# APR tune+manual boost controller, has anyone ever done it?



## unplugged92 (Jul 13, 2012)

2003 awp, apr stage one, stock turbo. Has anyone here ever tried putting a manual boost controller on a tuned 1.8t?

any opinions on it? Just pondering the thought of doing it


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## groggory (Apr 21, 2003)

lol


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## taverncustoms (Feb 18, 2011)

MBC or manual boost controllers are not good for APR tunes. just trust me on this.:wave:


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## groggory (Apr 21, 2003)

unplugged92 said:


> 2003 awp, apr stage one, stock turbo. Has anyone here ever tried putting a manual boost controller on a tuned 1.8t?
> 
> any opinions on it? Just pondering the thought of doing it


don't do it

n249 delete is good though


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## taverncustoms (Feb 18, 2011)

groggory said:


> don't do it
> 
> n249 delete is good though


X2 :thumbup:


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## Chickenman35 (Jul 28, 2006)

Edit: Probably won't work with DBW. You'll " usually " get massive surge. 

However..on an *AEB with DBC*, it works just dandy. On my daily driver I've use a MBC on my APR Stage 1 tune for several years. The gain in torque through the mid-range and bottom end is fantastic. I normally run 15 psi daily and crank it to 18psi for track days. Nothing special engine wise on this car, but it was quick enough to hold a couple of Lotus Exiges at bay during a local track day. 

I've played with running just the N75 by itself , N75 with MBC in parallel and MBC by itself. MBC by itself wins every time in fun factor and ease of driving. Just remember...I've got *DBC*. DBW is a whole different ballgame.


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## snubbs64 (Oct 23, 2004)

I gotta be honest, i don't know what these guys are talking about. On APR, i could never get my car to run right. Surging all over the place. Took it to the shop numerous times (APTuning) and no one could figure our the problem. Switched to GIAC X+, did the same thing but milder. Tried various hardware work-arounds, nothing i could do without simply lowering the boost with some of the anti-surging kits. The only thing that worked WAS running an MBC. You loose partial throttle boost control above ~6psi (goes to full boost), but you get solid boost and hold, plus you can up the boost beyond the software. The fueling and all that will be good, but the turbo will not last on significantly increased boost levels beyond the software spec. There is a give and take with this setup. I'd suggest getting yourself a cheap ball and spring boost controller and try it for yourself, see if you like it. If not, pop it off and sell it to a friend. I encountered what i BELIEVE these fellas are talking about and to me it was worth the trade off and was easy to adapt to so in the end there really wasnt one for me.

Try it, form your own opinion, but there are the effects, not just "trust me, don't do it!"...

BTW, this experience was on a 2003 AWP DBW, just like the OP's


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## Chickenman35 (Jul 28, 2006)

What normally happens on a DBW when you run a MBC ( as a standalone..not in parallel or " overboost " mode ), is that the actual boost can exceed the "requested " boost by a large amount. When this happens you get the surging as the ECU tries to compensate by dialing back the throttle while the MBC keeps trying to boost. ( Edit: You may have to do an N249 delete as well, as the ECU will also open the DV via the N249 if actual boost exceeds requested boost by too big of an amount ).

Now this all depends on how the ECU is tuned. If one tuning manufacturer allows a greater spread between requested boost and actual boost, then the surging may not occur.

Most people do report surging when running a MBC and DBW, from historical posts on this forum. There is always the exception though, as Snubbs 64 mentioned...so it may be worth trying. :beer:

Note: Edited my first reply as Snubbs64 made a good point. about his setup working against the normal Status Quo.


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## Scigano (Mar 10, 2011)

What is it about the Drive by Cable cars and their ECU that makes it more agreeable to MBCs?

I know the oldest of 1.8T A4s have a barometric pressure sensor instead of a MAP sensor.

Anything else help it function better w/ a MBC?


