Boost hits hard then drops immediately
02-21-16, 10:47 PM
#1
Boost hits hard then drops immediately
Hey guys,
Wondering what your input would be on this...
Roll on 3rd gear, or really any gear for that matter and around 4,000-4,500 rpm's the boost comes in nice and strong 14-15 pounds and instantly drops from there to anywhere between 8-10 pounds.
I've played with the boost controller and no changes. Using a Greddy Profec B Spec II, here are my settings:
SET: 25%
GAIN: 35% (Max)
START BOOST: 150
I haven't tried getting more aggressive with the SET percentage cause I don't want to show my motor 17 or 20 pounds by mistake. The GAIN is completely maxed out, and I don't think the other setting has much to do with holding boost.
Turbo is a 60-1 size turbo or there abouts (unsure of specifics...) with a 3" downpipe and 50mm wastegate recirculated into exhaust. Running a resonated mid-pipe and a PFS cat-back.
Any advice would be appreciated. Some have suggested that it's too much back pressure but I want to say I've seen guys on these boards who weren't running dump tubes and still holding 15 pounds...?
Your thoughts gentlemen?
Thanks!
Nick
Wondering what your input would be on this...
Roll on 3rd gear, or really any gear for that matter and around 4,000-4,500 rpm's the boost comes in nice and strong 14-15 pounds and instantly drops from there to anywhere between 8-10 pounds.
I've played with the boost controller and no changes. Using a Greddy Profec B Spec II, here are my settings:
SET: 25%
GAIN: 35% (Max)
START BOOST: 150
I haven't tried getting more aggressive with the SET percentage cause I don't want to show my motor 17 or 20 pounds by mistake. The GAIN is completely maxed out, and I don't think the other setting has much to do with holding boost.
Turbo is a 60-1 size turbo or there abouts (unsure of specifics...) with a 3" downpipe and 50mm wastegate recirculated into exhaust. Running a resonated mid-pipe and a PFS cat-back.
Any advice would be appreciated. Some have suggested that it's too much back pressure but I want to say I've seen guys on these boards who weren't running dump tubes and still holding 15 pounds...?
Your thoughts gentlemen?
Thanks!
Nick
02-21-16, 11:36 PM
#2
Hi Nick, here are my thoughts.
Too much back pressure. You have not said what size spring you have in your wastegate, but it's definitely that. I know you are unsure about your turbo size, but the specifics of the turbo (compressor size, turbine trim, A/R, etc) will help greatly.
Try this. Disconnect your wastegate line entirely. Get up to 5000 rpms nice and gentle like, then nail the throttle. I'm hoping that it will stay at or below 16psi at first, but if it drops like a stone, it's definitely backpressure pushing the wastegate open. You may have to up the spring size. Now if the spring is, say 13-14 lbs and it's dropping that far down to 8-10 lbs, you gotta find out why you have so much backpressure.
The thing with turbos is that there is a pressure ratio on the exhaust size that determines your backpressure as well. The more exhaust back pressure you have post turbo, determines the amount of pressure pre-turbo. So even as low as 1-2 psi of backpressure will cause upwards of 15-20 psi preturbine pressure, shoving the wastegate open.
I'll link a fantastic article about turbo maps and how to read them, I'll also link the Borg Warner Match-Bot site. It shows in detail how just a tiny bit of post-turbo pressure can make a huge impact.
Hopefully you get this figured out. Many other members have issues keeping boost from creeping, so at least you are on the good side here, safety-wise that is.
The Match-Bot tool does not apply very well to rotary engines, unless you plug in the numbers correctly. I honestly have only used the tool to calculate theoretical engine configurations and as a learning tool.
-Ian
Turbo Tech: Compressor and Turbine Map Details
Performance Turbos | BorgWarner Turbo Systems
Too much back pressure. You have not said what size spring you have in your wastegate, but it's definitely that. I know you are unsure about your turbo size, but the specifics of the turbo (compressor size, turbine trim, A/R, etc) will help greatly.
Try this. Disconnect your wastegate line entirely. Get up to 5000 rpms nice and gentle like, then nail the throttle. I'm hoping that it will stay at or below 16psi at first, but if it drops like a stone, it's definitely backpressure pushing the wastegate open. You may have to up the spring size. Now if the spring is, say 13-14 lbs and it's dropping that far down to 8-10 lbs, you gotta find out why you have so much backpressure.
The thing with turbos is that there is a pressure ratio on the exhaust size that determines your backpressure as well. The more exhaust back pressure you have post turbo, determines the amount of pressure pre-turbo. So even as low as 1-2 psi of backpressure will cause upwards of 15-20 psi preturbine pressure, shoving the wastegate open.
I'll link a fantastic article about turbo maps and how to read them, I'll also link the Borg Warner Match-Bot site. It shows in detail how just a tiny bit of post-turbo pressure can make a huge impact.
Hopefully you get this figured out. Many other members have issues keeping boost from creeping, so at least you are on the good side here, safety-wise that is.
