mechanics of boost control ..

[Breezy]

I understand that the MS3 has two boost control methods .. a diaphram type of pop off valve, and an electronic boost limiter.

Can anyone give me some idea of how I might find out enough detail to wire in a switch that will reduce boost for economy/criuse driving?

Ideally I would like to be able to toggle a switch in the interior and have the boost drop, I imagine by engaging the electronic controller, maybe like the boost being limited in 1st and 2nd gears.

Otherwise I guess I would be looking at a vacuum type adjustable boost controller which will require running vacuum lines in the interior or a solenoid under the hood.

Any ideas for me ?

Thanks

 

[07speed3]

I would suggest an EBC that way you can raise or lower as you please, the greddy profec 2 is a very nice unit.

 

[Breezy]

Certainly I guess that would work but it's like using a shotgun to kill a fly. I just wanted a switch that reduces boost or resets boost to factory settings. I'm thinking that either interupting the wire to the electronic control or feeding the voltage to the electronic control would be closest to what I want to acheive.

Keep in mind that I'm just trying to limit the boost coming in so strong, and running boost while cruising around 80 mph. Seems like anything north of 70 mph gets into the boost all the time.

 

[trufanatic]

Certainly I guess that would work but it's like using a shotgun to kill a fly. I just wanted a switch that reduces boost or resets boost to factory settings. I'm thinking that either interupting the wire to the electronic control or feeding the voltage to the electronic control would be closest to what I want to acheive.

Keep in mind that I'm just trying to limit the boost coming in so strong, and running boost while cruising around 80 mph. Seems like anything north of 70 mph gets into the boost all the time.

well if you want to get technical i've done something like this before but using the GM typhoon/syclone boost controle solenoid. most if no all boost solenoids work the same. 1 wire is ground, 1 is 0-12 volts which translates to 0-100%open = how much boost you'll get. first you'll have to figure if the stock BC uses an open or close configuration to bleed boost. Next, check the voltage with a meter on the 12v line and go WOT a couple times and see what is your max voltage for 15.6-18psi i guess because depending on weather we do spike. once you figure than out, get yourself a 12v dial and wire it inline with the power to the BS. When the dial is 0% and limiting voltage you should only get wastegate pressure which would only be 5-8 psi which isnt s***. I kno your goal, limiting or eliminating part throttle boost will have this car averaging 25+mpg minimum but good luck simply because this damn ecu is too smart for its own good. Get an EBC set you low boost to just above wastegate pressure and your high boost to whatever you want and take the ECU out of the equation....simple 200 bandaid.

 

[Breezy]

Yes, I agree that trying to fool the ecu is a bit tough. That's why buying a tuning tool like a boost controller or an accessport scares me. I don't want to blow the thing up, and the assumption with things is that you want MORE boost, therefore not much if any efforts to limit boost from the factory settings. Plus, that would void a warrantee in a heartbeat.

 

[trufanatic]

either way messing with boost will void the warranty, simply because the MAP reads volumetric pressure and the ECU will always log boost and the dealer can play that back. but for your own benefit and the best way not to throw a CEL, get a simple ebc with high and low boost so you can basically turn off or on your boost as you please. trust me, this ECU fights mods if it doesnt like em', lol ask CP-e

 

[Breezy]

So I was looking at your profile and you have a Greddy boost control, timer, and Greddy E manage. How much tuning have you had to do to get a benefit out of your setup, and I trust you're just trying to get more boost all the time? Do you ever tune for mileage?

 

[trufanatic]

i abondoned the project, it was fun though. but throttle on this car is all over the place. at idle sometime i'd see 4-5 %, while leisurely driving it would spike sometimes...really made me ask myself WTF. since i was using the e-01 to tune and it uses both rpm and tps voltage to tune i didnt want to have the hassle of this and a couple other issues but it worked fine, no problems. reason i chose the emangage is because i had 256 points to adjust fuel and tune. I really dont kno if im going to keep my speed, starting to think it wasnt the right platform for me so im going to see what parts come out the rest of this year, if nothing exciting happens its going bye bye.

