GM Boost control solenoid
Yeah.. I think I'm on the right track because I am really not digging the "Range" of boost available with the bleed system.. a restrictor system can go from wastegate pressure (completely off) to dangerously high (completely on) obviously not something you would want if you have the stock ECU where the solenoid would be either on or off.. but you can then in turn plumb a MBC into the mix and keep the max from going any higher than what you set..
Well, I'm not sure if it will work, but its been done on other cars and its the only thing I can think of that can retain boost control on the UTEC in some way.. Throw in the closed loop control by adding the MAP sensor, and you should have the type of control that a boost controller like the HKS EVC offers.. only you have a 2d map to work with and its built into the UTEC..
Well, I'm not sure if it will work, but its been done on other cars and its the only thing I can think of that can retain boost control on the UTEC in some way.. Throw in the closed loop control by adding the MAP sensor, and you should have the type of control that a boost controller like the HKS EVC offers.. only you have a 2d map to work with and its built into the UTEC..
Originally Posted by TearItUpSports
The duty cycle is always on time vs total time, that is just the standard. Therfore on a normally closed solenoid, 100% duty cycle would fully open the solenoid.
You may want to use the normally open option on the solenoid though, so that and increase in duty cycle directly relates to an increase in boost pressure. Is also is a good safety in case a wire came loose, that you would not be hitting 25+ psi.
The above is how the AEM EMS would handle this.
Also the above is only assuming the line runs from the turbo, to the boost solenoid, then to the wastegate in series. If they are plumbed in a T instead, the result would be opposite, where 100% duty would be minimum boost for a Normally open solenoid.
You may want to use the normally open option on the solenoid though, so that and increase in duty cycle directly relates to an increase in boost pressure. Is also is a good safety in case a wire came loose, that you would not be hitting 25+ psi.
The above is how the AEM EMS would handle this.
Also the above is only assuming the line runs from the turbo, to the boost solenoid, then to the wastegate in series. If they are plumbed in a T instead, the result would be opposite, where 100% duty would be minimum boost for a Normally open solenoid.
If connected like a typical MBC, you have a line from a vacuum source, to the solenoid, to the wastegate actuator..
0% duty cycle in a normally closed solenoid should be wastegate pressure since there's no additional pressure acting on the spring side of the actuator
100% duty cycle in a normally closed solenoid would result in a 100% open valve, therefore boost pressure would act on the wastegate actuator and hold it closed (relatively) indefinitely...
This is my understanding, please correct me if I'm WAY off, because this is confusing..
The stock bleed system operates by relieving pressure, therefore its normally open, but essentially its a normally open solenoid, therefore giving you a lower boost level, then as duty cycle increases it stays closed longer, therefore allowing less bleed, and raising pressure.. HOWEVER the primary restrictor (on the vacuum source) acts to set the maximum pressure available, and the secondary restrictor (at the solenoid) acts as a regulator for the lowest pressure... In other words, when the solenoid is closed, the primary restrictor sets the high boost point (19.5 psi), and when its open (bleeding) it sets the low boost point (16.5 psi)
In theory, if you remove both restrictors, you will allow the stock solenoid to do 100% of the regulation.. Now this might be an option however by removing the restrictors on both sides, you create what is essentially a HUGE vacuum leak, and therefore is undesirable... This could effect your engine idle, until the duty cycle goes up.. additionally whatever vacuum source you tap from, would likely have a problem functioning correctly since it would no longer get its normal signal..
In a restrictor setup, the bleed is just a residual weep hole to prevent pressure from getting trapped in the circuit.. (the advantage of using a 3 port solenoid is obvious here since the common port would go to the actuator!!) however when its providing a signal, its a "Closed loop" and therefore not bleeding as much pressure off, therefore not affecting the vacuum circuit your tapped into...
Make sense? Does this make a sound theory? (or is it actually true??)