The Match-Bot tool does not apply very well to rotary engines, unless you plug in the numbers correctly. I honestly have only used the tool to calculate theoretical engine configurations and as a learning tool.
-Ian
Turbo Tech: Compressor and Turbine Map Details
Performance Turbos | BorgWarner Turbo Systems
02-22-16, 06:38 AM
#4
Hi Nick, here are my thoughts.
Too much back pressure. You have not said what size spring you have in your wastegate, but it's definitely that. I know you are unsure about your turbo size, but the specifics of the turbo (compressor size, turbine trim, A/R, etc) will help greatly.
Try this. Disconnect your wastegate line entirely. Get up to 5000 rpms nice and gentle like, then nail the throttle. I'm hoping that it will stay at or below 16psi at first, but if it drops like a stone, it's definitely backpressure pushing the wastegate open. You may have to up the spring size. Now if the spring is, say 13-14 lbs and it's dropping that far down to 8-10 lbs, you gotta find out why you have so much backpressure.
The thing with turbos is that there is a pressure ratio on the exhaust size that determines your backpressure as well. The more exhaust back pressure you have post turbo, determines the amount of pressure pre-turbo. So even as low as 1-2 psi of backpressure will cause upwards of 15-20 psi preturbine pressure, shoving the wastegate open.
I'll link a fantastic article about turbo maps and how to read them, I'll also link the Borg Warner Match-Bot site. It shows in detail how just a tiny bit of post-turbo pressure can make a huge impact.
Hopefully you get this figured out. Many other members have issues keeping boost from creeping, so at least you are on the good side here, safety-wise that is.
The Match-Bot tool does not apply very well to rotary engines, unless you plug in the numbers correctly. I honestly have only used the tool to calculate theoretical engine configurations and as a learning tool.
-Ian
Turbo Tech: Compressor and Turbine Map Details
Performance Turbos | BorgWarner Turbo Systems
Too much back pressure. You have not said what size spring you have in your wastegate, but it's definitely that. I know you are unsure about your turbo size, but the specifics of the turbo (compressor size, turbine trim, A/R, etc) will help greatly.
Try this. Disconnect your wastegate line entirely. Get up to 5000 rpms nice and gentle like, then nail the throttle. I'm hoping that it will stay at or below 16psi at first, but if it drops like a stone, it's definitely backpressure pushing the wastegate open. You may have to up the spring size. Now if the spring is, say 13-14 lbs and it's dropping that far down to 8-10 lbs, you gotta find out why you have so much backpressure.
The thing with turbos is that there is a pressure ratio on the exhaust size that determines your backpressure as well. The more exhaust back pressure you have post turbo, determines the amount of pressure pre-turbo. So even as low as 1-2 psi of backpressure will cause upwards of 15-20 psi preturbine pressure, shoving the wastegate open.
I'll link a fantastic article about turbo maps and how to read them, I'll also link the Borg Warner Match-Bot site. It shows in detail how just a tiny bit of post-turbo pressure can make a huge impact.
Hopefully you get this figured out. Many other members have issues keeping boost from creeping, so at least you are on the good side here, safety-wise that is.
The Match-Bot tool does not apply very well to rotary engines, unless you plug in the numbers correctly. I honestly have only used the tool to calculate theoretical engine configurations and as a learning tool.
-Ian
Turbo Tech: Compressor and Turbine Map Details
Performance Turbos | BorgWarner Turbo Systems
The turbo is most likely similar to a 60-1, I'm guessing. I'm going to text the previous owner to try and verify. He told me originally it was a GT40 but there's absolutely no markings on the cold side of the turbo. Also, the outlet is only 3" so I know it can't be a GT40.
If I were to run a dump tube off the wastegate instead of recirculating like it is now, do you think that would solve the issue all together?
Thanks!
Nick
Last edited by Brilliant7-LFC; 02-22-16 at 06:43 AM.
02-22-16, 06:41 AM
#5
Nick
02-22-16, 06:45 PM
#6
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I have had similar issues of building boost to 18psi then dropping to 11psi, found a leak in an intercooler coupler, replaced it and ran 18psi all day long, then it started happening again and found a coupler clamp loose and it was leaking out of there, retightened it and was back to full boost again. Just an idea
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02-25-16, 10:16 AM
#10
Rotary Enthusiast
I think it could be the settings on your controller. Happened to me with my Eboost2 some time back. I was telling it to hit 16psi but there was a safety setting where if it went above 12psi it would revert back down to 8psi. I didn't know of this setting so I kept looking for a problem for months until I figured it out. It felt exactly as you describe. Worth a look imo.
Good luck!
Chris
Good luck!
Chris
02-28-16, 08:38 AM
#11
backpressure could be a factor, yes, and you should always check for exhaust leaks and compressor side leaks. Pressurize your system with a boost leak pressure tester (simple pvc cap and air fitting - Boostpro.net : Products - Boost Leak Testers , universal tester).
After you check for leaks the boost control settings are where you need to go next. I see a lot of areas of concern in the way you have it set.
