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Discussion Starter · #1 ·
As I mentioned earlier this week, I was able to flash my UTec with v2.5 of the firmware. It made sense therefore to disconnect my SBC i-D solenoid, reconnect the OE solenoid, and get to grips with the much touted closed-loop-boost-control mechanism implemented in this version of the UTec software.

I just wanted to get my initial impressions down. Take these with a grain of salt as I have only spent about 1 hour of tweaking and hard runs in the car.

First, let me tell you what I know. The boost map plots TPS on the x-axis, and RPMs on the Y-axis. Each cell in the map contains seemingly arbitrary numerics, or 'ECU' to indicate that the underlying computer will take control. Nathan informed me that the valid range for these values is 0 to 500. These apparently translate to manifold absolute pressure, as monitored by your calibrated MAP sensor. Since I recalibrated my MAP sensor to be zero-referenced at my altitude of 8000ft, the MAP output will closely resemble my boost gauge with some minor discrepancy due to changes in barometric pressure. I finally settled on a value of 390 for peak boost, which corresponds (on my setup) to a calibrated MAP of about 20psi (a sea-level MAP of about 16psi). Finally, there is a master gain setting ranging from 0 to 100.

I was both pleased, and disappointed by what I found during my brief experimentation, although the net feeling was one of optimism. Overall I was surprised by how well the system performs, and I look forward to spending a lot more time with tuning my boost settings. Here are my observations:

- Boost response was just as good if not better than the SBC i-D. I was able to build boost just as quickly as the SBC i-D manual mode (open loop), and better than the SBC i-D can in auto mode (closed loop). Since I have always felt this to be the strong point of the Blitz unit, I was duly impressed.

- Boost control, or the ability to prevent spiking, is slightly inferior to the SBC i-D setup. This is something I also observed with the OE solenoid when my car was in stock configuration: Boost very briefly spikes past the target by 0.5psi or so before settling down. I would have to guess that the OE solenoid is the culprit here, and not the UTec software. I left the master gain setting at 50. Adjusting it by up to 10 points in either direction appeared to have zero perceptible effect upon neither response nor control. The spike is small and brief, and not something that would deter me from using this setup.

- The ability to map boost to TPS should fuel the PTFB propaganda, but in reality it does allow you to tune your boost for drivability. I removed all ECU control for all load columns over 10%, and ramped the boost up gradually according to TPS. This should make throttle transitions much smoother during cruise.

- Now the important part: Is the UTec able to hold your dialed MAP to the redline? The answer is; not any better than the SBC i-D with my setup (yet). This was the part I found disappointing as it seems that in theory the software should be able to cycle the solenoid such that the wastegate closes down at high RPMs, and thus maintains full boost. In reality I found the boost dropping off by 2-3psi from the peak, just as it does with my SBC i-D set to manual mode. I actually feel like the SBC i-D does a slightly better job in auto mode, in this respect. I think this is probably more a function of the IHI wastegate and the flow characteristics of the VF22 at this altitude, than it is to do with the boost controller. I briefly considered using a higher MAP value toward redline, but if I were to pursue that route I may as well just switch to the UTec open-loop control which allows you to directly control the solenoid duty cycle.

- Finally, I think the nicest feature of MAP-based closed loop control is that in theory you should achieve the same manifold pressure regardless of changes in the ambient air density. Thus, I think you should actually see less boost on colder days as the UTec attempts to achieve the same manifold pressure. This is probably a better situation in regards to the ability to tune consistently for repeatable manifold pressures. It is a subtle difference from boost-referenced control, but important I think.


I have a lot more playing to do, and I will try to get Nathan's input on the issue around the ability of this setup to better hold boost to redline. Right now it's too early to say whether I would ultimately stay with this setup or revert to the SBC i-D.

You know, there's been a bunch of hype around closed-loop boost control with many of the people getting caught up in it not even knowing 'what is is'. At the risk of stating the obvious, I think some folk tend to overlook the following reality: And that is, you need load to build boost. The UTec closed-loop-controller will not magically allow you to make big boost in 1st gear, regardless of what settings you dial in. And likewise it is not going to enable your tiny TD04 to hold 18psi all the way to the redline. It likely behaves just like every other closed-loop controller (including the SBC i-D) in this regard.

