Control Start Pressure and Closed Loop Base Duty

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cux350z
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Joined: Mon Mar 28, 2011 5:06 am

Control Start Pressure and Closed Loop Base Duty

Postby cux350z » Wed Mar 30, 2011 9:40 am

My situation:

I recognize a few of the names here so I wont go into 100% of my details...you already should know them!

I have 5lb wastegate springs but want to run up to 15+lbs of boost. I am using the Haltech as my boost controller. Currently tuned for 8psi. PID settings are 75,0,0 and 20% base. I have the control start pressure set to 5psi and will probably increase it to the max 7.3psi since I want to keep my WG shut for as long as possible.

does the haltech start at 100% and work its way down? It doesnt appear so when I data log.
does the Haltech rely on the base duty cycle for max pressure? After thinking about it I think it does. I started with 40%DC and had overboost issues ( also had P set to 25)

Will the haltech be able to hold boost upwards 15psi? This I am not certain of with my 5psi springs since the boost controller does not seem to apply boost pressure to the top of the wastegate until the boost is within the target boost range below the set point.

Would I have to slowly step the boost up with rpm...say between 3k and 3500rpm...5,8,10,12,15 ect?
or will increasing the base duty cycle make it work?










or should I just use open loop?

TuRBo-Shark
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Re: Control Start Pressure and Closed Loop Base Duty

Postby TuRBo-Shark » Thu Mar 31, 2011 7:53 am

Closed Loop Tuning
Basic Closed Loop Setup Procedure
The Basic Setup Procedure is a guide on how to get some basic parameters in place to allow the closed loop boost controller to operate.

It is assumed that all the target boost levels are above the wastegate spring pressure. The electronic boost controller cannot control boost below the wastegate spring pressure.

Choose Closed Loop for the Control Type.
Set the frequency of the Turbo Waste Gate solenoid in the ‘Frequency’ setting. The Haltech waste gate solenoid runs at a frequency of 20 – 30 Hz.
Disable the controller by setting Proportional – 0%, Integral – 0% and Derivative – 0%.
Set the ‘Control Point Before Target’ to the default value of 20 kPa (3 PSI).
Set the ‘Delay till Boost Control’ to the default value of 0.5 sec.
Set the ‘Target Boost’ table at the boost level that you want to run across the whole RPM range.
Set the ‘Start Duty’ to a duty cycle that should get you close to your boost target. Start at a small duty, then slowly increase to avoid overboosting.
Put the engine under sufficient load (i.e. on a dyno) to get it to reach the target boost level. Watch to make sure it does not over boost. View the duty cycle of the wastegate, by displaying the Duty channel of the output that the boost controller is setup on. E.g. If boost control is setup on DPO1, then view Digital Pulse Output 1 Duty. If the boost level exceeds the target boost level reduce the ‘Start Duty’, if the boost is far away from the target boost level, then increase ‘Start Duty’. The final value should allow boost to come close to, but just below the target boost level. If Start Duty is set too high, the controller will spike when coming on boost. If it is set too low, then it will start low and slowly rise to the target.
Once you are satisfied with your Start Duty setting, turn on the controller by restoring the Proportional, Integral and Derivative to the following settings:
Proportional - 50%
Integral - 0%
Derivative - 0%
Adjust Proportional until your boost starts to oscillate. Once you find this value, set the Proportional to about half this value. While tuning this value, your boost may still not hit the target boost exactly. This is normal at this stage.
Once you are satisfied with your Proportional setting, start increasing the Integral value until the target boost is close enough to the target level that you wish to run.
Once Proportional and Integral are set, check to see if you have any overshoot when hitting the target. If you have some overshoot, then increase Derivative until that overshoot is minimised. Use caution when increasing Derivative as this setting is very sensitive and should be increased very slowly otherwise, unstable boost control may result.
Setup of the Start Duty Map
If the Target Boost is varying over RPM, or by either a boost trim or gear boost correction then it is a good idea to setup the ‘Start Duty’ table. The Start Duty is closedly related to the target boost, so a different Start Duty for each Target Boost will allow better control over boost levels.

It is assumed that all the target boost levels are above the wastegate spring pressure. The electronic boost controller cannot control boost below the wastegate spring pressure.