In a few words, your **** is jacked.
You didn't specify what units you are set to. If you are in PSI, your start boost is set to 15psi. If you are in kPa, your start boost is set to 21psi. It's a big difference.
What's most likely happening is that your wastegate is completely shut until the start boost pressure is reached, then the commanded duty cycle (SET%) is too low, and your gain is trying to overcompensate because it's maxed. You are passing through the Start boost setpoint and there's some kind of hysteresis or other thing going on. Then you have to shift before it can build up boost again through closed loop feedback.
If you don't know what I'm talking about you need to read this thread:
https://www.rx7club.com/3rd-generati...-chart-952767/
then set every boost controller setting to the minimum and start tuning it all over again. This image is in the thread:
After you check for leaks the boost control settings are where you need to go next. I see a lot of areas of concern in the way you have it set.
SET: 25%
GAIN: 35% (Max)
START BOOST: 150
I haven't tried getting more aggressive with the SET percentage cause I don't want to show my motor 17 or 20 pounds by mistake. The GAIN is completely maxed out, and I don't think the other setting has much to do with holding boost.
GAIN: 35% (Max)
START BOOST: 150
I haven't tried getting more aggressive with the SET percentage cause I don't want to show my motor 17 or 20 pounds by mistake. The GAIN is completely maxed out, and I don't think the other setting has much to do with holding boost.
You didn't specify what units you are set to. If you are in PSI, your start boost is set to 15psi. If you are in kPa, your start boost is set to 21psi. It's a big difference.
What's most likely happening is that your wastegate is completely shut until the start boost pressure is reached, then the commanded duty cycle (SET%) is too low, and your gain is trying to overcompensate because it's maxed. You are passing through the Start boost setpoint and there's some kind of hysteresis or other thing going on. Then you have to shift before it can build up boost again through closed loop feedback.
If you don't know what I'm talking about you need to read this thread:
https://www.rx7club.com/3rd-generati...-chart-952767/
then set every boost controller setting to the minimum and start tuning it all over again. This image is in the thread:
Last edited by arghx; 02-28-16 at 08:43 AM.
02-28-16, 10:37 PM
#12
backpressure could be a factor, yes, and you should always check for exhaust leaks and compressor side leaks. Pressurize your system with a boost leak pressure tester (simple pvc cap and air fitting - Boostpro.net : Products - Boost Leak Testers , universal tester).
After you check for leaks the boost control settings are where you need to go next. I see a lot of areas of concern in the way you have it set.
In a few words, your **** is jacked.
You didn't specify what units you are set to. If you are in PSI, your start boost is set to 15psi. If you are in kPa, your start boost is set to 21psi. It's a big difference.
What's most likely happening is that your wastegate is completely shut until the start boost pressure is reached, then the commanded duty cycle (SET%) is too low, and your gain is trying to overcompensate because it's maxed. You are passing through the Start boost setpoint and there's some kind of hysteresis or other thing going on. Then you have to shift before it can build up boost again through closed loop feedback.
If you don't know what I'm talking about you need to read this thread:
https://www.rx7club.com/3rd-generati...-chart-952767/
then set every boost controller setting to the minimum and start tuning it all over again. This image is in the thread:
After you check for leaks the boost control settings are where you need to go next. I see a lot of areas of concern in the way you have it set.
In a few words, your **** is jacked.
You didn't specify what units you are set to. If you are in PSI, your start boost is set to 15psi. If you are in kPa, your start boost is set to 21psi. It's a big difference.
What's most likely happening is that your wastegate is completely shut until the start boost pressure is reached, then the commanded duty cycle (SET%) is too low, and your gain is trying to overcompensate because it's maxed. You are passing through the Start boost setpoint and there's some kind of hysteresis or other thing going on. Then you have to shift before it can build up boost again through closed loop feedback.
If you don't know what I'm talking about you need to read this thread:
https://www.rx7club.com/3rd-generati...-chart-952767/
then set every boost controller setting to the minimum and start tuning it all over again. This image is in the thread:
These settings are straight from the tuner/builder. The only thing I altered slightly was the GAIN, in an effort to get it to hold. Originally the GAIN was set to 30 and I cranked it to 35.
If I'm understanding the information in your thread and what you're saying here, perhaps I need to have slightly higher SET values but less GAIN?
I will follow your advice and start from scratch. I'll drop SET to 0, GAIN to zero and SET GAIN to 0.
Starting with adjusting SET and SET GAIN incrementally until near desired boost levels. Then, dial in some GAIN until I have stability and boost pressure as desired.
Thank you for the advice dude!
Nick
02-29-16, 12:59 PM
#13
Thank you for the feedback!
These settings are straight from the tuner/builder. The only thing I altered slightly was the GAIN, in an effort to get it to hold. Originally the GAIN was set to 30 and I cranked it to 35.
If I'm understanding the information in your thread and what you're saying here, perhaps I need to have slightly higher SET values but less GAIN?
