Why can't I hold boost??
- Thread starter gboromsp
- Start date
- :
- Hemi Ram, 71 Plymth Scamp, 71 Plymth Duster 340, 69 Dart 340/4sp
I dunno....I love my Joep....
StreakinOraNgeX
Member
- :
- Mazdaspeed Protege 03
Virtually all boost controllers especially manual ones will have a spike....also, falling off at high rpms is due to the efficiency of turbo, not boost controller. Ne wayz somebody please check out my thread because no one has answered it yet, it pertains to holding boost and boost controller.jeffmsp said:
kingpin7666
Rough for no reason
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- 03 mazdaspeed protege
buy a metal screw from home depot that fits in the joe p hole for the boost control knob. trust me there will be minimal spike (necessity is the mother of invention)
I'd hate to be the bearer of bad news for ya, but its not the boost controller that is the problem. I have an electronic boost controller (Blitz Dual SBC Single Solenoid), and the boost still falls off to about what you are seeing as well. I hit around 10 psi, then by the time I get near redline, it has fallen down to the 7 psi area.
I got a new corksport exhaust (starts where the apex downpipe starts and goes all the way back), and that helped with bringing boost on a bit earlier, but it still drops off. Granted, it used to drop off to 6 psi and now it drops only to 7 psi, but that is still a drop-off.
So, basically, its a common problem because of the size of our turbo, I believe.
I got a new corksport exhaust (starts where the apex downpipe starts and goes all the way back), and that helped with bringing boost on a bit earlier, but it still drops off. Granted, it used to drop off to 6 psi and now it drops only to 7 psi, but that is still a drop-off.
So, basically, its a common problem because of the size of our turbo, I believe.
i thought EBCs constantly adjust so that boost cannot drop off, trust me its not happening because the turbo cant keep up, I am sure it would love to be spooling 19psi at redline lol I am going to try ditching my cat to help hold the boost, what else can I do lol
Well this is the first mention I have heard of it from anyone... There is one other MBC I'm replacing for someone else that did this. We stand behind the product simply put. It may be something on the install as there are about 12 of them out right now and only 2 of these have done this and the rest are rock solid. I will certainly work with you to remedy the problem as that is very important to us. If you had contacted us we would have worked with you immediately to get this resolved. I suspect it to be a bad MBC... I have one in stock I can ship out to you at no charge in return for the other one. You just have to let me know. The other thing you can do is sometimes if they get to hot they can seize up... if you turn the knob all the way counterclockwise until it locks then back in all the way and then readjust you should be ok.. if that doesn't work we'll replace it for you!
Thanks,
Steve
sales@nsnmotorsports.com
Thanks,
Steve
sales@nsnmotorsports.com
Well mine holds fairly well. The boost goes up to 13PSI and drops to around 10PSI but the funny thing is when I hooked the MBC up backwards it would hold insane boost all the way to redline.Riles said:
I was curious as to what it would do if I installed it backwards so anyway it ran GREAT! It was like a teeny, tiny, sledgehammer. Half throttle pulls up to 5000RPM were pegging 13-15PSI like the needle was glued there.
When I did tip toe up towards the redline it would hold to whatever PSI I was dumb enough to try. (silly)
I of course stopped and switched the MBC back around but the experience certainly had me conjuring up images of forged internals, fuel management, engine mounts, and exhausts.
So if it is in fact the size of the turbo why does it hold so well with an ass backwards MBC?
I emailed Joe about it but he was like, "Drop dead you worthless HIPPIE!"
Or was that Cartman I called? Hmm...
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Well I'm very interested in this either way. I have two controllers out there with complaints of this issue and anotehr 10+ that are not having the issue and almost every one of them holding around 8-10 psi.
You can hook it up backwards... but it then becomes a relieving style MBC instead of a pressure differential style MBC.
Any info anyone has.. (like what Riles posted) is very interesting to me... we want to figure the problem out and solve any issues we can for any and all customers...
No Cartman antics from us
You can hook it up backwards... but it then becomes a relieving style MBC instead of a pressure differential style MBC.
Any info anyone has.. (like what Riles posted) is very interesting to me... we want to figure the problem out and solve any issues we can for any and all customers...
No Cartman antics from us
I am boosting 20PSI with no boost creep and no boost falling. I think the stock wastegate is creating the problem by inadiquit vaccum. You could try to tap you brake booster for vaccum. I moved the wastegate, blowoff valve, and the boost controller vaccum to the booster and it solved alot of problems. This is the strongest point of vaccum. Hope this helps.
That was my guess as well (after pondering it for a while now)... that the stock wastegate might be getting overridden and doesn't have a strong enough signal to hold it's boost. I'll recommend that for anyone having problems and we'll see if that helps them out!
Thanks!
Steve
sales@nsnmotorsports.com
Thanks!
Steve
sales@nsnmotorsports.com
I would like to say that I am in no way upset about Turfburn's product. I really don't know what is causing this problem. Maybe it is the vacuum source. Which is the brake booster line. Anyone have a pic, i'll try it. I just wanna hold 9 to 10 psi without falling off to 5 or 6 psi.
TurfBurn said:
That's cool! I just want to make sure I'm there for customers so I was surprised when I found out you were having problems. This particular problem is of a very high interest to me because it is the second one. I want to figure out where it comes from and then solve it.gboromsp said:
The brake booster vacuum line is the rather large line coming off of the big round black drum looking structure on the firewall that your master cylinder/clutch/brake fluid resevoir is mounted to. You migh need an adapter though to use that as I believe the line is like a 5/16" line and the lines for the turbo and the MBC are typically 5/32"-1/4"
This may have something to do with your wastegate which is where the problem gets to be more complex. GlowMunkey however has one of my MBC's and has the same problem as you. He can put a JoeP on though and it solves the issue. Which makes me wonder if the pressure losses through my MBC are high enough that it is lowering the "signal strength" in the line enough to cause your issue. However, all the other ones are very stable and work very well. Additionally, if the MBC was restricting the signal too much it would actually in fact raise the boost rather than cause it to fall off, as would a vacuum leak. So that is why it seems to be more mechanical in nature. I can get you another MBC out if you wish to see if that solves the problem. Otherwise if you are willing to work on this until it gets figured out that would be wonderful and I'll see what I can do for your time and troubles!
I'd be very curious to see what happens when you T it off the brake booster. That is one of the strongest signals on the car for sure.
EDIT: Attached image with the brake booster and approximate location of the hose identified.
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