How to tune your Electronic Boost Controller
09-14-2009, 03:35 PM
#1
How to tune your Electronic Boost Controller
Well; I finally decided to sit down and bang out some more info for everyone.
I did not get pics and video of the Boost Controller tuning I did in Seattle due to being distracted by dyno drama - but I think I can still get the gist out.
The first thing is to understand how a boost controller works; in simple terms it will hold back or modify the boost signal to the turbo wastegate to increase boost. Keep in mind that you can not go lower than your wastegate spring setting (except for an incorrectly set-up BC on an external wastegate). The issue with a factory wastegate spring set-up is that while the spring may be rated to say 10 PSI; that means the wastegate is fully open at 10 PSI; since it is operated by a diaphragm (mostly) the actuator arm will start to move much earlier than 10 PSI - as much as 5-6 PSI early it will have already cracked the wastgate and will be bleeding exhaust by the turbine a lot earlier than you want it to. If you want 10 PSI; then you want to get to 10 PSI as fast as possible without spiking the boost PAST 10 PSI.
Ok; so how can an EBC help us do this? Quite simply, you want to avoid sending ANY signal to the wastegate until the last possible moment. One of the typical faults of BC tuning is that people try to increase the overall amount of boost first - instead of setting up the starting boost threshold first.
So we know basically what we want to do - now how do we go about it?
MANUAL
One of the cheapest and easiest way's to increase the boost threshold is by making a mechanical change to the Wastegate and Actuator. By increasing the tension applied to the WG door - you can push the boost curve to the right (see picture); the shape of the curve will remain relatively the same. Swapping the Wastegate spring with a stiffer one (if applicable) will have similar effects. Ideally; you want the curve as close to the red line as possible. Manual Boost Controllers are IMO a waste of time and fairly un-tunable, so I won't discuss them here much; basically they do the same things as other manual methods of boost control...for more money.
ELECTRONIC
There are as many terms and settings as there are Electronic Boost Controllers; so read your instructions thoroughly; I'll use the terms for the Greddy series of EBC's. In most cases you have three BASIC settings; Start Boost, Gain and Set Boost. Each of these settings has an impact on your boost curve.
RULE 1: TUNE ONE SETTING AT A TIME!!! You cannot measure what changes were made if you are working with multiple variables. Tune one setting at a time until you get the best boost curve you can.
RULE 2: AIM SMALL; MISS SMALL!!! To avoid over boosting and wrecking your motor or turbo, make small changes as you progress and don't get impatient. This can take anywhere from 30-45 minutes to an entire day.
RULE 3: MEASURE EVERYTHING!!! If you cannot log your boost curve, then this exercise is useless; so get a boost gauge or log on your MAP based EMS curve... or SOMETHING!!! But you need to compare your boost curves as you tune.
Ok, on to the fun stuff.
Start Boost - this is the setting that controls how long your BC will send NO signal to the wastegate. IE; how long the wastegate will remain totally closed. This is the key setting for me.
Gain - Gain, or Duty Cycle or whatever; is how fast the solenoid on the BC will cycle, this is important because if your BC is cycling too slowly you can get boost fall off before it re-adjusts itself. Similarly, if the Duty Cycle is too high, you can get boost spikes.
Set - Set, Set Gain, Target Boost etc; is how high the BC will allow you to build pressure into the intake manifold by controlling the amount of signal boost being sent to the wastegate. This setting along with gain are what I tune together to fine tune the overall boost curve.
So; with my fully tuned vehicle in good mechanical order, I first ensure that I have enough fueling and headroom in my tune to get higher boost numbers. If not I make sure that I do... I NEVER tune a BC if I am on the ragged edge with just the Wastegate... a few pounds of boost is not worth a motor.
Then on a level, slightly inclined grade or dyno I begin tuning by getting a baseline boost curve from just the Wastegate. This will allow me to see what changes I am making to the curve.
Then I adjust the Start Boost until I peak at the target PSI, without going over... while it might look like a boost spike, it is not a spike UNLESS I overshoot my target boost. If I do, then I just need to lower the start boost level.