These settings are straight from the tuner/builder. The only thing I altered slightly was the GAIN, in an effort to get it to hold. Originally the GAIN was set to 30 and I cranked it to 35.
If I'm understanding the information in your thread and what you're saying here, perhaps I need to have slightly higher SET values but less GAIN?
I will follow your advice and start from scratch. I'll drop SET to 0, GAIN to zero and SET GAIN to 0.
Starting with adjusting SET and SET GAIN incrementally until near desired boost levels. Then, dial in some GAIN until I have stability and boost pressure as desired.
Starting with adjusting SET and SET GAIN incrementally until near desired boost levels. Then, dial in some GAIN until I have stability and boost pressure as desired.
Carry a paper logbook with you (or make an Excel file on a mobile device or laptop). Each time you make a change, record your settings used, your peak boost and boost at redline (it naturally tapers down a bit usually) and observe any instability. This is easier if you have an assistant, or if you have the ability to datalog the ECU.
Make it easier for yourself by using peak hold function to record max boost. I don't remember off the top of my head if the Spec II has that ability or not. A power FC commander can display peak values by pressing the up button in monitor mode, and peak values can be cleared by pressing left or right button.
Try to be as scientific about it as you can and look for trends in the data. That's what tuning is all about.
02-29-16, 08:44 PM
#15
Hey guys,
Thanks for all the input, I've tweaked things and here's where we stand:
SET: 33
GAIN: 16
SET GAIN: 130
I began at 0,5,0 (SET,GAIN,SET GAIN). I then increased the SET value in increments of 5 and the SET GAIN value by 25. I started basically at 5/25 then 10/50, 15/75, 20/100, 25/125.
When I got to 25/125, I was seeing about 13 pounds of boost initially then trailing off to around 8 pounds. So, I began dialing in GAIN. I started off increasing gain in increments of 3 until I began to see the boost stay closer to 10, while peaking at around 14 pounds.
Now it gets interesting. I now was at 30 SET, 10 GAIN and 150 SET GAIN. With these settings I saw initial boost of around 14-15 pounds, then a drop to ten for a few moments then a rally or "surge" back up to 13-14 pounds.
Unfortunately I was driving home in traffic and couldn't really get it to redline to see if it held all the way.
I began to think that perhaps I needed to introduce more GAIN but lower the SET GAIN some. It's like the system comes in strong due to the SET GAIN setting, but then loses it and surges back up.
This, I lowered the SET GAIN from 150 to 130 and increased my GAIN and SET values to push the boost a bit further.
I haven't been able to test it but it seems to be less now even with the higher values in SET and GAIN. I last saw about 14 pounds initially and like 9 pounds afterwards.
I am not sure if I'm on the right track here. I am very curious about the surge in boost though...
Your thoughts?
Nick
Thanks for all the input, I've tweaked things and here's where we stand:
SET: 33
GAIN: 16
SET GAIN: 130
I began at 0,5,0 (SET,GAIN,SET GAIN). I then increased the SET value in increments of 5 and the SET GAIN value by 25. I started basically at 5/25 then 10/50, 15/75, 20/100, 25/125.
When I got to 25/125, I was seeing about 13 pounds of boost initially then trailing off to around 8 pounds. So, I began dialing in GAIN. I started off increasing gain in increments of 3 until I began to see the boost stay closer to 10, while peaking at around 14 pounds.
Now it gets interesting. I now was at 30 SET, 10 GAIN and 150 SET GAIN. With these settings I saw initial boost of around 14-15 pounds, then a drop to ten for a few moments then a rally or "surge" back up to 13-14 pounds.
Unfortunately I was driving home in traffic and couldn't really get it to redline to see if it held all the way.
I began to think that perhaps I needed to introduce more GAIN but lower the SET GAIN some. It's like the system comes in strong due to the SET GAIN setting, but then loses it and surges back up.
This, I lowered the SET GAIN from 150 to 130 and increased my GAIN and SET values to push the boost a bit further.
I haven't been able to test it but it seems to be less now even with the higher values in SET and GAIN. I last saw about 14 pounds initially and like 9 pounds afterwards.
I am not sure if I'm on the right track here. I am very curious about the surge in boost though...
Your thoughts?
Nick
02-29-16, 09:51 PM
#16
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Here's how I tuned mine. Copied from Evo forums.
How To Tune Your Greddy Profec B spec II
updated 9/1/4
Before you begin, you should have an idea of what you're aiming for. For EVOs, 19psi (131 kPa) seems to be a safe setting based on what people on the forums have found since it is close to what the stock boost pressure is, yet there is an increase in power due to the Greddy unit keeping the boost close to 19psi while the stock boost tapers off as the RPMs increase. I will henceforth refer to what you're aiming for as "desired boost pressure".