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## Slimjimmn (Apr 8, 2006)

unplugged92 said:


> 2003 awp, apr stage one, stock turbo. Has anyone here ever tried putting a manual boost controller on a tuned 1.8t?
> 
> any opinions on it? Just pondering the thought of doing it


Only run a MBC in line with the factory n75 to limit surging and limp mode from boost spikes. 
don't remove the factory n75 and install a mbc.


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## Chickenman35 (Jul 28, 2006)

Scigano said:


> What is it about the Drive by Cable cars and their ECU that makes it more agreeable to MBCs?
> 
> I know the oldest of 1.8T A4s have a barometric pressure sensor instead of a MAP sensor.
> 
> Anything else help it function better w/ a MBC?


With DBW. the ECU is constantly adjusting the throttle blade due to various parameters ( load factor being a big one ). Your foot can apply 75% throttle but the ECU may decide to open the throttle 50%...or it may go 100%. With load factors the MBC and ECU can start fighting each other...thus you get surging.

With DBC the ECU has no control over the throttle blades. WYSIWYG...your foot controls the throttle blade with no " VooDoo Magic " interfering. :laugh:


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## Scigano (Mar 10, 2011)

I always thought it was because the small-frame turbos respond _way_ too quickly to throttle inputs. When it goes — it goes the distance. 

Unless you wanted to always slowly roll onto the throttle — what I had to do when I tried a MBC for a bit — you were always going to over boost. I thought the N75 was there to kill the spike when you didn't need it so boost pressure could be built up progressively and predictably (like a bigger turbo does) at part throttle.

When people go big turbo, DBW or not, they chuck the N75 and use a MBC (or other boost controller). I just thought the N75 was a necessity for taming the. "jumping bean" turbo.


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## Marcus_Aurelius (Mar 1, 2012)

I have a DBW car and have taken the stock turbo to hell and back. I've ran with the N75 alone --> N75 with two MBC (one for boost ceiling and one to tailor boost onset) --> MBC as a standalone with N75 deleted. I can say that the MBC by itself is the best way to control boost period (car behaves like stock until the right pedal is pinned to the flor, with zero surging). MBC in tandem or standalone are not an issue with DBW cars. 

The problem is usually the preset boost limits in the ECU and the spoilers like the N249 crap. Even if tuned/flashed, if the ECU boost limits aren't raised enough, you'll run into issues as the ECU will fight to correct (especially at onset when the small frame snail can shoot to the moon). People just want their cake and eat it too, but don't truly understand the inner workings of mechanical boost control. You can't ask a single mechanical ball and spring to boost 25 psi (ceiling) and give you slow gradual roll into boost as a solenoid, bleeder valve, pneumatic valve would, it just doesn't happen. In my case, when I still ran the N75, I had to have two MBC to tailor onset to my liking and the second one to cap boost (a dual duty pneumatic valve like the boost machine would have worked too but didn't have the kind of control range I was looking for). If you want smooth, tame, gradual and numb boost profile at onset, use a bleeder type MBC. A ball sitting on a linear spring don't behave like that...


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## Chickenman35 (Jul 28, 2006)

Marcus_Aurelius said:


> I have a DBW car and have taken the stock turbo to hell and back. I've ran with the N75 alone --> N75 with two MBC (one for boost ceiling and one to tailor boost onset) --> MBC as a standalone with N75 deleted. I can say that the MBC by itself is the best way to control boost period (car behaves like stock until the right pedal is pinned to the flor, with zero surging). MBC in tandem or standalone are not an issue with DBW cars.
> 
> The problem is usually the preset boost limits in the ECU and the spoilers like the N249 crap. Even if tuned/flashed, if the ECU boost limits aren't raised enough, you'll run into issues as the ECU will fight to correct (especially at onset when the small frame snail can shoot to the moon). People just want their cake and eat it too, but don't truly understand the inner workings of mechanical boost control. You can't ask a single mechanical ball and spring to boost 25 psi (ceiling) and give you slow gradual roll into boost as a solenoid, bleeder valve, pneumatic valve would, it just doesn't happen. In my case, when I still ran the N75, I had to have two MBC to tailor onset to my liking and the second one to cap boost (a dual duty pneumatic valve like the boost machine would have worked too but didn't have the kind of control range I was looking for). If you want smooth, tame, gradual and numb boost profile at onset, use a bleeder type MBC. A ball sitting on a linear spring don't behave like that...