Once I have reached my target boost level; I then turn up the set value until I can hold the target boost level for as long as I can. The trick here is that IF I go past my target boost level I know my set value is too high, and the rest of my changes much be to the gain of the BC. Typically you see boost fade with all set and no gain.
Finally, add in my gain duty cycle to hold the boost level through the power band as best as possible.
In a nutshell that is about it. Now based on the size of your turbo and the trims, your curves will not look exactly the same (IE big turbo's take longer to spool no matter what). But the shapes are generally going to be correct. Also, if the compressor is too small - no matter what you may get boost fall off at high RPM.
If you have a low and high setting; or you are ready to increase your boost... use these "low" settings and adjust your set first to get your target boost, and then go back to start boost. This helps to avoid a boost spike if you are only making small changes to the target boost.
I did not get pics and video of the Boost Controller tuning I did in Seattle due to being distracted by dyno drama - but I think I can still get the gist out.
The first thing is to understand how a boost controller works; in simple terms it will hold back or modify the boost signal to the turbo wastegate to increase boost. Keep in mind that you can not go lower than your wastegate spring setting (except for an incorrectly set-up BC on an external wastegate). The issue with a factory wastegate spring set-up is that while the spring may be rated to say 10 PSI; that means the wastegate is fully open at 10 PSI; since it is operated by a diaphragm (mostly) the actuator arm will start to move much earlier than 10 PSI - as much as 5-6 PSI early it will have already cracked the wastgate and will be bleeding exhaust by the turbine a lot earlier than you want it to. If you want 10 PSI; then you want to get to 10 PSI as fast as possible without spiking the boost PAST 10 PSI.
Ok; so how can an EBC help us do this? Quite simply, you want to avoid sending ANY signal to the wastegate until the last possible moment. One of the typical faults of BC tuning is that people try to increase the overall amount of boost first - instead of setting up the starting boost threshold first.
So we know basically what we want to do - now how do we go about it?
MANUAL
One of the cheapest and easiest way's to increase the boost threshold is by making a mechanical change to the Wastegate and Actuator. By increasing the tension applied to the WG door - you can push the boost curve to the right (see picture); the shape of the curve will remain relatively the same. Swapping the Wastegate spring with a stiffer one (if applicable) will have similar effects. Ideally; you want the curve as close to the red line as possible. Manual Boost Controllers are IMO a waste of time and fairly un-tunable, so I won't discuss them here much; basically they do the same things as other manual methods of boost control...for more money.
ELECTRONIC
There are as many terms and settings as there are Electronic Boost Controllers; so read your instructions thoroughly; I'll use the terms for the Greddy series of EBC's. In most cases you have three BASIC settings; Start Boost, Gain and Set Boost. Each of these settings has an impact on your boost curve.
RULE 1: TUNE ONE SETTING AT A TIME!!! You cannot measure what changes were made if you are working with multiple variables. Tune one setting at a time until you get the best boost curve you can.
RULE 2: AIM SMALL; MISS SMALL!!! To avoid over boosting and wrecking your motor or turbo, make small changes as you progress and don't get impatient. This can take anywhere from 30-45 minutes to an entire day.
RULE 3: MEASURE EVERYTHING!!! If you cannot log your boost curve, then this exercise is useless; so get a boost gauge or log on your MAP based EMS curve... or SOMETHING!!! But you need to compare your boost curves as you tune.
Ok, on to the fun stuff.
Start Boost - this is the setting that controls how long your BC will send NO signal to the wastegate. IE; how long the wastegate will remain totally closed. This is the key setting for me.
Gain - Gain, or Duty Cycle or whatever; is how fast the solenoid on the BC will cycle, this is important because if your BC is cycling too slowly you can get boost fall off before it re-adjusts itself. Similarly, if the Duty Cycle is too high, you can get boost spikes.
Set - Set, Set Gain, Target Boost etc; is how high the BC will allow you to build pressure into the intake manifold by controlling the amount of signal boost being sent to the wastegate. This setting along with gain are what I tune together to fine tune the overall boost curve.
So; with my fully tuned vehicle in good mechanical order, I first ensure that I have enough fueling and headroom in my tune to get higher boost numbers. If not I make sure that I do... I NEVER tune a BC if I am on the ragged edge with just the Wastegate... a few pounds of boost is not worth a motor.
