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 ?
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 ?