-Pace

p.s

Question for Nathan: Is the scale (0-500) linear in regards to how it translates to MAP? i.e. Is the difference in MAP achieved between say a value of 100 and 200, the same as the difference in MAP between 400 and 500 ?
 

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Great reporting and a great read. Thank you!
 

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Waiting for the results.
God will have my UTEC 15 december =)
Too happy not to wait very long.
Does the UTEC that God is receiving,,comes with all the NEW features??
Thanks
Tuca


:D
 

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Discussion Starter · #4 ·
Even if it does not come with the new firmware version, it will be available to download from TXS in the near future. It is a very simple process to flash your UTec with a new software version.

-Pace
 

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pace said:


- Boost response was just as good if not better than the SBC i-D. I was able to build boost just as quickly as the SBC i-D manual mode (open loop), and better than the SBC i-D can in auto mode (closed loop). Since I have always felt this to be the strong point of the Blitz unit, I was duly impressed.
Just as I expected! The UTEC boost control is indeed VERY fast; much more so than the SBCid in auto mode, and every bit as fast as the SBC-id in open loop mode. In fact it's actually faster than our HPMBC, and you can't hardly get faster than that...


pace said:
- Boost control, or the ability to prevent spiking, is slightly inferior to the SBC i-D
setup.
Proper ABC setup has everything to do with boost spiking... How many turns open do you have it? The ABC must be used in place of the stock restrictor in the FBC line to keep the spikes at bay. With the OE restrictor in place the FBC cannot flow enough to keep up.

pace said:

- Now the important part: Is the UTec able to hold your dialed MAP to the redline? The answer is; not any better than the SBC i-D with my setup (yet). This was the part I found disappointing as it seems that in theory the software should be able to cycle the solenoid such that the wastegate closes down at high RPMs, and thus maintains full boost. In reality I found the boost dropping off by 2-3psi from the peak, just as it does with my SBC i-D set to manual mode. I actually feel like the SBC i-D does a slightly better job in auto mode, in this respect. I think this is probably more a function of the IHI wastegate and the flow characteristics of the VF22 at this altitude, than it is to do with the boost controller. I briefly considered using a higher MAP value toward redline, but if I were to pursue that route I may as well just switch to the UTec open-loop control which allows you to directly control the solenoid duty cycle.

20 bucks says you could unplug the waste gate line and not hold your desired boost pressure to redline. Your VF22 turbo is likely suffering from 1 of 2 problems. 1. It can't flow any additional air at the desired boost pressure, or 2. it's very high exhaust pressures in the exhaust housing (worse for you because of your extreme altitude) is blowing the waste gate partially open. These are turbo problems, and no matter what you do for boost control they are still going to be there. To ask a VF turbo to make those pressure ratios at that high above sea level is borderline insane. For what it's worth they have a hard time holding that pressure at SEA LEVEL. At the pressure ratio you are trying to spin it... forgetaboutit...


pace said:
- Finally, I think the nicest feature of MAP-based closed loop control is that in theory you should achieve the same manifold pressure regardless of changes in the ambient air density. Thus, I think you should actually see less boost on colder days as the UTec attempts to achieve the same manifold pressure.

Nope! The boost control seeks to achieve the same MAP level not charge density level. It's going to drive to a given pressure no matter the ambient conditions.

Other thoughts...
1. Your working the FBC very hard (high 300s) and i suspect you might need to open the ABC to help stabilize the boost curve a bit since at that level it's almost wide open.
2. You should recalibrate your map sensor to sea level, and then switch the UTEC over to "gauge mode."
3. You should rescale your load points to make up for your altitude. You'll never get 18psi MAP up there, so you might as well lower the MAX mapping point to 16psi to give you better resolution over the open loop load points.
4. Lower gain #s = faster spool, but more spikes. Higher gain #s= slower spool, but much less spikes.
5. As stated in the manual the numbers in the boost map are not MAP, KPA, PSI or any other "pressure reference." I have not found them to be 100% linear, since they are a representation of a point on the MAP sensor signal. That signal is compressed in some spots, and as such i expect the UTEC boost numbers to compress and expand as well. I'd take time to explain it further, but it's proprietary technology that I’d put against any other "closed loop" boost controller on the market and we are not quite ready to give away the actual workings of it just yet.
6. Lastly, just because it's closed loop doesn't mean it's an UBER controller. It's not going to do anything magic, nor is it going to solve a turbo related problem.
7. For reference, the UTEC should control the 3-port Subaru solenoid quite well.