Then on a level, slightly inclined grade or dyno I begin tuning by getting a baseline boost curve from just the Wastegate. This will allow me to see what changes I am making to the curve.
Then I adjust the Start Boost until I peak at the target PSI, without going over... while it might look like a boost spike, it is not a spike UNLESS I overshoot my target boost. If I do, then I just need to lower the start boost level.
Once I have reached my target boost level; I then turn up the set value until I can hold the target boost level for as long as I can. The trick here is that IF I go past my target boost level I know my set value is too high, and the rest of my changes much be to the gain of the BC. Typically you see boost fade with all set and no gain.
Finally, add in my gain duty cycle to hold the boost level through the power band as best as possible.
In a nutshell that is about it. Now based on the size of your turbo and the trims, your curves will not look exactly the same (IE big turbo's take longer to spool no matter what). But the shapes are generally going to be correct. Also, if the compressor is too small - no matter what you may get boost fall off at high RPM.
If you have a low and high setting; or you are ready to increase your boost... use these "low" settings and adjust your set first to get your target boost, and then go back to start boost. This helps to avoid a boost spike if you are only making small changes to the target boost.
Last edited by Kane; 09-14-2009 at 04:01 PM.
09-14-2009, 04:31 PM
#8
Couple of things I'd like to add :
Gain : I've found that the gain setting has a large effect on boost overun . I set gain to the highest value I can that does not induce boost overun.
High rpm dropoff : Often not related to the boost controller in any way .
Some possible causes : undersized wastgate actuator , undersized turbine housing , undersized turbo or a combination of those.
Gain : I've found that the gain setting has a large effect on boost overun . I set gain to the highest value I can that does not induce boost overun.
High rpm dropoff : Often not related to the boost controller in any way .
Some possible causes : undersized wastgate actuator , undersized turbine housing , undersized turbo or a combination of those.
Last edited by Brettus; 09-14-2009 at 04:34 PM.
09-14-2009, 05:57 PM
#10
This is awesome stuff; i just wish it applied more to my ebc. I have the Gizzmo MS-IBC.
It has a duty cycle and a gain setting...also the ability to run in open loop or closed loop. Closed loop automatically adjusts the duty cycle in order to get a stable boost reading; open loop does not make changes to duty cycle.
I think how I have it setup is ok; I do get some boost creep but that is from the wg actuator. Brettus knows all about this...
I don't have a way to log my boost curve either, unless I am on a dyno.
Great info nonetheless Kane!
It has a duty cycle and a gain setting...also the ability to run in open loop or closed loop. Closed loop automatically adjusts the duty cycle in order to get a stable boost reading; open loop does not make changes to duty cycle.
I think how I have it setup is ok; I do get some boost creep but that is from the wg actuator. Brettus knows all about this...
I don't have a way to log my boost curve either, unless I am on a dyno.
Great info nonetheless Kane!
09-15-2009, 05:15 PM
#13
Thanks for the feedback guys.
Yeah there are a lot of other possible variables.. but for the most part this covers them. Some EBC's don't have a start boost - like the Blitz; but I noticed when the set value went up the boost curve went vertical - so I am guessing that they may have the start boost set-up automatic based on the set value.
Yeah there are a lot of other possible variables.. but for the most part this covers them. Some EBC's don't have a start boost - like the Blitz; but I noticed when the set value went up the boost curve went vertical - so I am guessing that they may have the start boost set-up automatic based on the set value.
09-15-2009, 11:40 PM
#14
A couple things:
You will read about different methods for tuning EBC's. Many of them call for adjusting the duty cycle first ("SET" on the Greddy Spec II), then the GAIN (if the EBC even has gain/closed loop), and then START BOOST last. Kane's way (START BOOST/"spring pressure"/whatever first) is as good as any; if anything, I kind of like it more. Sometimes you have to go back and make small changes after the initial tuning.
One thing that's important to note about the Greddy Spec II is that the units trip people up. START BOOST is configured as an actual boost value, and this can especially confuse people in psi mode where it is displayed in 3 digits. SET is configured as a % for the base solenoid duty cycle. GAIN is a % value as well--it's used in the closed loop correction of the solenoid duty, kind of like how closed loop fuel correction changes injector duty.
