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View Full Version : Those with Hallman Pro MBC's or any MBC...



TJHUB
09-28-2005, 06:40 PM
I finally got my Hallman Pro RX MBC the other day. I installed the thing and was able to dial in my boost with in 3-4 tries.

The reason I wanted to try this thing was because I had some surging issues with the car that was both getting worse and more annoying. I was also curious as to how one felt after learning how turbos are controlled.

The result? Absolutely no surging whatsoever no matter what I do. The car definately feels quicker with boost coming on earlier and harder. The only strange thing is now I can hear what sounds like air whistling through a tube. It sounds like it's coming from behind the dash. It's a strange sound because my boost levels are very controllable and stable, as well as where they were before the MBC. I have tried everything from 10 psi to 20 psi. I have it set at around 16 psi for now. What do you think is causing the sound? It's a lot louder than the turbo now. There is a small hole on the output nipple of the MBC. I'm starting to wonder if that's not the noise??

The car also drives okay. Not great, but okay. It's hard enough to drive an auto with turbo much less one with high boost levels. I think I like it this way, but only time will tell.

Also, does anyone know what boost level I SHOULD run? I think it's somewhere between 16-18 psi. BTW: I have no spiking, she goes to the dialed in boost level and slowly (slower than my J-valve) drops to redline, then shift and boosts again. That part is really nice.

BranCKY3
09-28-2005, 07:19 PM
How's the partial throttle?

TJHUB
09-28-2005, 08:23 PM
Functional but sensitive. I don't know that I would call it bad yet or not. It's different. I have the boost around 16 psi which makes it a little more tame than the 19 psi that I tried. I was out of town today so I didn't drive the car more than 4 miles since the install. Tomorrow is my day. I'll be driving around 60 miles. That should be enough to figure out if I can accept it or not.

greenz
09-28-2005, 08:26 PM
maybe you have cooked the 710N ?

Even w/ 40k stock miles and 3k chipped miles, i think i feel surge when the car is cold... Chip is only mod so far, so i'm looking into a new DV and MBC.

TJHUB
09-28-2005, 08:30 PM
I was thinking that, but I have NO surging at all with the MBC. I was thinking of doing some logs with my VAG to see just what the N75 was doing. Since the only change was the MBC, the N75 was obviously the issue. I don't understand why this would be, but it seems to be fact.

bitterchild
09-28-2005, 09:37 PM
the sound is the mbc bleeding off air as it's supposed to. I hope you left the n75 connector hooked up and routed the n75 to itself. Otherwise you probably have an n75 code.

goldenchild
09-28-2005, 11:22 PM
id set it to 19 psi if u r chipped atleast make it 18

BranCKY3
09-28-2005, 11:27 PM
I'll tell you now that you won't like the MBC alone. Partial throttle is way too touchy. Also with a K04 you should be setting it at 20 psi or so. Have you tried to just run a different N75 valve? I have a couple I can part with. I have a stock S4 valve "B" that worked great eliminating surging on my car.

goldenchild
09-29-2005, 05:35 AM
ya 20 psi if hes runing a big turbo file from giac if not id keep it at 18-19 psi

TJHUB
09-29-2005, 06:27 AM
Okay guys, I've got a couple of problems from just driving 25 miles to work this morning. BranCKY3, you are absolutely correct. The throttle is way too touchy. An extra 1/4" of depression on the throttle and you go from vacuum to BOOM...FULL BOOST. Even though the car doesn't rev up because it's barely getting any extra fuel.

I couldn't use my cruise this morning either. The car was bouncing back and forth between 7 In/Hg to 10 psi boost repeatedly because that's how sensitive my throttle is now. So I had to manually drive the car all the way to work. I was able to keep the car stable though without much effort. I also noticed that the turbo is whistling almost all the time on the Interstate at 75 mph. With the N75, I would hardly ever boost at that speed unless I depressed the throttle to pass or really accelerate.

I don't think I can keep this thing installed. The car is somewhat scarey to drive. I'm always worried I'm going to press that little bit too far and...BOOOST!

bitterchild: Yes I have my N75 installed in the intake with the pressure and output sides looped together (sealed) with a piece of tubing. It is also plugged in. I knew the ECU needed to see it, so I left in hooked up in this fashion.

BranCKY3: Thanks for the offer with the N75's. As mentioned above, I removed my N75J and reinstalled my stock N75C in anticipation of the MBC failure. I intend to test it to see if I still have the surging. I can't tell you how irritating the surging was getting. I hope my N75C works better than the J. I did a ton of research on how our turbos were controlled. I understood how an MBC would work and completely understood all of the posts you made about the MBC's being too touchy. Man you understated that! This thing is obnoxious. Going from vacuum to full boost in 1/4" of throttle travel...no way that's good.

bitterchild
09-29-2005, 06:41 AM
I like the whistling, it sounds like a siren : p

Burntaudi
09-29-2005, 06:53 AM
I would try the stock valve. I had the same surging problem running K04 software and a H valve. Putting the stock valve back in took care of it. I pretty much had the same experiance as you with running a MBC full boost felt nice but part throttle sucked.

Just currious have you tried lifting throttle when in full boost. My car would buck violently if I lifted throttle with a MBC.

TJHUB
09-29-2005, 07:23 AM
Burntaudi: Yes, mine does exactly that. It is violent if I lift at the wrong time. I also hope you're right about using the N75C. I will be a very happy guy if it works.

BranCKY3
09-29-2005, 09:13 AM
Yea I used a MBC for months by itself since my turbo was messed up. Wastegate was loose I guess and it only boosted to 10 psi, really annoying after buying a chip. I will never go back to using just a MBC.

