Dano's Boost Tuning 101 + Cool Stuff

[Meder]

My car on full boost tuning does not seem to be affected by bec.

At this point is it best to fill in LEC and trl x gear tables for a "hybrid" tune? Do i need to change other load tables?

2008 ms3 - intake/dp.

[rfinkle2]

It would be time consuming, but I'm sure we could get a car to volunteer, and we could somehow share the map and its affects on each table, shoot ideas back in forth etc. in a dedicated thread.

[Caboose]

So what's the max reliable limit hp wise, right now for load tuning? Given the circumstances?

[Lex]

Originally Posted by Dano Wastegate Controller is a Proportional Integral Derivative controller (PID). P = Boost/Load Error Compensation I = Boost Error Limiter D = RPM compensation switch

Dan, have you tried traditional PID tuning using the above definition?

Although the table names don't make much sense, if you have a growing consistent error the I should be ramped up.

Originally Posted by Caboose So what's the max reliable limit hp wise, right now for load tuning? Given the circumstances?

Seems somewhere along 2.0-2.1 load at redline which should be ~380+whp. The caveat is that this is on gasoline and not E85 where the MAF must be scaled and the load values are artificially high. But that doesn't have much to do with reliability - just has to do with what the ECU seems to allow using load tuning.

[silvapain]

Originally Posted by Dano Wastegate Controller is a Proportional Integral Derivative controller (PID). P = Boost/Load Error Compensation I = Boost Error Limiter D = RPM compensation switch

Those are not correct for a proper PID. An integral would be the sum of boost over a set time range (the area under the curve, so to speak). A derivative would be the change in boost over time (the slope of the boost line). We don't have access to either of those.

Based on what we can currently see, we have two proportional controllers in series with a switch to go between them.

Just semantics, but I'm picky on that kind of stuff.

[Lex]

Originally Posted by silvapain Those are not correct for a proper PID. An integral would be the sum of boost over a set time range (the area under the curve, so to speak). A derivative would be the change in boost over time (the slope of the boost line). We don't have access to either of those. Based on what we can currently see, we have two proportional controllers in series with a switch to go between them. Just semantics, but I'm picky on that kind of stuff.

This is what I have a problem with - the the confusing table names in ATR. If those are somehow PID terms the names are def not right. This is why I was asking - has anyone tried using those tables as PID terms?

[Dano]

Originally Posted by Lex Dan, have you tried traditional PID tuning using the above definition? Although the table names don't make much sense, if you have a growing consistent error the I should be ramped up.

so I is the LEC/BEC Ramp Limit which is never reached because no correction is even applied, right?

and no this is the first car I have messed with...what a platform to cut your teeth on lol

[rfinkle2]

Would "P" would be the comp table @ a given error, the "I", the summation of the boost error comp loop, and is the "D" the variable that creates the problem in a true "PID"?

[Lex]

Originally Posted by Dano so I is the LEC/BEC Ramp Limit which is never reached because no correction is even applied, right? and no this is the first car I have messed with...what a platform to cut your teeth on lol

The actual PID controller definitions are as follows. This is what the terms should do if indeed they are the PID terms. Link from NI site: PID Theory Explained - Developer Zone - National Instruments

Cole's notes:
- P term is a simple gain. The difference between desired and actual is multiplied by this gain and applied to the system to get desired and actual closer together

- I term is the sum of error over time. As time goes by this sum increases if there is an error and applies a stronger action to the actuator to reduce error

- D term is the derivative - rate of change. It sets how harshly the controller responds to an error - this can cause spikes and oscillations.

Proportional Response
The proportional component depends only on the difference between the set point and the process variable. This difference is referred to as the Error term. The proportional gain (Kc) determines the ratio of output response to the error signal. For instance, if the error term has a magnitude of 10, a proportional gain of 5 would produce a proportional response of 50. In general, increasing the proportional gain will increase the speed of the control system response. However, if the proportional gain is too large, the process variable will begin to oscillate. If Kc is increased further, the oscillations will become larger and the system will become unstable and may even oscillate out of control.

Integral Response
The integral component sums the error term over time. The result is that even a small error term will cause the integral component to increase slowly. The integral response will continually increase over time unless the error is zero, so the effect is to drive the Steady-State error to zero. Steady-State error is the final difference between the process variable and set point. A phenomenon called integral windup results when integral action saturates a controller without the controller driving the error signal toward zero.