-Nathan
 

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Discussion Starter · #6 ·
Re: Re: UTec Closed Loop Boost Control

nmyeti said:


Proper ABC setup has everything to do with boost spiking... How many turns open do you have it? The ABC must be used in place of the stock restrictor in the FBC line to keep the spikes at bay. With the OE restrictor in place the FBC cannot flow enough to keep up.
Since I have neither the ABC nor the stock restrictor in place, maybe the slight spike is to be expected. However, I'm pretty satisfied with the current performance so I may leave it as is.

nmyeti said:


20 bucks says you could unplug the waste gate line and not hold your desired boost pressure to redline. Your VF22 turbo is likely suffering from 1 of 2 problems. 1. It can't flow any additional air at the desired boost pressure, or 2. it's very high exhaust pressures in the exhaust housing (worse for you because of your extreme altitude) is blowing the waste gate partially open. These are turbo problems, and no matter what you do for boost control they are still going to be there. To ask a VF turbo to make those pressure ratios at that high above sea level is borderline insane. For what it's worth they have a hard time holding that pressure at SEA LEVEL. At the pressure ratio you are trying to spin it... forgetaboutit...

W00t! I'm insane!

I would tend to agree with you regarding your assertion that the wastegate is being blown open. Both JaMa and David have reinforced theirs with external springs, with very positive results. I mentioned the observation to see if you had any further insight into the problem and to highlight the limitations of boost controllers in overcoming the shortcomings of turbocharger sizing and wastegate design. What lead me to this was a post I saw on wrxhackers.com (I think) where a user posted that neither he nor yourself could figure out why his setup would not hold boost to the redline during a recent dyno session. It seemed too obvious so I wondered if I was missing something.

nmyeti said:


Nope! The boost control seeks to achieve the same MAP level not charge density level. It's going to drive to a given pressure no matter the ambient conditions.

Hmm...humor me a little longer on this one. Sure, the boost control seeks to achieve the same MAP regardless of conditions. But I meant that gauge boost may fluctuate. It seems to me that cooler denser charge would require less boost (pressure above the ambient) to achieve the same absolute manifold pressure, no? The fact that MAP is a function of air density explains why the same gauge boost at altitude results in a lower manifold pressure than at sea-level. Surely that is just an exaggerated example of what happens when the ambient air temperature drops; less gauge boost to achieve the same MAP. This phenomena is visible because boost gauges are relative referenced from the current ambient pressure, whereas the MAP sensor reads absolute pressure. Correct?

nmyeti said:


Other thoughts...
1. Your working the FBC very hard (high 300s) and i suspect you might need to open the ABC to help stabilize the boost curve a bit since at that level it's almost wide open.
2. You should recalibrate your map sensor to sea level, and then switch the UTEC over to "gauge mode."
3. You should rescale your load points to make up for your altitude. You'll never get 18psi MAP up there, so you might as well lower the MAX mapping point to 16psi to give you better resolution over the open loop load points.
4. Lower gain #s = faster spool, but more spikes. Higher gain #s= slower spool, but much less spikes.
5. As stated in the manual the numbers in the boost map are not MAP, KPA, PSI or any other "pressure reference." I have not found them to be 100% linear, since they are a representation of a point on the MAP sensor signal. That signal is compressed in some spots, and as such i expect the UTEC boost numbers to compress and expand as well. I'd take time to explain it further, but it's proprietary technology that I’d put against any other "closed loop" boost controller on the market and we are not quite ready to give away the actual workings of it just yet.
6. Lastly, just because it's closed loop doesn't mean it's an UBER controller. It's not going to do anything magic, nor is it going to solve a turbo related problem.
7. For reference, the UTEC should control the 3-port Subaru solenoid quite well.

-Nathan
1. I have the boost set at 350 now. I may connect the ABC as per your recommendation. However, I am somewhat concerned that this will significantly slow my boost response. The memory of the Unichip+ABC setup is still fresh in my mind, as it was my sole motivation for moving to the SBC i-D.