Now it's time to get technical.
All the EBC does is cycle the coil in the solenoid off and on (duty control) just like a fuel injector. On an internally wastegated turbo, the three-way solenoid valves normally used are configured as Normally Open (NO). When the solenoid coil is engaged, the pressure signal is essentially blocked. This diagram is actually a Perrin solenoid used as a replacement for the OEM Subaru solenoid. I've marked it up like the Denso solenoid used in many aftermarket external EBC's.
now with the solenoid coil engaged (kind of like when a fuel injector cycles on):
On external wastegates, the solenoid valve us configured as "NC" or Normally Closed. Instead of blocking air to the wastegate, more duty delivers more air to the top port of the external wastegate chamber to push the poppet valve closed.
This is the pressure at which the solenoid drops from max duty (95% or so) to a duty value near the SET value (taking into account closed-loop correction). So less pressure is being bled off from the wastegate diaphragm and the wastegate can open.
This sets a baseline duty value when the EBC is above the "START BOOST" pressure. This value is then modified by the closed-loop control behind the scenes in an effort to keep boost more stable. Be careful with the terms "SET GAIN" . Having SET and GAIN highlighted on the Spec II box is actually used to set the "START BOOST" . Confused yet? See the "START BOOST" section of the very first pic I posted.
Also, "Set" has nothing to do with target boost. It is a baseline duty cycle value. There are no target boost tables in the Profec EBC's. The Profec has no idea what boost you really want. It just uses calculus to determine whether the boost is falling off or not, so it can decide how much corrective action to take based on the rate the boost is changing and the gain parameters you have chosen. Other EBC's DO have target boost tables that are used for the closed-loop control logic. The Apex'i AVC-R comes to mind, and of course any closed-loop system on a standalone or a modern ECU equipped with a factory EBC (Subaru's for example).
Gain is a bunch of closed loop control logic all wrapped up into one setting. It probably sets coefficients for PID control (Proportional, Integral, Derivative). Google/wikipedia "Ziegler Nichols tuning." It also probably affects how much the boost is allowed to deviate (oscillations) and how much authority the closed loop has to change the solenoid duty from the base "SET" value.
Now I may blow somebody's mind here. Here is a log from my Rx-7 of solenoid duty vs boost and rpm over a 15ish psi run. I have pointed out which Profec/EBC settings correspond to which areas of the duty cycle curve in green. It illustrates how control logic on most external EBC's works using Profec Spec II terminology. A lot of the same basic settings are used in other EBC's (Blitz etc). Note that AEM Tru Boost does not have a gain function. It is a completely open-loop boost controller, with only a "set" and "start boost" style control.
You will read about different methods for tuning EBC's. Many of them call for adjusting the duty cycle first ("SET" on the Greddy Spec II), then the GAIN (if the EBC even has gain/closed loop), and then START BOOST last. Kane's way (START BOOST/"spring pressure"/whatever first) is as good as any; if anything, I kind of like it more. Sometimes you have to go back and make small changes after the initial tuning.
One thing that's important to note about the Greddy Spec II is that the units trip people up. START BOOST is configured as an actual boost value, and this can especially confuse people in psi mode where it is displayed in 3 digits. SET is configured as a % for the base solenoid duty cycle. GAIN is a % value as well--it's used in the closed loop correction of the solenoid duty, kind of like how closed loop fuel correction changes injector duty.
Now it's time to get technical.
All the EBC does is cycle the coil in the solenoid off and on (duty control) just like a fuel injector. On an internally wastegated turbo, the three-way solenoid valves normally used are configured as Normally Open (NO). When the solenoid coil is engaged, the pressure signal is essentially blocked. This diagram is actually a Perrin solenoid used as a replacement for the OEM Subaru solenoid. I've marked it up like the Denso solenoid used in many aftermarket external EBC's.
now with the solenoid coil engaged (kind of like when a fuel injector cycles on):
On external wastegates, the solenoid valve us configured as "NC" or Normally Closed. Instead of blocking air to the wastegate, more duty delivers more air to the top port of the external wastegate chamber to push the poppet valve closed.