This is actually the reason why you can't just reroute the hoses onto the stock solenoid, because its not designed to work normally closed... (I'll test this when I take it off to be certain that its open when not energized low boost) It actually makes sense since should the car experience a electrical problem, or the wiring harness to the solenoid became damaged, you'd likely want it to default to a low boost setting and not high..
MalibuJack
Here is my take on how the stock system works. There is a vacum line that runs from the pressure source to the wastgate actuator with a tee in the line that goes to the stock solenoid. The function of this system is to regulate the pressure by opening or closing the wastegate. I know that this is probably basic information, but I wanted to cover it first. As psi increases, the wastgate stays closed. When the psi reaches the wastegate springs threshold limit, the wastgate opens and relieves pressure on the exhaust side to alow the psi to remain the constant pressure of the wastgate spring threshold limit. In most evo's this is 19 ~ 19.5 psi.
Now for the fun part of the equation. I believe that the stock inline solenoid stays in a fail closed position. This means that there is no voltage and the solenoid stays closed. At some point, which is determined by the ECU, the solenoid opens to relieve pressure in the vacuum line that is connected from the pressure source to the wastgate actuator. This allows the "electronic" solenoid to start regulating pressure and not the wastegate spring. I belive this was put in place to relieve the stress on the engine and not have 19 ~ 19.5 psi of constant pressure. The solenoid bleeds the pressure down to 16 ~ 16.5 psi. The reason why I say this, is that my defi boost gauge, which is electric, peaks up to 1.4 bar, and then back down to 1.1 to 1.2. When it is down to 1.1 and 1.2, it moves between the two readings very very fast. It kind of reminds me of when my eyelid starts to jitter after reading post after post.
My reasoning behind all of this is two part.
1. Most turbo systems are regulated by a vacuum line from the turbo to the wastegate. For more "stock" boost pressure, you simple change the spring to a higher spring rate in the waste gate. This only applies to an external style wastegate, as the internal one is usually a sealed unit. It is true that you can lengthen or shorted the rod coming out of it to regulate a constant boost pressure, but that is another topic for another time.
2. For a boost controller install on the Evo, electronic or manual, you disconnect the solenoid from the vacuum line from the pressure source to the wastgate actuator. You then remove this vacuum line and install a new one with the new solenoid, either electronic or manual, in series with the pressure source, and the wastegate actuator. This in turn becomes what the stock solenoid was doing, but kinda of different. The new solenoid has a fail open position, to rely on the wastegates actuator spring.
The simplest way to test this is to remove the hose on the tee and just plug it with a vacuum cap, and tie wrap. This hose is the one that leads to the stock solenoid. I hope this helps, and right!!!
Here is my take on how the stock system works. There is a vacum line that runs from the pressure source to the wastgate actuator with a tee in the line that goes to the stock solenoid. The function of this system is to regulate the pressure by opening or closing the wastegate. I know that this is probably basic information, but I wanted to cover it first. As psi increases, the wastgate stays closed. When the psi reaches the wastegate springs threshold limit, the wastgate opens and relieves pressure on the exhaust side to alow the psi to remain the constant pressure of the wastgate spring threshold limit. In most evo's this is 19 ~ 19.5 psi.
Now for the fun part of the equation. I believe that the stock inline solenoid stays in a fail closed position. This means that there is no voltage and the solenoid stays closed. At some point, which is determined by the ECU, the solenoid opens to relieve pressure in the vacuum line that is connected from the pressure source to the wastgate actuator. This allows the "electronic" solenoid to start regulating pressure and not the wastegate spring. I belive this was put in place to relieve the stress on the engine and not have 19 ~ 19.5 psi of constant pressure. The solenoid bleeds the pressure down to 16 ~ 16.5 psi. The reason why I say this, is that my defi boost gauge, which is electric, peaks up to 1.4 bar, and then back down to 1.1 to 1.2. When it is down to 1.1 and 1.2, it moves between the two readings very very fast. It kind of reminds me of when my eyelid starts to jitter after reading post after post.
My reasoning behind all of this is two part.