2. & 3. Let's assume that the difference in MAP readings due to my altitude is -4psi. Given that fact, what difference does it make whether I recalibrate my MAP sensor to my altitude and use a MAP scale from 0 to 18 versus leaving my MAP sensor sea-level calibrated and using a MAP scale from -4 to 14. The net result would be the same, correct? I guess one motivation for the latter is that my logged MAP readings would make more sense to you guys in the eventuality of interpreting my logs.

4. Thanks for clarifying.

5. Yup, I noted that in the PM you sent me. However, there was no indication whether there is a linear relationship to boost. The reason I wanted to know is so that I could sensibly map boost to TPS. Knowing that there is not necessarily a linear relationship will make that task somewhat more difficult. Are there any plans in future releases to apply your proprietary algorithm to the boost map values such that absolute (calibrated) MAP values could instead be specified by the user?

6. Pretty much what I said in my original post. I did not intend to insinuate that TXS overhyped this capability; just that hysteria has been generated by the craving masses. Overall I was very, very impressed with what you guys have done. Enough that I will probably leave it in place and ditch my SBC i-D. Is that a good enough plug for ya - coming from a professional software systems engineer? :) ;)

7. What is the 3-port Subaru solenoid. Please elaborate.

Thanks for the feedback. I try to report my observations in as objective and straightforward manner as possible. Sometimes something doesn't make sense when you're not in possession of the relevant facts, although you did a good job of setting me on the right path. I'm sure the updated users manual which no doubt will be released when this version goes public, would have addressed many of the questions I raised.


-Pace
 

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Re: Re: Re: UTec Closed Loop Boost Control

pace said:


Hmm...humor me a little longer on this one. Sure, the boost control seeks to achieve the same MAP regardless of conditions. But I meant that gauge boost may fluctuate.
I'll have to check with Pete on this, but i don't think it's driving to a MAP point. It's driving to a boost pressure.


pace said:
1. I have the boost set at 350 now. I may connect the ABC as per your recommendation. However, I am somewhat concerned that this will significantly slow my boost response. The memory of the Unichip+ABC setup is still fresh in my mind, as it was my sole motivation for moving to the SBC i-D.
The ABC doesn't change boost response in any way. You are reacting to a very poor boost control system on the UNICHIP which has nothing to do with the UTEC. The ABC allows the solinoide to do its job a bit better.

My question is, if you are not using either the stock restrictor or the ABC, what are you using? From the sound of it, whatever it is, is working well. I'll have to buy Pete beer for designing something robust enough that i can be used effectivly in a way that was never intended...



pace said:

7. What is the 3-port Subaru solenoid. Please elaborate.

It's a Subaru solenoid that that Link guys are fond of using on their cars. From my understanding, it is higher flowing than the stock USDM piece, and as such can be driven to higher a higher boost pressure.
 

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Discussion Starter · #8 ·
Re: Re: Re: Re: UTec Closed Loop Boost Control

nmyeti said:


I'll have to check with Pete on this, but i don't think it's driving to a MAP point. It's driving to a boost pressure.

Please get back to us on that one. It's an important distinction IMHO, as it particularly has significance for people tuning in environments of frequently changing weather or where their location results in large changes in elevation.

nmyeti said:


The ABC doesn't change boost response in any way. You are reacting to a very poor boost control system on the UNICHIP which has nothing to do with the UTEC. The ABC allows the solinoide to do its job a bit better.

My question is, if you are not using either the stock restrictor or the ABC, what are you using? From the sound of it, whatever it is, is working well. I'll have to buy Pete beer for designing something robust enough that i can be used effectivly in a way that was never intended...

I guess one of the curses of dealing with an audience that has a wide spectrum of technical prowess is that some folks will readily accept a response of 'do it because we said so!' while others want to know why. The latter are probably more of a pain in your rear end. The manual doesn't qualify why the ABC is needed, and understanding how the mechanics of the stock boost system works as well as aftermarket controllers makes it seem somewhat redundant in this application. I can't help but feel that the ABC is a bandaid to address the performance of a marginal OE solenoid. This view is reinforced somewhat by your mention of the 3 port unit.