Eggxactly :thumbup: You and I are on the same wavelenghth here Max. There is a big difference on how a MBC is plumbed ( standalone or in parallel with N75 as overboost protection ) and whether a B&S or bleeder type is used. I think some people may be missing that point. I don't have one to compare...but I think DBC cars may be more forgiving with the on/off nature of a B&S MBC. DBW cars need a slower and flatter curve as supplied by a bleeder type or B&S with bleeder combo. Is that theory correct Max?

An " educated " right foot is also required with small frame turbo's :laugh: I do love the instant response of my B&S MBC ( standalone..no N75 controller )...but I do keep the boost ( usually ) under 18 psi ( Meh..it's a near stock DD ) for turbo life. That being said, I can build 18 - 20psi by about 2,800- 2900 rpm if conditions are right. The bottom end torque is awesome for Autocross :thumbup:


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## Scigano (Mar 10, 2011)

No doubt, the turbo response is raw at WOT, but the part-throttle driveability became apple sauce. This was w/ a stand alone Forge ball and spring MBC (before I went back to the N75).

Perhaps part-throttle would have been better had I tried a bleeder type. I like the way the N75 makes driving the spool-crazy software as effortless as the bigger, lazier turbo guys enjoy.

Before, I was always thinking and sweating before applying throttle, watching my RPMs, making sure to not be in too-high a gear.

Now I can just drive n' enjoy my car.


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## Marcus_Aurelius (Mar 1, 2012)

Chickenman35 said:


> Eggxactly :thumbup: You and I are on the same wavelenghth here Max. There is a big difference on how a MBC is plumbed ( standalone or in parallel with N75 as overboost protection ) and whether a B&S or bleeder type is used. I think some people may be missing that point. I don't have one to compare...but I think DBC cars may be more forgiving with the on/off nature of a B&S MBC. DBW cars need a slower and flatter curve as supplied by a bleeder type or B&S with bleeder combo. Is that theory correct Max?


Yes, that is my thought based on what I experienced playing with various combinations of boost control. A single bleeder type (standalone or mounted in tandem with the factory N75) goes a long way at taming boost onset and providing smoother, more gradual roll into boost if that's your cup of tea. Same way I also think that dual signal pneumatic valves (or running a pair of MBC with the N75) allow great control with an ability to independently control onset and boost ceiling. 

Regardless, I really think there is a trend here with FWD 1.8t cars. The majority of complaints and issues regarding part-throtle and boost onset control are from front wheel drivers where traction is also a factor. They want to set a higher than factory boost ceiling but also fear the on/off nature of how a ball and spring functions due to their traction limitations. I hang out quite a bit more in the AWD circles, and those complaints seems almost nonexistent since the superior traction allows a lot more flexibility and aggressiveness in the boost curve. People miss the point that a single ball and spring MBC is almost like an on/of switch, where pressure is denied to the wastegate actuator until a preset pressure exceeding the MBC spring rate is reached. This will always make for aggressive onset of boost since it's basically untamed until the spring cracks open in a non-linear fashion (there is no way around it, unless a different device or a pair of devices to tailor onset and ceiling separately). IMO, the bulk of regular Joes looking to control boost with a FWD will benefit from an EBC type controller which works on duty cycle and allow more gradual pressure signal to the wastegate actuator (N75 works in that fashion but is limited when working outside of factory boost range). :beer:


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## Chickenman35 (Jul 28, 2006)

Pretty much sums it up. The AWD vs FWD is also a big factor as you state. I LUV my AWD :beer:


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## Chickenman35 (Jul 28, 2006)

Often people mention running a MBC " inline " with an N75 control over-boost or boost spikes. What is sometimes missed is that the MBC must be installed correctly ( in parallel ) with the N75 valve or the system will not work properly.