1. Most turbo systems are regulated by a vacuum line from the turbo to the wastegate. For more "stock" boost pressure, you simple change the spring to a higher spring rate in the waste gate. This only applies to an external style wastegate, as the internal one is usually a sealed unit. It is true that you can lengthen or shorted the rod coming out of it to regulate a constant boost pressure, but that is another topic for another time.
2. For a boost controller install on the Evo, electronic or manual, you disconnect the solenoid from the vacuum line from the pressure source to the wastgate actuator. You then remove this vacuum line and install a new one with the new solenoid, either electronic or manual, in series with the pressure source, and the wastegate actuator. This in turn becomes what the stock solenoid was doing, but kinda of different. The new solenoid has a fail open position, to rely on the wastegates actuator spring.
The simplest way to test this is to remove the hose on the tee and just plug it with a vacuum cap, and tie wrap. This hose is the one that leads to the stock solenoid. I hope this helps, and right!!!
Last edited by sgplancer; Jul 29, 2004 at 08:18 AM.
Ok.. that makes more sense.. In any case regulating the pressure to it causes it to open later.. I knew I was getting myself confused.. If the solenoid needs to be normally OPEN, then it will open at wastegate pressure.. Makes sense.. the less you pass through, the higher the pressure needed to pass through "10 psi" to the actuator..
Damn I was totally foncused.. but at least my theory is sound.. just need to make sure I use the normally open, not normally closed side.. I have to review my MBC Docs since it likely says to open the valve all the way then close it until you raise boost.. so I'm an idiot and missed an obvious point..
but this should still work..
Damn I was totally foncused.. but at least my theory is sound.. just need to make sure I use the normally open, not normally closed side.. I have to review my MBC Docs since it likely says to open the valve all the way then close it until you raise boost.. so I'm an idiot and missed an obvious point..
but this should still work..
Well if you do get it to work, start a new post so we all can follow in the footsteps and try it for our own cars.
On a side note, I need turboxs to call me!!!!! I am still trying to get fixed up with my stage 2 kit and tuner package. All of this reading of the posts needs to be put to good use.
Sorry for the rant!!!
On a side note, I need turboxs to call me!!!!! I am still trying to get fixed up with my stage 2 kit and tuner package. All of this reading of the posts needs to be put to good use. Sorry for the rant!!!
Well I consulted the shop manual to see how the system works.
Although the manual has conflicting info (via a typo), I believe the solenoid is a normally closed one. This will actually need to be tested to be sure.
BTW the solenoid has a resistance of 29-35 Ohms.
The wastegate actuation pressure is ~1 bar, so when the solenoid is closed, the wastegate would basically hold boost to 14.7 psi.
As the solenoid opens, there is less pressure on the wastegate actuator, thus keeping it closed longer and allowing the boost pressure to rise.
Now the Evo boost control is open loop. Basically it calculates what boost would be for a certain RPM vs throttle position (or perhaps speed vs throttle), and then begins to close the solenoid.
If you were to plumb the system the same way as stock, you would want to wire your GM solenoid as normally closed, so that as your duty cycle increases, you are raising the boost pressure. 0% duty would be minimum boost. I am not exactly sure the best way to use a MBC as a safety net in this operation or if it is possible.
I think however that you should plumb it in series, and use the GM solenoid as normall open. In this scenario you would still have 0% duty cycle equal to minimum boost. You could also use the MBC as a safety if you run it as a bypass to the solenoid (T into the lines before and after the solenoid). This would provide a path around the solenoid in case the pressure ever gets above a certain level.
So in summary I think both you guys (sgplancer and malibujack) are thinking opposite to what is going on, but if you look at how the system is plumbed it should make sense (a diagram is on the underside of the hood).
Basically closed solenoid means that turbo pressure goes straight to the wastegate actuator opening it sooner. The more the solenoid is open, the more air is bled off, leaving less to open the wastegate. The wastegate will only and always open when it sees 14.7 psi
EDIT: Hehe 3 posts appeared while i was typing this up during the last 30 minutes back and forth from the shop manual CD.