Definitions and things you need to know before you start:
SET This is how you set the boost pressure. Rather than setting it in psi or kPa, the Greddy unit allows you to adjust it as a percentage value, from 0% (greddy unit essentially turned off) to 100% (greddy unit will set the boost as high as it can). This setup demands a certain amount of trial-and-error to properly configure it since you have to make adjustments, then drive under WOT (Wide Open Throttle) and see what the maximum boost pressure achieved was throughout the entire RPM range. SET SHOULD BE SET TO A CONSERVATIVE VALUE WHEN BEGINNING TO TUNE YOUR GREDDY UNIT. 30% SEEMS TO BE A CONSERVATIVE SETTING BASED ON MY TESTING AND BASED ON OTHER REPORTED NUMBERS FROM EVO OWNERS AND TAKING INTO CONSIDERATION THE LINK BETWEEN SET AND GAIN (see GAIN below).
GAIN is defined in the manual as the value to adjust the "boost consistency". You don't really need to know exactly what that means. You should set GAIN to 0 when beginning, and you will then test the car under WOT while paying attention to the boost pressure. If the boost goes up and then falls off at higher RPM, you will want to increase the GAIN by a conservative amount (5% should be relatively conservative to begin with, then when you want to fine-tune it, you can go down to intervals of 1%). When you increase the GAIN value, the corresponding boost that you will go up to will be higher even if you leave the SET value alone. GAIN SHOULD BE SET TO 0 WHEN BEGINNING TO TUNE YOUR GREDDY UNIT.
START BOOST (also known as SET GAIN because that is what is displayed on the unit when adjusting this setting) is the lowest boost that the Greddy unit will begin increasing the boost from under WOT. You want this to be as close to the SET value as possible, since you want to keep as close to your desired boost as possible. However, setting it too close to the SET value will cause the boost to spike. You should set this to a conservative setting when beginning to tune your Greddy unit. Then you can fine-tune it later to get it as close to the SET value as possible without causing the boost to spike. Fortunately, you can set this in psi or kPa, thankfully Greddy didn't decide to let this be adjustable in % like the SET value. START BOOST SHOULD BE SET TO YOUR DESIRED BOOST PRESSURE MINUS 4 PSI (about 28 kPa).
WARNING is the maximum boost that you do not want to exceed. Fortunately, you can also set this in psi or kPa like the START BOOST value. When the boost exceeds the WARNING level, it will kick in the LIMITER, which decreases the boost a certain amount that you can set. WARNING SHOULD BE SET TO YOUR DESIRED BOOST PRESSURE PLUS 1 PSI (about 7 kPa).
LIMITER is the boost percentage that the Greddy unit will lower by when the WARNING boost pressure is hit. LIMITER SHOULD BE SET TO 4%.
PEAK is the peak boost value that the unit has seen since the last time it was cleared. To clear it, go to the peak boost display, and hold down the set **** until the unit beeps and "---" is displayed. IT IS A GOOD IDEA TO CLEAR THIS BEFORE YOU BEGIN JUST IN CASE YOUR UNIT HAS A HIGH BOOST ALREADY RECORDED.
LAST BOOST shows you the last boost that was recorded every time the accelerator is released for 3 seconds. TURN LAST BOOST ON BECAUSE IT IS A GOOD DIAGNOSTIC TOOL WHEN TUNING YOUR UNIT.
Keep in mind that when displaying in kPa, it does not show it technically in kPa, but rather misleadingly in bars, which Greddy inconveniently tries to justify by sticking x100 kPa next to the display. Therefore, 100 kPa will be displayed as 1.00 x100 kPa. Psi will also unfortunately be displayed in psi x10 so that 19 psi will show as 190, adding to the confusion.
Another very important thing to keep in mind is that when you first power on your car or the Greddy unit, WARNING will be set to 14.5 psi (100kPa, or 1 bar) until you interact with the Greddy unit by pressing any button. This "feature" is not documented in the manual.
Also keep in mind that atmospheric conditions affect the operation of your boost controller. When it is hot, you will get different results than when it is cold. One possible way of solving this issue is tuning your Greddy unit under the "Lo" mode for when it is relatively cold, and under the "High" mode for when it is relatively hot. Unfortunately, two modes are hardly enough for somebody that needs to account for very different summer and winter climates, and also for more aggressive settings for when increased performance is desired.
The maximum boost that you will see is also not consistent throughout the gears, which adds even more to the confusion. Unfortunately, if you've already increased your start boost to the maximum setting that doesn't give you surging, then there seems to be no way to get around this variance in boost pressure from low to high gears. I don't know if this is a limitation of the greddy unit specifically, or if it's something inherent to electronic boost controllers in general. The only two things that you can do to compensate is the following:
1. Set it to the "safest" of the settings that does not trip your limiter. To do this, tune the unit to your desired boost pressure in fifth gear.
2. Tune the "Lo" and "Hi" settings corresponding to having the boost maximized during the low gears and during the high gears. This would require you to manually hit the button to switch to the "Hi" setting when you shift to third gear or whatever you started tuning your "Hi" setting at. This is why Greddy makes the wireless remote switch that straps to your steering wheel to switch between "Hi" and "Lo" settings.