Mainly for noobies benefit > Here is the correct way to install an MBC with an N75 to control overboost. Also in FAQ:










Normal standalone MBC installation ( No N75 control. N75 has to be resistored out or still connected electrically, but not physically ):


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## Chickenman35 (Jul 28, 2006)

Again, mainly for newbies >

Here is a picture of boost curves running the three different methods... N75 only, N75 with MBC in over-boost mode and MBC only.

( Note..picture not entirely correct, as with a stock or smallish turbo, the MBC by itself will normally build boost faster ( B&S type ) than N75. Normally the N75 slope is not this fast )

Edit: Original picture not hosted anymore. Found this one but it's a bit fuzzy.


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## unplugged92 (Jul 13, 2012)

lots of valuable information, thank you all!


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## Slimjimmn (Apr 8, 2006)

Grogg should FAQ this


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## groggory (Apr 21, 2003)

Slimjimmn said:


> Grogg should FAQ this


FAQ'd


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## teamx (Mar 6, 2011)

I love this forum. I was looking for exactly this info. Toying with the idea of using a Turbosmart MBC on my Unitronic Stg2 Ibiza Cupra but had no idea how to connect it.


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## Scigano (Mar 10, 2011)

teamx said:


> I love this forum. I was looking for exactly this info. Toying with the idea of using a Turbosmart MBC on my Unitronic Stg2 Ibiza Cupra but had no idea how to connect it.


How do you like Unitronic's Stage 2? Did you have 1+ before, b/c I do now n' wanted to know if the power increase comes at the expense of smoothness at all? I'm considering getting Stage 2.
1+ has delivery IMO as smooth as glass — totally stock-like at part throttle, reigning in the boost spike immediately.


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## teamx (Mar 6, 2011)

Scigano said:


> How do you like Unitronic's Stage 2? Did you have 1+ before, b/c I do now n' wanted to know if the power increase comes at the expense of smoothness at all? I'm considering getting Stage 2.
> 1+ has delivery IMO as smooth as glass — totally stock-like at part throttle, reigning in the boost spike immediately.


The Stage 2 file is awesome, super smooth as well, in terms of drivability its drives like stock car. Powe on the other hand is anything but stock 
If you already have additional hardware I'd say upgrading to stage2 is a no brainer


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## Scigano (Mar 10, 2011)

teamx said:


> The Stage 2 file is awesome, super smooth as well, in terms of drivability its drives like stock car. Powe on the other hand is anything but stock
> If you already have additional hardware I'd say upgrading to stage2 is a no brainer


Just noticed that your Ibiza Cupra was an '07 — I didn't know the 20V 1.8T was still used by SEAT into that year. I thought they switched to the FSI/TSI engines (I'm in the U.S. — where we don't get the other VAG cars).


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## teamx (Mar 6, 2011)

The SEAT IBiza uses the same platform as the VW Polo. Both the Ibiza Cupra and the Polo GTi was released with the 20vT motors. The SEAT Leon which shares the VW Golf platform and those were released with FSi and TFSi motors depending on model etc. Unfortunately SEAT as a brand pulled out of South Africa in late 2008 so we didn't get any newer models and engine packages


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## SickAzzGTI (Jul 10, 2012)

Chickenman35 said:


> Often people mention running a MBC " inline " with an N75 control over-boost or boost spikes. What is sometimes missed is that the MBC must be installed correctly ( in parallel ) with the N75 valve or the system will not work properly.
> 
> 
> Mainly for noobies benefit > Here is the correct way to install an MBC with an N75 to control overboost. Also in FAQ:
> ...


*NEITHER OF THESE WORK!!!! Atleast they didn't for ME!* I tried BOTH methods!! What gives? Couldn't get over 7 PSI with a MBC!!!!