Although the manual has conflicting info (via a typo), I believe the solenoid is a normally closed one. This will actually need to be tested to be sure.
BTW the solenoid has a resistance of 29-35 Ohms.
The wastegate actuation pressure is ~1 bar, so when the solenoid is closed, the wastegate would basically hold boost to 14.7 psi.
As the solenoid opens, there is less pressure on the wastegate actuator, thus keeping it closed longer and allowing the boost pressure to rise.
Now the Evo boost control is open loop. Basically it calculates what boost would be for a certain RPM vs throttle position (or perhaps speed vs throttle), and then begins to close the solenoid.
If you were to plumb the system the same way as stock, you would want to wire your GM solenoid as normally closed, so that as your duty cycle increases, you are raising the boost pressure. 0% duty would be minimum boost. I am not exactly sure the best way to use a MBC as a safety net in this operation or if it is possible.
I think however that you should plumb it in series, and use the GM solenoid as normall open. In this scenario you would still have 0% duty cycle equal to minimum boost. You could also use the MBC as a safety if you run it as a bypass to the solenoid (T into the lines before and after the solenoid). This would provide a path around the solenoid in case the pressure ever gets above a certain level.
So in summary I think both you guys (sgplancer and malibujack) are thinking opposite to what is going on, but if you look at how the system is plumbed it should make sense (a diagram is on the underside of the hood).
Basically closed solenoid means that turbo pressure goes straight to the wastegate actuator opening it sooner. The more the solenoid is open, the more air is bled off, leaving less to open the wastegate. The wastegate will only and always open when it sees 14.7 psi
EDIT: Hehe 3 posts appeared while i was typing this up during the last 30 minutes back and forth from the shop manual CD.
Last edited by TearItUpSports; Jul 29, 2004 at 09:43 AM.
ok I drew up a diagram of the new configuration.. since an MBC is a checkvalve, it will open at whatever pressure you set effectively bypassing the solenoid in a condition where the pressure goes higher than desired (overboost)
The MBC and Solenoid are run in parallel to eachother so the path will take the one with least restriction.. then one hose goes to the intake manifold, the other goes to the wastegate actuator.. If I set the MBC correctly, It should function similar to stock and not overboost more than my setting...
Also, this is now an entirely closed circuit and no longer a controlled "Leak" and should no longer cause issues with the DV opening under boost due to a insufficient signal (within reason since the hose and its length will have some effect)
Ok.. when I get my new solenoids, I will draw up a new diagram.. FWIW this Will work as long as I use a 8ohm resistor in series (how many watts for 12 volts?) with the GM solenoid to bring it up to the resistance required for the ECU to be happy. I think..
Thanks guys.. This might actually be a good product for TXS to sell since they do manufacture and sell some damn nice boost controllers..
Whaddaya think?
closed loop Boost control upgrade kit..
1) Checkball type MBC preset to 21psi (safe starting setting)
2) GM Solenoid, resistor, and pigtail (Preassembled with the MBC T'd)
3) GM MAP sensor with wiring harness
4) sample boost map..
5) misc parts to assemble
Sounds like an idea??
Plus, its something that can be used on any evo to control boost from a flash to any type of setup that uses the stock solenoid but also provides adjustable overboost protection.. This is almost a required upgrade for an aftermarket too!!
The MBC and Solenoid are run in parallel to eachother so the path will take the one with least restriction.. then one hose goes to the intake manifold, the other goes to the wastegate actuator.. If I set the MBC correctly, It should function similar to stock and not overboost more than my setting...
Also, this is now an entirely closed circuit and no longer a controlled "Leak" and should no longer cause issues with the DV opening under boost due to a insufficient signal (within reason since the hose and its length will have some effect)
Ok.. when I get my new solenoids, I will draw up a new diagram.. FWIW this Will work as long as I use a 8ohm resistor in series (how many watts for 12 volts?) with the GM solenoid to bring it up to the resistance required for the ECU to be happy. I think..