Derivative Response
The derivative component causes the output to decrease if the process variable is increasing rapidly. The derivative response is proportional to the rate of change of the process variable. Increasing the derivative time (Td) parameter will cause the control system to react more strongly to changes in the error term and will increase the speed of the overall control system response. Most practical control systems use very small derivative time (Td), because the Derivative Response is highly sensitive to noise in the process variable signal. If the sensor feedback signal is noisy or if the control loop rate is too slow, the derivative response can make the control system unstable


Tuning
The process of setting the optimal gains for P, I and D to get an ideal response from a control system is called tuning. There are different methods of tuning of which the “guess and check” method and the Ziegler Nichols method will be discussed.

The gains of a PID controller can be obtained by trial and error method. Once an engineer understands the significance of each gain parameter, this method becomes relatively easy. In this method, the I and D terms are set to zero first and the proportional gain is increased until the output of the loop oscillates. As one increases the proportional gain, the system becomes faster, but care must be taken not make the system unstable. Once P has been set to obtain a desired fast response, the integral term is increased to stop the oscillations. The integral term reduces the steady state error, but increases overshoot. Some amount of overshoot is always necessary for a fast system so that it could respond to changes immediately. The integral term is tweaked to achieve a minimal steady state error. Once the P and I have been set to get the desired fast control system with minimal steady state error, the derivative term is increased until the loop is acceptably quick to its set point. Increasing derivative term decreases overshoot and yields higher gain with stability but would cause the system to be highly sensitive to noise. Often times, engineers need to tradeoff one characteristic of a control system for another to better meet their requirements.

The Ziegler-Nichols method is another popular method of tuning a PID controller. It is very similar to the trial and error method wherein I and D are set to zero and P is increased until the loop starts to oscillate. Once oscillation starts, the critical gain Kc and the period of oscillations Pc are noted. The P, I and D are then adjusted as per the tabular column shown below.

[Dano]

Originally Posted by silvapain Those are not correct for a proper PID. An integral would be the sum of boost over a set time range (the area under the curve, so to speak). A derivative would be the change in boost over time (the slope of the boost line). We don't have access to either of those. Based on what we can currently see, we have two proportional controllers in series with a switch to go between them. Just semantics, but I'm picky on that kind of stuff.

oh I think it is more than semantics and the defined "logic" isn't correct. What you say does make sense in that two separate controllers, one targeting load and another targeting boost, work together and the RPM Comp "switch" switches between the two.

so what happens on my "pure boost" tunes that dont work is somehow the control gets switched to the load controller and thus no DC alteration occurs for a period of time, if at all.

your def actually makes perfect sense.

the trouble is it doesn't happen to all cars even if they are the same year model so unless the ECU vendor is drastically changing the logic your def doesn't fit for all ECUs.

good stuff

[silvapain]

If you want to use a PID tuning method for boost, use the Zeigler-Nichols method. That's what I use for tuning PID's for process automation (I'm a process automation engineer). A straight P controller will show periodic oscillations. A straight D controller will always have steady-state error. I have never seen a straight I controller.

I have seen in my experience tuning Ford Taurus SHOs using SCT is that even within the same model year the OEM will have multiple ECU programs that are slightly different. We may be seeing symptoms of different PCM codes.

In the SHO world, the PCM code was printed on a label that was on the PCM itself.

[kritz]

Al this process control talk is giving me a woodie, I am a plumber and play with DDC BMS, and pneumatic controls.

[Boosted Beluga]

As everyone starts looking for codes on the ecu

[rfinkle2]

I'll admit, I never used pids @ my job, I just like boost and fast cars.

[superskaterxes]

this one time

i used an MBC

because racecar

[djuosnteisn]

Originally Posted by silvapain Exactly. 100% E85 guys can't use load tuning at all. There are undiscovered tables at play that limit the throttle plate and WG long before we hit load targets. I was getting 0 WGDC and TP closing with fuel cut at 3.2 load when my targets were 4.05 load with the OTS LEC table values. Tapadatass

Have you tried load tuning with the BT toggle enabled? LEC is always functional... i'm curious on the results.

Originally Posted by cld12pk2go Speaking of going midevil... I am fighting the AP Load Cap V2™ where load falls off up top down to ~2.1 at 6500 RPMs regardless of any boost or load table values (using either of the two load targeting strategies). The map I am loading this morning is going to test to I can get around this by limiting the "WG Duty Boost Error Ramp Limiter - Low Limit" and "WG Duty Load Error Ramp Limit - Low Limit" from -100% to -20% such that my top end shouldn't have authority to limit power up top as much. This is obviously playing with fire, but my WGDC tables are configured such that I should only be ~3% higher than my logged WGDC from yesterday if this works. TBD if this is a workable solution. If not, then I guess I am back to the old school MAF curve lightening bolt + rich fueling tables to try to work around it.