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## Chickenman35 (Jul 28, 2006)

SickAzzGTI said:


> *NEITHER OF THESE WORK!!!! Atleast they didn't for ME!* I tried BOTH methods!! What gives? Couldn't get over 7 PSI with a MBC!!!!


What gives? You've got something wrong. Not trying to be funny but you have to give us a bit more info. Can you take some pictures of your setup? 

*7 PSI is the default spring pressure of the WG internal spring.* Gives you a clue about diagnostic procedures. IE: Most likely you are getting pressure supplied through the boost control line directly to the wastegate. Items #2,#3 and #4 most likely problem. 

Some things to check.

1: 7 PSI is also limp mode. Can you post a VAG-SCOM scan and clear codes? If not disconnect the battery for 10 minutes to clear codes. Normal warning about having Radio Code handy applies.

Edited after I read your signature with mods. ( N249 delete and Aftermarket tune ), so N249 dumping boost via DV is not possible.


2: Check your hose routing carefully. The boost line from the Turbo has to feed into the bottom end of the MBC, opposite the adjusting screw. Don't laugh... I've made this simple mistake myself. Hoses running every which way and late at night. S**T happens :beer:

3: *Here's a tricky one that will drive you NUTS.* A MBC has to have a small vent hole...after the check ball. It's either in the body...or here's the tricky part...drilled into the outlet fitting ( for threaded in brass fittings as in Diagram B). Get the inlet and outlet fittings mixed up, or swap the supplied outlet fitting for a regular brass fitting for fitting purposes ( like a 90 or 45 degree fitting ), and you are going to have this issue. Why? Because without that vent hole, the boost line to the Wastegate will pressurize, then the wastegate will stay open because the WG canister can't vent. The ball in the MBC will act as a one way check valve. Not an issue with bleed style MBC's...but this vent hole must be there for a B&S MBC to work.

4: Defective MBC. Take it apart and check that the ball is seating properly. All it takes is a bit of machining swarf ( debris ) to hold the ball off it's seat and then boost won't build properly. I went as far as lapping the ball and the seat together with valve grind lapping compound to make a perfect seal. A bit Anal..but effective. If the MBC is used, it can also get " gummed " up with oil. Occasionally you have to clean them out with some Brake Clean. Worn out turbo's can make this a regular maintenance job.

Hope this helps. Post back with results please. :wave: :beer:


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## Chickenman35 (Jul 28, 2006)

SickAzzGTI: Here's something I just noticed. You have an ATP tune? I believe that is a Mika tune...which generally does not get good reviews around here from what I've read. 

One possibility is that the Tune doesn't have much " over head " programmed in for over boosting. So if you ran the MBC by itself, and boosted higher than the software allowed, then it may have thrown the ECU into Limp Mode. Just a thought...but it may be something to double check.

Edit: Probably going to turn out to be something really simple..and you'll do a WTF moment!! :laugh:


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## SickAzzGTI (Jul 10, 2012)

It def was a "wtf moment".....

.... the ball and spring were backwards!!!!! Lol! It works!


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## Gonzzz (Apr 27, 2010)

:facepalm:


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## SickAzzGTI (Jul 10, 2012)

That's how it was shipped to me! Figured they would have ATLEAST shipped it the way it was SUPPOSED to be installed... guess I was WRONG!!!

... Nonetheless, I took it off! It was a cheapo MBC and just didn't help at ALL! I'm going to get a better one after I get my clutch thrown in, to help a little with boost spikes! 

Great info here tho, both diagrams work regarding keeping the N75 or bypassing it all together...:thumbup:


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## Chickenman35 (Jul 28, 2006)

A very good article at BoostController.com on different types of MBC's and how thye operate:

http://www.boostcontroller.com/display_page.php?i=19


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## SickAzzGTI (Jul 10, 2012)

Chickenman35 said:


> A very good article at BoostController.com on different types of MBC's and how thye operate:
> 
> http://www.boostcontroller.com/display_page.php?i=19


:thumbup:


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