Yeagy
09-29-2005, 09:55 AM
Do you mind taking a quick picture of what hoses you tapped for this MBC...ive searched but found nothing...thanks

BranCKY3
09-29-2005, 09:59 AM
Leave your N75 plugged into your intake pipe, but run a hose from the 2 open nipples on it, connecting them together. Then take the hose you unplugged off the left side of the N75, the nipple next to the intake nipple, and plug it in the bottom of the MBC. Then take the other hose coming off the N75 and put it on the other nipple on the MBC. Make sense?

TJHUB
10-01-2005, 06:47 AM
Burntaudi: and everyone else:

I took out the MBC and hooked up my stock N75C. The car has been silky smooth and runs great. No surging issues at all.

Looks like the N75J valve and the MBC are up for sale...

bitterchild
10-01-2005, 11:44 AM
I'll take the mbc.

TJHUB
10-01-2005, 12:59 PM
bitterchild: PM'd you.

bitterchild
10-01-2005, 01:52 PM
lol

Burntaudi
10-02-2005, 08:23 AM
Originally posted by TJHUB
Burntaudi: and everyone else:

I took out the MBC and hooked up my stock N75C. The car has been silky smooth and runs great. No surging issues at all.

Looks like the N75J valve and the MBC are up for sale...

Good to hear glad that it worked out.

Rosati
10-02-2005, 09:44 AM
So for a n75 newbie, What is the moral of this story?

I thought we were supposed to use mbc's as extra protection after The n75

bitterchild
10-02-2005, 12:15 PM
Originally posted by Rosati
So for a n75 newbie, What is the moral of this story?

I thought we were supposed to use mbc's as extra protection after The D/v?

an n75 is a boost controller, not a diverter valve. I diverter valve has nothing to do w/ boost control. diverter valves are commonly referred to as a 710, or 710N. MBCs can be hooked up in parallel to n75s to help control boost spikes while allowing the n75 to control all boost curves until the maximum setting on the mbc.

do you have an audi yet?

TJHUB
10-02-2005, 03:48 PM
Rosati: I think the moral of the story is that MBC hooked up stand alone doesn't work very well. The throttle and boost are way too touchy. While N75J valves are nice to bump up your boost a couple of psi on a K03, it's not so good on a K04 set up. I had no surging issues with the N75J until I upgraded to the K04 turbo and software. The surging was a real PITA. I don't know if what happened with my car would be the same for everyone's car, but there was a few on this thread that had it right.

Rosati
10-02-2005, 03:54 PM
Thank you .

I edited my post.

Due to a long night i wrote Diverter valve instead of N75 valve in my post

i apologize.

Kruat
10-02-2005, 04:30 PM
So how much boost do you see with the stock N75? I've been having the same issue with my N75J and KO4/GIAC, only it doesn't sound quite as bad as yours. I still think im running low boost for this setup thou, I only hit 16-18lbs. I thought I was suppose to hit 21lbs.

mike-2ptzero
10-02-2005, 04:43 PM
Originally posted by Kruat
So how much boost do you see with the stock N75? I've been having the same issue with my N75J and KO4/GIAC, only it doesn't sound quite as bad as yours. I still think im running low boost for this setup thou, I only hit 16-18lbs. I thought I was suppose to hit 21lbs.


What version chip are you running?

TJHUB
10-02-2005, 05:03 PM
Kraut: I hit about the same as you. It really hasn't been long enough for me to fully test, but 16-18 depending upon what gear I'm in. I peaked at 23 with the J valve in third gear a couple of times. Not that it really matters where you peak. I expect I will see a couple of 20 psi peaks if conditions are right.

Kruat
10-03-2005, 06:57 AM
Wow, I never hit above 19lbs.... I'm running whatever software is not the PC-16. I have stock injectors and a 5 bar.

But, I do know that my clutch slips, so I really don't push it that hard. But I was still expecting more boost. I went through and replaced all my vac lines. So, I dunno.

How much difference does elevation make on a turbo'd car? I am at 5000ft.

bitterchild
10-03-2005, 08:05 AM
you should have a little more boost pressure at 5000ft. Do you have any barometric pressure sensor codes? It's the little bugger in the ecu box

mike-2ptzero
10-03-2005, 08:18 AM
Originally posted by Kruat
Wow, I never hit above 19lbs.... I'm running whatever software is not the PC-16. I have stock injectors and a 5 bar.

But, I do know that my clutch slips, so I really don't push it that hard. But I was still expecting more boost. I went through and replaced all my vac lines. So, I dunno.

How much difference does elevation make on a turbo'd car? I am at 5000ft.

Higher elevations will make a big difference in power and a slight difference in boost readings. The reason is because thinner air heats up much faster when compressed and the hotter the air gets the more it expands. So this means less air is going to be pushed thru the turbo at a set boost level at 5000 ft vs sea level. Here in socal we can see a 30-40 g/s difference at the maf just going from sea level to 3000 ft. I have noticed this on my setup and on a chipped K03.

Kruat
10-03-2005, 12:28 PM
Thanks Mike, so, if I'm understanding what you said, I should have less boost at 5000ft then at sea level? Which would make sense, because since I've been here in AZ, I never saw the same boost levels on my KO3/Nospeed setup as I did in OR.

TJHUB
10-03-2005, 03:34 PM
Kruat: What does your exhaust tip look like on your Techtonics Borla? I'm looking to get a new exhaust, and I want to check into this one vs. the AWE version.

Thanks.

Kruat
10-03-2005, 10:18 PM
Yum, I don't know if I have pics, but it just duel 2.25" tips. But you can pick whatever tip you want from TT. The stock exhaust doesn't come with a tip.