 

[Bravnik]

All you would have to do if figure out how to put an electric on/off valve inline with the factory boost controller line.

When you install a MBC, you remove the factory controller vacuum line and cap off both ends. If this is all you did, then your car would run about 10PSI max boost as your running just off the wategate (please correct me if I'm wrong here).

I have a dual stage MBC. In the 1st stage it's factory boost (Max 10psi for the reason I stated above). In the 2nd stage its the boost setting I set it at (19psi in my case).

I installed the switch in the center storage box between the seats. If I use Valet or take it to get some work done, I simply turn the switch off. You could also use the low setting to get better gas mileage.

I have been monitoring my fuel consumption almost every tank. I drive about 70hwy 30city and I get 22-24mpg running 19PSI. Running low boost didn't net me any real mileage increase to be honest. The issue is staying out of boost not how much boost you do. If you keep your car in vacuum it will not really matter if your doing 5psi or 50psi.

 

[Breezy]

I have been monitoring my fuel consumption almost every tank. I drive about 70hwy 30city and I get 22-24mpg running 19PSI. Running low boost didn't net me any real mileage increase to be honest. The issue is staying out of boost not how much boost you do. If you keep your car in vacuum it will not really matter if your doing 5psi or 50psi.

Have you tried low boost at highway speeds? If so could you feel the difference when lightly accelerating, and again, no appreciable mpg increase? Also have you ever tested a full tank at low boost?

 

[matsuda]

I understand that the MS3 has two boost control methods .. a diaphram type of pop off valve, and an electronic boost limiter.

Can anyone give me some idea of how I might find out enough detail to wire in a switch that will reduce boost for economy/criuse driving?

Ideally I would like to be able to toggle a switch in the interior and have the boost drop, I imagine by engaging the electronic controller, maybe like the boost being limited in 1st and 2nd gears.

Otherwise I guess I would be looking at a vacuum type adjustable boost controller which will require running vacuum lines in the interior or a solenoid under the hood.

Any ideas for me ?

Thanks

It's very simple...

Disconnect the boost control solenoid valve and voila...
The boost pressure is at the minimum (approx. 10PSI on a stock MS3).

 

[Breezy]

It's very simple...

Disconnect the boost control solenoid valve and voila...
The boost pressure is at the minimum (approx. 10PSI on a stock MS3).

Simple .. That's what I want to hear! If I post a few pics of the underhood can you guide me to the wire connector we're talking about?

I'll do some extensive mileage tests and report back for everyone.

 

[mooserov]

Certainly I guess that would work but it's like using a shotgun to kill a fly. I just wanted a switch that reduces boost or resets boost to factory settings. I'm thinking that either interupting the wire to the electronic control or feeding the voltage to the electronic control would be closest to what I want to acheive.

Keep in mind that I'm just trying to limit the boost coming in so strong, and running boost while cruising around 80 mph. Seems like anything north of 70 mph gets into the boost all the time.

North of 70 mph, the only way to boost is to press the gas pedal. at cruising speeds you are at the very least 15 inches of vacuum. Get a cheap boost gauge to monitor this, or buy a dash hawk. Boost is a function of load and throttle. When cruising at a constant speed, the ecu is in closed loop mode. It is using the oxygen sensor to calculate the leanest possible mixture for fuel economy. At this speed in 6th(3000 rpm or so)the exhaust provides enough pressure to spin the turbocharger as soon as you load the engine by opening the throttle. The waste gate is there to prevent the engine from boosting all the time. The car is not IN boost, just ready to provide boost. It seems that way, i know, but it is really a fairly elegant vacuum controlled system.
Please correct me if I am wrong, I am still new to turbo cars.
Moose

 

[trufanatic]