Same question for you lol.

[silvapain]

Originally Posted by djuosnteisn Have you tried load tuning with the BT toggle enabled? LEC is always functional... i'm curious on the results.

When I started tuning for E85 I was hybrid tuning with BT enabled. I had no problems hybrid tuning on pump gas.

[djuosnteisn]

Yeah, i'm just curious if it disables the "mystery" load table that has been kicking all us load tuners in the crotch. According to David it does... and also according to David... LEC is in the logic no matter what.... so technically you can load tune just fine with BT toggle enabled.

It's worth a shot IMO. And you understand this stuff excellent, so your in a great position to determine if it works or not.

Originally Posted by silvapain When I started tuning for E85 I was hybrid tuning with BT enabled. I had no problems hybrid tuning on pump gas.

Wait... unless your saying that you still had problems with the BT toggled.... i'm not sure i interpreted this right lol.

So it's no bueno? Was this on the latest ATR update as well?

[silvapain]

Originally Posted by djuosnteisn Yeah, i'm just curious if it disables the "mystery" load table that has been kicking all us load tuners in the crotch. According to David it does... and also according to David... LEC is in the logic no matter what.... so technically you can load tune just fine with BT toggle enabled. It's worth a shot IMO. And you understand this stuff excellent, so your in a great position to determine if it works or not. Wait... unless your saying that you still had problems with the BT toggled.... i'm not sure i interpreted this right lol. So it's no bueno? Was this on the latest ATR update as well?

No bueno. With BT checked I still had to make my load targets completely unreachable to prevent LEC from interferring. I was maxing out at 3.1-3.2 calculated load with a target of 4.05 load and I was still seeing the TP close and WGDC drop. My AFR's went wonky too.

See attached. (Boost target was 21psi)

[djuosnteisn]

Lol, you have shark-fin-esque WGDC in that log too. What were your AFR targets?


I know that at this altitude, you have to command much higher load than you intend on running... For instance, if you set your calc load max to 3... it'll really clip at 2.4 (roughly 20% lower than intended). And if you wanna target 2.4 load... you have to command 3's.

As i understand it... baro is one of the last things the ecu does for a load calc, and i wonder if the cooler air is playing a role.

I dunno... but your log is pretty disappointing....

[Dano]

Originally Posted by Meder My car on full boost tuning does not seem to be affected by bec. At this point is it best to fill in LEC and trl x gear tables for a "hybrid" tune? Do i need to change other load tables? 2008 ms3 - intake/dp.

for now, if your car won't follow pure BT then you will want to run a hybrid tune.

check the BT toggle but you'll need to populate LEC/LD then tune your TRL's to within .05 of logged load at your preferred boost target.

so basically you are load tuning lol

I am cutting a map right now for @Boost_creep that hopefully will show some movement with WGDC and offer a temp solution to this issue....i am not holding my breath lol

What is strange in his situation is targets are met and hold until around 5K...what voodoo is happening at 5k IDK.

[cld12pk2go]

Originally Posted by djuosnteisn Have you tried load tuning with the BT toggle enabled? LEC is always functional... i'm curious on the results. Same question for you lol.

Nope, I have avoided Boost Targeting thus far since it is a greatly inferior tuning method IMHO. I am just looking for a backdoor to make Load Targeting work until Cobb realizes how huge of an issue this is for us and allocates some resources to resolve it.

[silvapain]

Originally Posted by djuosnteisn Lol, you have shark-fin-esque WGDC in that log too. What were your AFR targets? I know that at this altitude, you have to command much higher load than you intend on running... For instance, if you set your calc load max to 3... it'll really clip at 2.4 (roughly 20% lower than intended). And if you wanna target 2.4 load... you have to command 3's. As i understand it... baro is one of the last things the ecu does for a load calc, and i wonder if the cooler air is playing a role. I dunno... but your log is pretty disappointing....

0.81 lambda (11.9 on pump gas scale).

My logged baro is pretty typical for my area based on my datalog history.


Tapadatass

[Dano]

Originally Posted by cld12pk2go Nope, I have avoided Boost Targeting thus far since it is a greatly inferior tuning method IMHO. I am just looking for a backdoor to make Load Targeting work until Cobb realizes how huge of an issue this is for us and allocates some resources to resolve it.

but doesn't checking the BT toggle eliminate the load cap? Isn't that what dustin does...or does he do that and use an MBC?

it certainly doesn't eliminate load targeting...sooooo maybe try the toggle and set boost targets out of reach an load tune as normal.

zero BEC

[silvapain]

Originally Posted by Dano but doesn't checking the BT toggle eliminate the load cap? Isn't that what dustin does...or does he do that and use an MBC? it certainly doesn't eliminate load targeting...sooooo maybe try the toggle and set boost targets out of reach an load tune as normal. zero BEC

The calculated max load tables remove the load cap (supposedly). At least for me, I'm calculating load fine, it's just that LEC is intervening before my load target tables tell it to.