Thanks guys.. This might actually be a good product for TXS to sell since they do manufacture and sell some damn nice boost controllers..
Whaddaya think?
closed loop Boost control upgrade kit..
1) Checkball type MBC preset to 21psi (safe starting setting)
2) GM Solenoid, resistor, and pigtail (Preassembled with the MBC T'd)
3) GM MAP sensor with wiring harness
4) sample boost map..
5) misc parts to assemble
Sounds like an idea??
Plus, its something that can be used on any evo to control boost from a flash to any type of setup that uses the stock solenoid but also provides adjustable overboost protection.. This is almost a required upgrade for an aftermarket too!!
Last edited by MalibuJack; Jul 29, 2004 at 10:24 AM.
That sounds like a good plan.
As far as matching the stock resistance, I am not sure, since I plan on using the EMS it is not something I worried about. You could also use a 36 Ohm resistor in parallel to accomplish the task as well, which would be a better solution I think.
FWIW the diverter (BOV) opens at negative 0.56 Bar.
As far as matching the stock resistance, I am not sure, since I plan on using the EMS it is not something I worried about. You could also use a 36 Ohm resistor in parallel to accomplish the task as well, which would be a better solution I think.
FWIW the diverter (BOV) opens at negative 0.56 Bar.
Good point, Though I think that would increase the load across it and raise the "power" required to drive it which might trigger a CEL, plus I suspect that would generate quite a bit of heat... I'll have to check that..
Oh, and the good thing about closed loop on the UTEC is its the "digital value" of the MAP sensor.. so the target is the same regardless of if you adjust the MBC, the MBC just sets the max overboost condition.. Assuming your MAP sensor is properly calibrated, it should always hit the pressure you set as long as its lower than the MBC's checkvalve setting (19psi or whatever) regardless of weather conditions or altitude..
in open loop boost... duty cycle would likely be somewhere around 50%.. but if you go over that, boost will never go above the set MBC point.. but in this case, the duty cycle will vary based on other conditions, and boost may vary based on conditions..
in open loop boost... duty cycle would likely be somewhere around 50%.. but if you go over that, boost will never go above the set MBC point.. but in this case, the duty cycle will vary based on other conditions, and boost may vary based on conditions..
Last edited by MalibuJack; Jul 29, 2004 at 10:37 AM.
hey jack
i dont know if this is close but its what i did, since i put in the gt35r, i also wanted to use the utec boost controller software, so reused one of the restrictor pills in the line. i was told this setup would not work, but i tried myself and managed to get it to work.. im running closed loop boost control...
i was having trouble with the turbo being a little lazy because the wastegate would start to open at about 6 psi all the way to 19 psi... so i turned the gain down to 11 percent and had to turn the numbers down to 225 to get 19psi...
but i get 19psi by 3800 now where before i got it at almost 6000 so it helped alot...and i dont hear the wastegate opn until approx 15 psi now,..
this turbo is insane...im sure it spool a little faster with a profec b spec2 but i dont want the extra hardware so im sticking to this for now..
im runing 12 to 1 afr and richening up to 11.8 at redline and running 21 deg at the top absolutely no detonation and the evo loves it...
cams are next
regards rick
i was having trouble with the turbo being a little lazy because the wastegate would start to open at about 6 psi all the way to 19 psi... so i turned the gain down to 11 percent and had to turn the numbers down to 225 to get 19psi...
but i get 19psi by 3800 now where before i got it at almost 6000 so it helped alot...and i dont hear the wastegate opn until approx 15 psi now,..
this turbo is insane...im sure it spool a little faster with a profec b spec2 but i dont want the extra hardware so im sticking to this for now..
im runing 12 to 1 afr and richening up to 11.8 at redline and running 21 deg at the top absolutely no detonation and the evo loves it...
cams are next
regards rick