The following steps should be taken in exactly this order, taking into consideration all of the previous information:
1. Change boost pressure units to psi if so desired (see manual).
2. Set WARNING to your desired boost pressure plus 1 psi (about 7 kPa) (see above).
3. Set START BOOST (SET GAIN) to your desired boost pressure minus 4 psi (about 28 kPa)(see above).
4. Clear PEAK boost value (see above).
5. Set LAST BOOST to ON (see above).
6. Set GAIN to 0 (see above).
7. Set SET to 30% (see above).
8. Set LIMITER to SET minus 4% (26% if you followed #7).
9. Test for boost falloff at high rpm. You should probably do this in a wide open area with no other cars nearby and preferably no cops. It is also good to have somebody in the car with you that can watch the gauge while you concentrate on not wrecking your car. If there is no boost falloff, then go to #10. If there is boost falloff, then increase the GAIN by 5% and test again. Keep in mind that when you increase the GAIN value, the corresponding boost that you will go up to will be higher even if you leave the SET value alone. Repeat until the boost pressure does not decrease, or until you feel surging. If you feel surging and the boost pressure still decreases (not sure if this is possible) then decrease to the last level that you did not feel surging at.
10. Increase SET by 2% and adjust LIMITER accordingly, then test again. Keep increasing by 2% until desired boost level is obtained.
11. Increase START BOOST (SET GAIN) by 1 increment and test until surging is felt or the WARNING level is hit and the display turns red, then decrease to the previous setting.
Once you have followed these steps, you will have roughly tuned your unit. To fine-tune it, repeat steps 9 and 10 except this time only increase or decrease by 1 increment.
Hope this helps somebody. Please let me know if something is wrong, or I missed something.
updated 9/1/4
Before you begin, you should have an idea of what you're aiming for. For EVOs, 19psi (131 kPa) seems to be a safe setting based on what people on the forums have found since it is close to what the stock boost pressure is, yet there is an increase in power due to the Greddy unit keeping the boost close to 19psi while the stock boost tapers off as the RPMs increase. I will henceforth refer to what you're aiming for as "desired boost pressure".
Definitions and things you need to know before you start:
SET This is how you set the boost pressure. Rather than setting it in psi or kPa, the Greddy unit allows you to adjust it as a percentage value, from 0% (greddy unit essentially turned off) to 100% (greddy unit will set the boost as high as it can). This setup demands a certain amount of trial-and-error to properly configure it since you have to make adjustments, then drive under WOT (Wide Open Throttle) and see what the maximum boost pressure achieved was throughout the entire RPM range. SET SHOULD BE SET TO A CONSERVATIVE VALUE WHEN BEGINNING TO TUNE YOUR GREDDY UNIT. 30% SEEMS TO BE A CONSERVATIVE SETTING BASED ON MY TESTING AND BASED ON OTHER REPORTED NUMBERS FROM EVO OWNERS AND TAKING INTO CONSIDERATION THE LINK BETWEEN SET AND GAIN (see GAIN below).
GAIN is defined in the manual as the value to adjust the "boost consistency". You don't really need to know exactly what that means. You should set GAIN to 0 when beginning, and you will then test the car under WOT while paying attention to the boost pressure. If the boost goes up and then falls off at higher RPM, you will want to increase the GAIN by a conservative amount (5% should be relatively conservative to begin with, then when you want to fine-tune it, you can go down to intervals of 1%). When you increase the GAIN value, the corresponding boost that you will go up to will be higher even if you leave the SET value alone. GAIN SHOULD BE SET TO 0 WHEN BEGINNING TO TUNE YOUR GREDDY UNIT.
START BOOST (also known as SET GAIN because that is what is displayed on the unit when adjusting this setting) is the lowest boost that the Greddy unit will begin increasing the boost from under WOT. You want this to be as close to the SET value as possible, since you want to keep as close to your desired boost as possible. However, setting it too close to the SET value will cause the boost to spike. You should set this to a conservative setting when beginning to tune your Greddy unit. Then you can fine-tune it later to get it as close to the SET value as possible without causing the boost to spike. Fortunately, you can set this in psi or kPa, thankfully Greddy didn't decide to let this be adjustable in % like the SET value. START BOOST SHOULD BE SET TO YOUR DESIRED BOOST PRESSURE MINUS 4 PSI (about 28 kPa).
WARNING is the maximum boost that you do not want to exceed. Fortunately, you can also set this in psi or kPa like the START BOOST value. When the boost exceeds the WARNING level, it will kick in the LIMITER, which decreases the boost a certain amount that you can set. WARNING SHOULD BE SET TO YOUR DESIRED BOOST PRESSURE PLUS 1 PSI (about 7 kPa).
LIMITER is the boost percentage that the Greddy unit will lower by when the WARNING boost pressure is hit. LIMITER SHOULD BE SET TO 4%.
PEAK is the peak boost value that the unit has seen since the last time it was cleared. To clear it, go to the peak boost display, and hold down the set **** until the unit beeps and "---" is displayed. IT IS A GOOD IDEA TO CLEAR THIS BEFORE YOU BEGIN JUST IN CASE YOUR UNIT HAS A HIGH BOOST ALREADY RECORDED.