In case you are interested, I was largely able to tune out the spiking by tweaking of the boost parameters. I don't have any restrictor in place, just the plastic 'T' that is supplied with the IHI turbos. I have an unobstructed vacuum hose going directly from the plastic 'T' to the solenoid. There is no restriction in my setup, nor any bleeding of boost signal to atmosphere other than that provided by the FBC mechanism.

Thanks for your continued feedback.

-Pace
 

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Re: Re: UTec Closed Loop Boost Control

Sorry I am kind of jumping in here a little late but I thought I would add my $0.02 worth as well ;).

nmyeti said:


20 bucks says you could unplug the waste gate line and not hold your desired boost pressure to redline. Your VF22 turbo is likely suffering from 1 of 2 problems. 1. It can't flow any additional air at the desired boost pressure, or 2. it's very high exhaust pressures in the exhaust housing (worse for you because of your extreme altitude) is blowing the waste gate partially open. These are turbo problems, and no matter what you do for boost control they are still going to be there. To ask a VF turbo to make those pressure ratios at that high above sea level is borderline insane. For what it's worth they have a hard time holding that pressure at SEA LEVEL. At the pressure ratio you are trying to spin it... forgetaboutit...


-Nathan
I installed a 11.5lb 1.5" long (thank you Home Depot $1.99) spring the other day in parrallel with the wastegate on my VF22. With boost control off my boost levels went from ~10psi up to ~14psi. NOt to shabby IMHO :). I am now able to get up to about 17-18psi in 1st, spike up to about 20psi in 2nd and it still drops down to about 17-18psi by redline. BUT then 3rd gear and up I can hold whatever boost I want to redline. Currently I am running about 19-20psi to redline (~16-17psi sea level equivalent boost).

I bought a 19lb spring but I think I will wait until spring time if I need that.

But I have a question for you Nathan. You mention that we have higher than normal pressure in the exhaust housing of the turbo? I don't really get that too much. Let me explain my whole take on that situation. First off I think I verified that the wastegate was getting blown open becuase I could set the BC to 100% dc and it would still taper the same. Mostly in 1 and 2nd gear where you are flying through the revs = LOTS of exhaust gas = has to go someplace in a hurry = push open wastegate.

Onto my take on the whole exhaust stream at altitude. Ok so lets assume relative boost pressure of 1kg/cm2 = 14.2psi. At sea level you would be flowing:

At sea level:
14.7(atmosphere) + 14.2 = 28.9psi total through the engine and exhaust housing with 14.7psi of "back pressure" on the entire exhaust system (after the housing) from atmospheric pressure.

Up here at 6000ft:
11.2(atmosphere) + 14.2 = 25.4psi total through the engine and exhaust housing. With 11.2psi of "back pressure" again from atmoshperic conditions after the exhaust housing (assuming no cats = minimal back pressure after turbo).

Enter compensation for altitude with more boost:
11.2(atmosphere) + 17.7psi = 28.9psi total through the engine and exhaust housing with ONLY 11.2psi of "back pressure" on the entire exhaust system.

Basically I was trying to setup the fact that we have more of a delta of pressure before and after the exhaust housing up here than at sea level. At sea level you are trying to flow the same total volume of gas through the engine as up here (when we boost 3.5-4psi more to compensate) BUT we have less pressure after the exhaust housing up here than you do at sea level. But it still seems like a possible wash becuase you have less restriction for the exhaust gases to flow througn the exhaust housing (not the wastegate) BUT that also means it will have less pressure trying to keep the wastegate closed as well [scratching head thinking he got no where with all this babbling] :).

Oh well to make a long story short things are better with the TXS TMIC and el cheapo' ghetto-riffic Home Depot spring in parrallel to the wastegate ;).

CHeers
 

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Re: Re: Re: UTec Closed Loop Boost Control

davidm_sh said:


Basically I was trying to setup the fact that we have more of a delta of pressure before and after the exhaust housing up here than at sea level.
To put it bluntly you are wrong. You are forgetting that the exhaust housing is before the turbine, and that the turbine spins in such a way to create backpressure. Most VF series turbo chargers create a backpressure to boost ratio of over 2:1, and in some cases (Vf22 for instance) can get as high as 3:1.

It's worse at altitude because you have to spin the turbo faster to get the same absolute boost pressure as at sea level. The faster you spin the turbine, the more restriction in the exhaust housing.

