulate it all.

When the water gets flowing fast enough the dam will fail; (also known as the WG opening). So the BC will divert water (boost pressure) to the back side of the dam (WG spring/valve) to reinforce it (keeping the WG closed) until the desired flow is reached.

Clear as mud?
 

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Discussion Starter · #16 ·
Imagine a river of water. When water is flowing, you can manipulate its flow with an object like a large rock, log, or stop it with a dam.

Think of the water as boost/exhaust pressure. Think of the dam as the WG valve. Think of the BC as the rocks and logs to manipulate it all.

When the water gets flowing fast enough the dam will fail; (also known as the WG opening). So the BC will divert water (boost pressure) to the back side of the dam (WG spring/valve) to reinforce it (keeping the WG closed) until the desired flow is reached.

Clear as mud?
I understand that. My point is. When I turn OFF my BC it should not be putting boost to the back of the WG spring to keep it closed. When the BC is off it should allow the WG spring to act naturally and just open when it see's the desired psi 14.7 psi (for the 14.7psi spring) Thats my question.

Another note. On the dyno when the BC is "off" it will show and hold 16ish psi. So its is making more boost on the street (more load) Im beginning to think that when I have the 14.7 pound spring in there that the WG just cant keep up and vent the boost out fast enough.
 

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Another note. On the dyno when the BC is "off" it will show and hold 16ish psi. So its is making more boost on the street (more load) Im beginning to think that when I have the 14.7 pound spring in there that the WG just cant keep up and vent the boost out fast enough.
That's probably right. With the BC off, the WG is free to act on just the spring pressure, BUT keep in mind your top port still has a line connected to it which is where the excess pressure would normally bleed off. With a little excess pressure trapped in that top line, it most likely making your 14.7 pound spring act like a 16-18 pound spring. In fact that vacuum line will probably rupture or leak over time...or worse, you could damage the BC solenoid. Just my opinion.
 
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