LAST BOOST shows you the last boost that was recorded every time the accelerator is released for 3 seconds. TURN LAST BOOST ON BECAUSE IT IS A GOOD DIAGNOSTIC TOOL WHEN TUNING YOUR UNIT.
Keep in mind that when displaying in kPa, it does not show it technically in kPa, but rather misleadingly in bars, which Greddy inconveniently tries to justify by sticking x100 kPa next to the display. Therefore, 100 kPa will be displayed as 1.00 x100 kPa. Psi will also unfortunately be displayed in psi x10 so that 19 psi will show as 190, adding to the confusion.
Another very important thing to keep in mind is that when you first power on your car or the Greddy unit, WARNING will be set to 14.5 psi (100kPa, or 1 bar) until you interact with the Greddy unit by pressing any button. This "feature" is not documented in the manual.
Also keep in mind that atmospheric conditions affect the operation of your boost controller. When it is hot, you will get different results than when it is cold. One possible way of solving this issue is tuning your Greddy unit under the "Lo" mode for when it is relatively cold, and under the "High" mode for when it is relatively hot. Unfortunately, two modes are hardly enough for somebody that needs to account for very different summer and winter climates, and also for more aggressive settings for when increased performance is desired.
The maximum boost that you will see is also not consistent throughout the gears, which adds even more to the confusion. Unfortunately, if you've already increased your start boost to the maximum setting that doesn't give you surging, then there seems to be no way to get around this variance in boost pressure from low to high gears. I don't know if this is a limitation of the greddy unit specifically, or if it's something inherent to electronic boost controllers in general. The only two things that you can do to compensate is the following:
1. Set it to the "safest" of the settings that does not trip your limiter. To do this, tune the unit to your desired boost pressure in fifth gear.
2. Tune the "Lo" and "Hi" settings corresponding to having the boost maximized during the low gears and during the high gears. This would require you to manually hit the button to switch to the "Hi" setting when you shift to third gear or whatever you started tuning your "Hi" setting at. This is why Greddy makes the wireless remote switch that straps to your steering wheel to switch between "Hi" and "Lo" settings.
The following steps should be taken in exactly this order, taking into consideration all of the previous information:
1. Change boost pressure units to psi if so desired (see manual).
2. Set WARNING to your desired boost pressure plus 1 psi (about 7 kPa) (see above).
3. Set START BOOST (SET GAIN) to your desired boost pressure minus 4 psi (about 28 kPa)(see above).
4. Clear PEAK boost value (see above).
5. Set LAST BOOST to ON (see above).
6. Set GAIN to 0 (see above).
7. Set SET to 30% (see above).
8. Set LIMITER to SET minus 4% (26% if you followed #7).
9. Test for boost falloff at high rpm. You should probably do this in a wide open area with no other cars nearby and preferably no cops. It is also good to have somebody in the car with you that can watch the gauge while you concentrate on not wrecking your car. If there is no boost falloff, then go to #10. If there is boost falloff, then increase the GAIN by 5% and test again. Keep in mind that when you increase the GAIN value, the corresponding boost that you will go up to will be higher even if you leave the SET value alone. Repeat until the boost pressure does not decrease, or until you feel surging. If you feel surging and the boost pressure still decreases (not sure if this is possible) then decrease to the last level that you did not feel surging at.
10. Increase SET by 2% and adjust LIMITER accordingly, then test again. Keep increasing by 2% until desired boost level is obtained.
11. Increase START BOOST (SET GAIN) by 1 increment and test until surging is felt or the WARNING level is hit and the display turns red, then decrease to the previous setting.
Once you have followed these steps, you will have roughly tuned your unit. To fine-tune it, repeat steps 9 and 10 except this time only increase or decrease by 1 increment.
Hope this helps somebody. Please let me know if something is wrong, or I missed something.
03-01-16, 02:54 PM
#17
Hey guys,
Thanks for all the input, I've tweaked things and here's where we stand:
SET: 33
GAIN: 16
SET GAIN: 130
I began at 0,5,0 (SET,GAIN,SET GAIN). I then increased the SET value in increments of 5 and the SET GAIN value by 25. I started basically at 5/25 then 10/50, 15/75, 20/100, 25/125.
When I got to 25/125, I was seeing about 13 pounds of boost initially then trailing off to around 8 pounds.
Thanks for all the input, I've tweaked things and here's where we stand:
SET: 33
GAIN: 16
SET GAIN: 130
I began at 0,5,0 (SET,GAIN,SET GAIN). I then increased the SET value in increments of 5 and the SET GAIN value by 25. I started basically at 5/25 then 10/50, 15/75, 20/100, 25/125.
When I got to 25/125, I was seeing about 13 pounds of boost initially then trailing off to around 8 pounds.
So, I began dialing in GAIN. I started off increasing gain in increments of 3 until I began to see the boost stay closer to 10, while peaking at around 14 pounds.