-Nathan
www.turboxs.com
 

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Re: Re: Re: Re: UTec Closed Loop Boost Control

nmyeti said:


To put it bluntly you are wrong. You are forgetting that the exhaust housing is before the turbine, and that the turbine spins in such a way to create backpressure. Most VF series turbo chargers create a backpressure to boost ratio of over 2:1, and in some cases (Vf22 for instance) can get as high as 3:1.

It's worse at altitude because you have to spin the turbo faster to get the same absolute boost pressure as at sea level. The faster you spin the turbine, the more restriction in the exhaust housing.

-Nathan
www.turboxs.com
Yup ok I can buy that :). I never really thought about the effect the turbine speed played in the whole back pressure equation.

So here is a question for you. Do you think somthing like the SR40 with a P17.5 exhuast housing would be worse up here then? I mean since we create more back pressure wouldn't we want a larger exhuast housing to help offset this? Or do we want a turbo that can flow more, like the SR40 vs VF22, at lower boost levels/lower rpms?

And to put in bluntly... thanks for clearing that up Nathan ;) [heh].
 

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nmyeti,
I have a SBC-ID installed,,and i have a UTEC coming to me:D :cool:
Now i want to know what would you really recommend for better performance?
Is it better for me to leave my SBC-ID as a boost gauge,,hook up the ABC and let the UTEC controll my boost??
Or will it have the same results if i Install the UTEC but tune it with no boost and let the SBC-ID controll my boost??
I like the idea of the UTEC controlling my boost cause the Blitz solenoid is good and i can i 1 sec change to OFF and give my car to wallet parking guys and my car with the SBC-ID in OFF mode will give only 7PSI,,as the wastegate will limit it there..
What do you think its better???What would you do?
Thanks
TUca
 

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Discussion Starter · #13 ·
Nathan is not a big fan of the SBC i-D, so I am pretty sure he would tell you to go UTec for boost control. With one of the forthcoming external map selection switches for the UTec, you could easily switch to a 'valet' low-boost map.

-Pace
 

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But i dont know if my UTEC will have that switch =(
Tuca
Hey pace,,check your PM Box..
 

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Pace an Nmiety.
I cannot sell my SBC-ID cause i have my PM-ID and i want it:D
I was thinking of leaving the SBC-ID only as a boost gauge.
But Dan from Godspeed told me that if i would not sell my SBC-ID ,it was better to let it control my boost.
He said maybe if i would sell it he would recomend then using the ABC.
Will i be able to tune my car properly using the SBC-ID auto mode ??I want to set for exemple 14PSI and it reaches 14PSI and stays there till the turbo go out of the range at 6500RPM.
How many PSI for Stg1(stock car),and how many PSI for Stg2(catless)???
Can i run the UTEC in closed loop or open loop and it will not have difference??
Thanks
Tuca
 

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There is something I dont understand here, and I think it may be how the boost control solenoid works. The stock one in open loop has a duty cycle setting, so what exactly does the percentage designate that the solenoid will do. I hear duty cycle and I start to think that the soleniod works like a fuel injector... is this true?
 

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Discussion Starter · #17 ·
SBW said:
I hear duty cycle and I start to think that the soleniod works like a fuel injector... is this true?
If you mean 'does the solenoid modulate boost like a fuel injector modulates fuel; by changing the frequency at which it opens and closes', then yes I believe your assertion is correct. Hence the term 'duty cycle'.

-Pace
 

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yeah thats what I was thinking, but i the answer Im look for here is how does it work. The Boost control solenoid specifically. boost builds and then when it builds the the preset designation, what does it do. How does it not let boost build anymore, does it open the wastegate? if so, how?

im sorry for the stupid questions, I think I might have a better understand of the closed loop versus open loop if I could understand the relationship between the solenoid, what it does, and its relationship with the wastegate.
 

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The boost controller is cycles on and off quickly so as to be open a "percentage" of the time. This bleeds off a certain amount of boost signal that would otherwise be sent to the wastegate. Since the wastegate stays closed while the FBC is cycling (for the most part) the boost is allowed to build in the intake tract.

When the FBC starts to send more signal than it bleeds to the wastegate, the WG opens and turbo boost is reduced.
 
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