Firstly leave the ‘Use Start Duty Table’ un-ticked. Set the entire ‘Target Boost’ table to the lowest desired boost level that you wish to run.
Use the above procedure for setting up Basic Closed Loop Setup Procedure and stop at step 8. Record the ‘Start Duty Cycle’ and the corresponding Target Boost. Increment the ‘Target Boost’ by about 20 kPa (3 PSI) and repeat steps 6 to 8 and record the ‘Start Duty Cycle’ and the corresponding Target Boost again. Repeat this procedure until you reach the max boost that the engine is going to run. You should have a table of Start Duty values against Target Boost levels every 20kPa or 3psi.
Fill out the ‘Start Duty’ table with the data recorded. For the Target Boost Level columns above the highest target that you wish to run, use the highest value Start Duty that you have recorded. For the Target Boost Levels below the lowest target that you wish to run, taper off the Start Duty values below this column until you reach zero duty when at the wastegate spring pressure column.

In the example above, the maximum boost was 140kPa, with the Start Duty values levelled off above this Target Boost. 100kPa is the minimum Target Boost and the Start Duty values below this are tapered off down to around 50kPa.


Tick the ‘Use Start Duty Table’ in the closed loop boost control setup.
(Optional) To fine-tune the ‘Start Duty’ table, setup a closed boost control trim under the analog input function page and load up the engine at different boost levels to make sure that the boost control runs smoothly.

cux350z
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Joined: Mon Mar 28, 2011 5:06 am

Re: Control Start Pressure and Closed Loop Base Duty

Postby cux350z » Thu Mar 31, 2011 11:08 am

Copy paste = Not very helpful. I understand how to tune the BC just need to know how the haltech functions. I would think it would shut the boost solenoid(100% DC) once it detects boost until the amount of boost is between the target boost and 'Control Start offset pressure' and then it would start to control the pressure.

'Delay till Boost Control’ does not exist for me.

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Ignition
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Re: Control Start Pressure and Closed Loop Base Duty

Postby Ignition » Thu Mar 31, 2011 12:27 pm

You should have it plumbed up so that 0% duty is wastegate spring pressure only, I would have thought. You could enter 100% in the start duty table below the point where it starts making boost in order to help things along I guess... I didnt really read that wall of text either, to be fair.

I set boost in open loop first, then start near those figures in the closed-loop start duty table.
And I would have thought closed loop would have compensated for altitude somewhat hmm.

Haven't done closed loop control since an E8 so a bit rusty... Everyone keeps buying Sprints. :roll:

TuRBo-Shark
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Re: Control Start Pressure and Closed Loop Base Duty

Postby TuRBo-Shark » Thu Mar 31, 2011 4:54 pm

cux350z wrote:Copy paste = Not very helpful. I understand how to tune the BC just need to know how the haltech functions. I would think it would shut the boost solenoid(100% DC) once it detects boost until the amount of boost is between the target boost and 'Control Start offset pressure' and then it would start to control the pressure.

'Delay till Boost Control’ does not exist for me.


But reading how things works it is and will let you know how the Haltech functions.
100% DC open means that the solenoid bleeds all out, so the wastegate stays closed.
Also 100%DC is not good for a solenoid, you should get maximum bleed at a lower value from witch you won't have enough flow through the solenoid no matter how big the DC is.
So with 0% duty you have spring pressure, increase the DC in small steps and notice what boost you obtain and note the values until you reach the desired boost target .
Now put that values in the duty table and activate closed loop.

Here you have how to plumb in the solenoid :http://www.haltech.com.au/wp-content/uploads/2011/01/HALTECH-BOOST-CONTROL-SOLENOID.pdf

cux350z
Posts: 25
Joined: Mon Mar 28, 2011 5:06 am

Re: Control Start Pressure and Closed Loop Base Duty

Postby cux350z » Thu Mar 31, 2011 9:12 pm

I do not have it plumbed like that. My breather filter is the one on the face and the supply and feed lines are the ones on the side. I put the top of the wastegates to the normally open port to the filter. When the sv is activated the top port of the wastegates sees the manifold pressure. The little piece of paper that came with the SV had 3 ways to plumb it.

100% is not harmful to the SV...all it means is constant 12v.


Ignition wrote:You should have it plumbed up so that 0% duty is wastegate spring pressure only, I would have thought. You could enter 100% in the start duty table below the point where it starts making boost in order to help things along I guess... I didnt really read that wall of text either, to be fair.

I set boost in open loop first, then start near those figures in the closed-loop start duty table.
And I would have thought closed loop would have compensated for altitude somewhat hmm.

Haven't done closed loop control since an E8 so a bit rusty... Everyone keeps buying Sprints. :roll:


That is how I have it plumbed. Disconnect the SV from haltech wiring harness and only get wg spring pressure.

No such thing as start duty or at least I have not seen it. I do have a closed loop base duty cycle though.


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