Tapadatass

[Dano]

I thought the guys having trouble saw the TPS close and load targets were not being met with 0 WGDC above like 5.5 K.

I realize the old load cap is gone but cld and Dustin have found another.

You may not see it b/c you have BT checked.

Edit:

so perhaps some promice on a pure BT.

looking at boost_creeps latest logs I do see WGDC ramping up now with the higher values in BEC yet still not fast enough.

so larger numbers may work but I have another question.

Why is the ECU not IPing the WGDC RPM breakpoints?

ECU is ramping up from 55s up through the 60s yet when it enters the 60s the commanded DC is 70?

don't get me wrong I would love for BT logic to work like LT logic and you could basically set WGDC wherever you wanted and the comp tables would converge on target but WTF is this chit?

/rant

[rfinkle2]

Originally Posted by Dano I thought the guys having trouble saw the TPS close and load targets were not being met with 0 WGDC above like 5.5 K. I realize the old load cap is gone but cld and Dustin have found another. You may not see it b/c you have BT checked. Edit: so perhaps some promice on a pure BT. looking at boost_creeps latest logs I do see WGDC ramping up now with the higher values in BEC yet still not fast enough. so larger numbers may work but I have another question. Why is the ECU not IPing the WGDC RPM breakpoints? ECU is ramping up from 55s up through the 60s yet when it enters the 60s the commanded DC is 70? don't get me wrong I would love for BT logic to work like LT logic and you could basically set WGDC wherever you wanted and the comp tables would converge on target but WTF is this chit? /rant

I question this as well. It is sometimes as if it is the overall wgdc ramp (i.e. the change in columns as interpolated) is used as part of the ramp limit.

e.g., if moving from 50-60, you are using up, for lack of a better term, 20% of the ramp limit.

[cld12pk2go]

Looks like my test today was pure fail...



All load tables were targeting 2.35 from 3500-7000 RPMs.

Not only was WGDC at 6500 RPMs 25% below the 88% in the WGDC table (the ECU pulled more than the -20% in my limit tables), but the throttle started to close up top as well for no apparent reason, which i have never seen before and shouldn't happen based upon the tables we have access to...

Maybe it is Boost Targeting time for me...

The only other thing I can think of is I am at 4.9v on my MAF when these oddities occur. I have the CP-E 3.25'' MAF on order, so if pegging the voltage is an issue, that should be eliminated soon.

[Ziggo]

I had the similar issues with boost targeting, it's why I switched to load targeting. My LEC and LD tables were zero, and my boost was below target, but something was holding down my WGDC. Very frustrating.


Zigatapatalka

[Boost_creep]

Originally Posted by Dano for now, if your car won't follow pure BT then you will want to run a hybrid tune. check the BT toggle but you'll need to populate LEC/LD then tune your TRL's to within .05 of logged load at your preferred boost target. so basically you are load tuning lol I am cutting a map right now for @Boost_creep that hopefully will show some movement with WGDC and offer a temp solution to this issue....i am not holding my breath lol What is strange in his situation is targets are met and hold until around 5K...what voodoo is happening at 5k IDK.

Dear ECU,

I'm going to kill you in your sleep.

[Dano]

So I sent Boost_Creep a map with the below BEC table



and it was pure fail.

What it did do was allow him to over boost in the 3-3.5K range then oscillate a bit before falling off in the exact same place as before ~4800 RPMs.

I also sent him a map with WGDC RPM Comp A set to -50 B to 10 with the same results.

something in the 5K + range is not allowing WGDC to ramp up according to the BEC values.

I'll try a higher WGDC BEC High ramp limit next but I seriously doubt it will do anything. The reason is because in the early RPMs I was getting a 15% increase in DC over table values so at that point RL isn't limiting anything but later I do good to get 2% increase in logged DC AND its well below table value.

[Nataphen]

I'm having the same issue with my car and another car that I'm helping tune. I've tried more aggressive underrun figures in the BEC, and that allowed the WGDC to eventually get where I wanted. However, at 5k, my WGDC is 10% lower than commanded (90% commanded), and I'm over 1psi under my boost targets from 5400+. By 5700, my WGDC is up to commanded values, and BEC begins adding WGDC all the way to 100% by 6k, which is 10% above my commanded values.