North of 70 mph, the only way to boost is to press the gas pedal. at cruising speeds you are at the very least 15 inches of vacuum. Get a cheap boost gauge to monitor this, or buy a dash hawk. Boost is a function of load and throttle. When cruising at a constant speed, the ecu is in closed loop mode. It is using the oxygen sensor to calculate the leanest possible mixture for fuel economy. At this speed in 6th(3000 rpm or so)the exhaust provides enough pressure to spin the turbocharger as soon as you load the engine by opening the throttle. The waste gate is there to prevent the engine from boosting all the time. The car is not IN boost, just ready to provide boost. It seems that way, i know, but it is really a fairly elegant vacuum controlled system.
Please correct me if I am wrong, I am still new to turbo cars.
Moose

you got it down for the most part BUT.

you said "Boost is a function of load and throttle". 100%TRUE

but if you look at the rpm and throttle table and see where we create our boost, around 2800rpms and @ 70mph my car is just right above 3k and if i even minorly blip the gas while cruising or if i have the cruise on, ANY fluctuation of the throttle = part throttle boosting.

So i totally see where he's coming from and a boost controller wont totally fix this. simply because your cutting down the boost doesnt mean you can run lower than wastegate pressure so your still gonna have part throttle probs. if its bugging you can do two things. Get a bigger turbo or get an AWD turbo car (thought)

 

[matsuda]

Simple .. That's what I want to hear! If I post a few pics of the underhood can you guide me to the wire connector we're talking about?

I'll do some extensive mileage tests and report back for everyone.

Sorry that I don't have a picture but the boost control solenoid has a 2 pin connector (easy to disconnect), and 2 hoses. One hose is connected to the wastegate actuator and the other is connected to the plastic intake pipe.

 

[matsuda]

North of 70 mph, the only way to boost is to press the gas pedal. at cruising speeds you are at the very least 15 inches of vacuum. Get a cheap boost gauge to monitor this, or buy a dash hawk. Boost is a function of load and throttle. When cruising at a constant speed, the ecu is in closed loop mode. It is using the oxygen sensor to calculate the leanest possible mixture for fuel economy. At this speed in 6th(3000 rpm or so)the exhaust provides enough pressure to spin the turbocharger as soon as you load the engine by opening the throttle. The waste gate is there to prevent the engine from boosting all the time. The car is not IN boost, just ready to provide boost. It seems that way, i know, but it is really a fairly elegant vacuum controlled system.
Please correct me if I am wrong, I am still new to turbo cars.
Moose

For the most part you are correct except:

1) The oxygen sensors are used to maintain a stoichiometric A/F ratio during cruise which is necessary for optimum catalyst efficiency (i.e. lowest emissions).

2) The wastegate regulates the maximum boost pressure. It would normally be closed during cruise conditions and would start to open only under a moderate boost pressure.

 

[Breezy]

Sorry that I don't have a picture but the boost control solenoid has a 2 pin connector (easy to disconnect), and 2 hoses. One hose is connected to the wastegate actuator and the other is connected to the plastic intake pipe.

I'm pretty sure I know which connector it is, visable straight down from the top, between the battery?ECU box and the engine. From what I've been able to read, 12 volts closes the valve.

Actually after kicking it around a bit I wonder if a better approach would be to trick the ECU into thinking it's in first or second gear, with a rocker switch ot actuate it in the frontside of the shifter knob, so you can flip it instantly.

I'll be looking into that approach as well ..

 

[Bravnik]

Have you tried low boost at highway speeds? If so could you feel the difference when lightly accelerating, and again, no appreciable mpg increase? Also have you ever tested a full tank at low boost?

Oh you will notice the difference on low boost. You don't have to be on the highway to feel it. There is a huge difference.

I never run the low boost to notice any MPG difference. I like my high boost

 

[ElBartoRex]

the easiest way to do this is get a boost gauge and just stay out of boost...

how often are you running positive boost pressure when you are driving for economy/cruising?..never

 

[Breezy]

the easiest way to do this is get a boost gauge and just stay out of boost...

how often are you running positive boost pressure when you are driving for economy/cruising?..never

Actually anything over 70 mph and you're in the boost. And just take a drive and set your computer to instant MPG. Very little throttle at 70 drops mileage substantially. That's what I'm looking to fix. I want to cruise at low boost to save mileage.