Now it gets interesting. I now was at 30 SET, 10 GAIN and 150 SET GAIN. With these settings I saw initial boost of around 14-15 pounds, then a drop to ten for a few moments then a rally or "surge" back up to 13-14 pounds.
Drop gain back down to 0 or near 0 and raise SET in 10% increments if you have to in order to get the boost to not drop so hard. Don't let GAIN do much work if you can avoid it.
I don't fully agree with that method, because the guy who wrote it has a fundamental misunderstanding of what SET means and what duty cycle really does. But if it worked for you, hey a broken clock is right twice a day.
START BOOST (also known as SET GAIN because that is what is displayed on the unit when adjusting this setting) is the lowest boost that the Greddy unit will begin increasing the boost from under WOT. You want this to be as close to the SET value as possible, since you want to keep as close to your desired boost as possible.
Last edited by arghx; 03-01-16 at 02:58 PM.
03-01-16, 03:07 PM
#18
SET is probably too low. Your duty cycle is going from nearly 100% down to 25 after you get over 13psi. That's what those settings mean. It's a drastic drop. SET GAIN is doing all the work, and then it's falling on its face.
Use feed forward value first, so try adjusting SET first in this situation....
The closer you get to your intended value with feed forward control (SET and START BOOST), the less work the feedback (GAIN) has to do. If feedback has to do too much, you get winding up and surging.
Drop gain back down to 0 or near 0 and raise SET in 10% increments if you have to in order to get the boost to not drop so hard. Don't let GAIN do much work if you can avoid it.
Use feed forward value first, so try adjusting SET first in this situation....
The closer you get to your intended value with feed forward control (SET and START BOOST), the less work the feedback (GAIN) has to do. If feedback has to do too much, you get winding up and surging.
Drop gain back down to 0 or near 0 and raise SET in 10% increments if you have to in order to get the boost to not drop so hard. Don't let GAIN do much work if you can avoid it.
So, if I'm understanding you correctly, I need to get more aggressive with the SET value and back off the GAIN values. However, the SET GAIN is actually at a decent level and perhaps could even be raised, if I can see more stability in the boost after corrections. Am I right?
Basically what you're saying here is that my SET GAIN value is what's allowing the boost to come in so strong. But, as soon as it does it's job and brings my boost in at say 13 PSI, in this scenario -- my SET value being only 33, then doesn't have enough gusto to maintain that initial boost which SET GAIN was responsible for.
That makes a ton of sense, if that's indeed what's going on.
I will increase my SET values, reduce the GAIN and leave the SET GAIN where it is for the time being and report back.
Thanks!
Nick
03-02-16, 04:48 PM
#20
OK, sounds good, I'll give that a try.
I'm doing a little custom work installing my front door speakers and wiring at the moment, so I'm not driving the car for a few days. Perhaps over the weekend I'll have the chance to do some further testing.
Nick
I'm doing a little custom work installing my front door speakers and wiring at the moment, so I'm not driving the car for a few days. Perhaps over the weekend I'll have the chance to do some further testing.
Nick
03-18-16, 10:43 PM
#22
OK guys. Haven't really driven the car much cause I'm doing some interior projects so the car's kind of in pieces but I did take her out tonight.
arghx, I think your theory was spot on. I have made some adjustments and I'm now seeing peak boost of roughly 14.5-15.0 pounds initially. Then, the boost tails off just a bit to 12-13 pounds through to redline. I have a tuning issue, so I'm not going to go any higher for the moment. But, the sensation has totally changed.
Before, the drop off was so obvious and it really felt like the car was being shackled. It was being held back by the settings in the boost controller
My current settings:
SET: 55
GAIN: 15
SET GAIN: 130
Compare that to my original settings and it's clear to see why I had the issues. Again, thank you for your input guys and especially you arghx, thanks.
I will tweak further once I get this detonation/knock issue sorted. The same guy who couldn't tune my boost controller also apparently can't tune my air fuel ratio or timing.
I'll update whenever I get that worked out with final settings that produce 15 pounds from initial boost to redline. That's the goal.
Nick
arghx, I think your theory was spot on. I have made some adjustments and I'm now seeing peak boost of roughly 14.5-15.0 pounds initially. Then, the boost tails off just a bit to 12-13 pounds through to redline. I have a tuning issue, so I'm not going to go any higher for the moment. But, the sensation has totally changed.
Before, the drop off was so obvious and it really felt like the car was being shackled. It was being held back by the settings in the boost controller
My current settings:
SET: 55
GAIN: 15
SET GAIN: 130
Compare that to my original settings and it's clear to see why I had the issues. Again, thank you for your input guys and especially you arghx, thanks.
I will tweak further once I get this detonation/knock issue sorted. The same guy who couldn't tune my boost controller also apparently can't tune my air fuel ratio or timing.
I'll update whenever I get that worked out with final settings that produce 15 pounds from initial boost to redline. That's the goal.
Nick