Start Boost - this is the setting that controls how long your BC will send NO signal to the wastegate. IE; how long the wastegate will remain totally closed. This is the key setting for me.
Set - Set, Set Gain, Target Boost etc; is how high the BC will allow you to build pressure into the intake manifold by controlling the amount of signal boost being sent to the wastegate. This setting along with gain are what I tune together to fine tune the overall boost curve.
This sets a baseline duty value when the EBC is above the "START BOOST" pressure. This value is then modified by the closed-loop control behind the scenes in an effort to keep boost more stable. Be careful with the terms "SET GAIN" . Having SET and GAIN highlighted on the Spec II box is actually used to set the "START BOOST" . Confused yet? See the "START BOOST" section of the very first pic I posted.
Also, "Set" has nothing to do with target boost. It is a baseline duty cycle value. There are no target boost tables in the Profec EBC's. The Profec has no idea what boost you really want. It just uses calculus to determine whether the boost is falling off or not, so it can decide how much corrective action to take based on the rate the boost is changing and the gain parameters you have chosen. Other EBC's DO have target boost tables that are used for the closed-loop control logic. The Apex'i AVC-R comes to mind, and of course any closed-loop system on a standalone or a modern ECU equipped with a factory EBC (Subaru's for example).
Gain - Gain, or Duty Cycle or whatever; is how fast the solenoid on the BC will cycle, this is important because if your BC is cycling too slowly you can get boost fall off before it re-adjusts itself. Similarly, if the Duty Cycle is too high, you can get boost spikes.
Now I may blow somebody's mind here. Here is a log from my Rx-7 of solenoid duty vs boost and rpm over a 15ish psi run. I have pointed out which Profec/EBC settings correspond to which areas of the duty cycle curve in green. It illustrates how control logic on most external EBC's works using Profec Spec II terminology. A lot of the same basic settings are used in other EBC's (Blitz etc). Note that AEM Tru Boost does not have a gain function. It is a completely open-loop boost controller, with only a "set" and "start boost" style control.
Last edited by arghx7; 09-15-2009 at 11:58 PM.
09-16-2009, 01:00 AM
#15
At the top is an actual target boost table in units of atmospheres (1.0 would be 100kPA or 14.5psi). You can see from this stock Subaru AP tables how sophisticated OEM EBC's are. there are actually a lot more tables in the ECU than this. Hardly anyone uses external EBC's on Subarus because the factory EBC is so good.
01-31-2010, 07:52 PM
#20
I divide by zero
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Just just hooked mine up for the first time today. I dont think I should have a BC.....that little button to switch between profiles is way too tempting 
I just set my WG cracking to 6psi(WG is on 6.5 port). Boost setting A=33% gain gave me 8.5psi for daily driving. Boost setting B=75%-- 10.8psi Yeee haw! Had to try setting B just once
I just set my WG cracking to 6psi(WG is on 6.5 port). Boost setting A=33% gain gave me 8.5psi for daily driving. Boost setting B=75%-- 10.8psi Yeee haw! Had to try setting B just once
01-31-2010, 10:38 PM
#21
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has anyone used the Gizzmo-MS-IBC other then 05rex8?
im thinking of this or the greddy
any suggestions?
another question would moving the controller closer to the solinoid/turbo make for a safer operation or distance doesnt really matter?
im thinking of this or the greddy
any suggestions?
another question would moving the controller closer to the solinoid/turbo make for a safer operation or distance doesnt really matter?
Last edited by Talic; 01-31-2010 at 11:18 PM.
01-31-2010, 10:39 PM
#22
01-31-2010, 11:28 PM
#24
well I like it, it's very easy to use and set up
I never used the greddy so I can't really compare the two
I have used the AEM tru-boost and turbosmart E-boost (the first version) and I like the gizzmo the best
I never used the greddy so I can't really compare the two
I have used the AEM tru-boost and turbosmart E-boost (the first version) and I like the gizzmo the best
01-31-2010, 11:43 PM
#25
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how accurate is the boost guage on it? (i would assume very good or it cant do its job properly)
and about the line to the controller, would the distance matter on how far the controller is from the solinoid?
and about the line to the controller, would the distance matter on how far the controller is from the solinoid?