Before I added the more aggressive underrun values, my WGDC was 15% under commanded at 5k, and would slowly get up to 9% under commanded by 6k. I'm going to keep going up on the underrun values to see if I continue to see improvement, but I'd say that this is a step in the right direction in my case. I'll try it on the other car that I'm tuning and see if I see similar results.

EDIT: I tried getting more aggressive with the values, and that gave me some pretty nasty boost spikes in the low end. On the other hand, it did reduce the amount of time that my WGDC was out of my commanded values. Pics attached from 3 logs, boost targets are 19psi, commanded WGDC is 90%@5k+. It's still not pretty, but it's making some difference for me. I'll keep messing with it and I'll let you guys know if I find anything constructive.

[Nataphen]

Fucking hell, this is irritating. I set BEC to the values shown below, which seemed to work the best so far to reach targets without spiking. There was a brief overrun within 20.5psi in the 3500 range. Not what I like to see, but I was willing to allow that for now if I was reaching WGDC sooner in high RPM.

Then, I changed the RPM comp to -50 and 20 as suggested by silvapain, but that didn't do a damn thing except make it all worse. My low RPM WGDC was running way higher than commanded causing boost to sustain 22psi with 19psi targets. This also made the high RPM WGDC run under commanded values for longer, not allowing me to reach 19psi, nor ever reaching my commanded 90% WGDC before 6k RPM.

The best so far has been this BEC, OTS RPM comp A&B, and 15% BE ramp high limit. It's cold and rainy now, so I'm having trouble getting even 4th gear logs without wheel spin. This may be all that I can come up with for you guys today.

[Dano]

tis the season to be jolly...fa la, la, la la la la la LOADtuning

[Lex]

Originally Posted by Nataphen I'm having the same issue with my car and another car that I'm helping tune. I've tried more aggressive underrun figures in the BEC, and that allowed the WGDC to eventually get where I wanted. However, at 5k, my WGDC is 10% lower than commanded (90% commanded), and I'm over 1psi under my boost targets from 5400+. By 5700, my WGDC is up to commanded values, and BEC begins adding WGDC all the way to 100% by 6k, which is 10% above my commanded values. Before I added the more aggressive underrun values, my WGDC was 15% under commanded at 5k, and would slowly get up to 9% under commanded by 6k. I'm going to keep going up on the underrun values to see if I continue to see improvement, but I'd say that this is a step in the right direction in my case. I'll try it on the other car that I'm tuning and see if I see similar results. EDIT: I tried getting more aggressive with the values, and that gave me some pretty nasty boost spikes in the low end. On the other hand, it did reduce the amount of time that my WGDC was out of my commanded values. Pics attached from 3 logs, boost targets are 19psi, commanded WGDC is 90%@5k+. It's still not pretty, but it's making some difference for me. I'll keep messing with it and I'll let you guys know if I find anything constructive.

Realistically, look how little difference in actual boost there is between 60% WGDC and 100%.

[Nataphen]

Three 3rd gear pulls with boost targets and commanded WGDC sitting pretty. I will allow @rfinkle2 to explain if he wishes to do so, but basically, I had to add LEC back in. I had already cut a map with LEC populated because I was out of ideas, then finkle shot me a PM with some additional suggestions. I added those changes to the map, and viola. I have to say that I never had this problem when LEC was populated, so that's why I wanted to give it a try.

Maybe @Dano can figure this out and we can switch to BC only, but for now, it would appear that a hybrid tune is the only way to make the WGDC get some act right.

[Nataphen]

Originally Posted by Lex Realistically, look how little difference in actual boost there is between 60% WGDC and 100%.

Oh, there's no doubt I'm tuning a k04 with a stock DP and stock EBC. Adding LEC back in made the WGDC line up with commanded values much more though.

[silvapain]

I have the solution.




















Run 100% WGDC all the time like a boss.


Tapadatass

[Nataphen]

My idea with using 90% is that the BEC SHOULD add enough WGDC to get to 100%, but it will also allow it to pull lower for overboost. Again, that's the idea, but it doesn't seem to be working thus far.

[Dano]

Originally Posted by silvapain I have the solution. Run 100% WGDC all the time like a boss. Tapadatass

if only that would work...boost creeps car completely ignores commanded DC.

Originally Posted by Boost_creep Dear ECU, I'm going to kill you in your sleep.

hahahahah


sounds like the letter I wrote to mine a couple years ago when it wouldn't fuel the car due to the load cap...

ahhhh those were the days when you could trick the ECU into doing what you wanted it to do...alas I don't think we'll be able to trick the ECU [that is every ECU] into following a pure boost targeting logic.