[OpenFlash]

jk about the final showdown part. Just looking to lighten the mood a bit...

Anyway, the other thread has gotten too long and silly. Looking to put it to bed with this thread.

Background:

In the last week or so, two new people have been testing a beta version of v2.0.2. This is in addition to the handful of people who have running it before that. One of these two new people was Eugen.

He believed that there was some boost issues with v2.0.2. He sent me the following datalog in an attempt to illustrate what he believed to be a problem:



Here is his comment:

Originally Posted by e.n335

I saw the boost climbing on the gauge, decoupled from the constant throttle position, minimum load and hoped it will stop soon. It did @ 13.2 psi. I never saw something like this before.

As I understand it, he is basically saying that he didn't expect boost to go up to 13.2psi given the fact that he was at partial throttle.

Here's some technical info explaining why this behavior isn't only normal, it's intentional.

First of all, max desired boost with v2.0.2 is 15psi on pump gas. Default user torque provided will provide 13-14psi max. Users can raise the user torque settings, 2% at a time (across the board), until they acheive this maximum level. It will occur at 5000-5500rpm. This will all be described in the documentation. You will not see big boost spikes just as long as you either leave the default map the way it is OR follow directions (no big changes to the User Torque table).

Boost target is stock below 2000rpm. You can see this on the "Fuel Correction" log. It's misnomer as it actually describes T-MAP signal adjustment. Notice that there is no signal attenuation below 2000rpm and that it gradually ramps until 2800rpm at which point it is making a substantial boost change (13.2psi). This is normal. The reason for not increasing boost below 2000rpm is to avoid the high boost lugging condition that some folks tend to subject their car to (ie, WOT at 1650rpm in a high gear.. yuck).

As for partial throttle position inducing close to full boost, this is normal too. For a number of reasons:

1) First, applied throttle does not mean actual throttle position (at the engine). In a drive-by-wire car such as the BMW, your pedal position is read by the ECU along with RPM, temp, boost target, baro, etc,. The ECU uses all this info to determine what actual throttle opening should be applied. You will notice that, at low RPM, actual throttle opening is far higher than induced throttle (at the pedal). This is an attempt to make the engine feel more "torquey". But at higher engine speeds, actual throttle opening is less than applied throttle to avoid being to "jumpy" when scooting around (think big block with a non-progressive throttle butterfly). All this behavior can be recorded through a basic OBD-II logging software by just comparing Applied Throttle Position to Actual Throttle Position. The PROcede software does not log actual or applied TPS so I don't expect anyone to know this from just using the PROcede logging software.

2) Turbos are not linear devices. They are positive feedback systems. Their speed is controlled by exhaust flow. And exhaust flow is controlled by their speed.

3) Boost pressure will change due to sudden valve timing changes. Sudden changes occur right before and after shifts (esp. in a 6AT car where the ECU uses it to smoothen out shift by reducing torque just after the upshift). This intentional torque reduction through valve timing shift means that airflow through the engine is momentarily compromised. This means that the air builds up in the intake manifold until the wastegates can make the necessary adjustment. This is normal.

4) Boost pressure also changes due to sudden open and closing of the throttle. Closing is a no-brainer. But opening is interesting. When you snap open the throttle, lots of things happen. First, you are sending a signal to the ECU that you want full power. So the ECU responds by:

a) Actually opening the throttle body
b) Adjusting valve/cam timing
c) Applying full vacuum to the wastegate actuators


The throttle opening maximizes airflow through the engine which, in turn, maximizes exhaust production. The valve timing change does it part to maximize exaust velocity as well. The closed wastegates ensures that all that exhaust goes through the turbos (and not out the wastegates). This means that the turbos are now spooling up as fast as possible and boost is rising.

Once boost reaches the max desired pressure (6-9psi stock, 11-15psi PROcede v2.0.2), the following happens:

a) ECU signals the wastegate control solenoids to dial back vacuum which, in turns, opens the wastegates. The opening of the wastegates mean that some exhaust flow is bypassed around the turbo. This bypassing effect slows the rotational acceleration rate of the turbo. More and more exhaust gets bypassed until the turbo reaches a point where it is sustaining the desired boost, not ramping upwards as it was earlier in the process. However, all this takes time. During this time, there is a point were turbo boost may overshoot the boost target. Maybe by 0.25psi. Maybe by 0.5psi. Maybe for 0.1-0.5 seconds. This is normal. You will find this is just about ANY turbo application. Especially in moderate to high boosted applications where we are asking that turbo to go from a few thousand RPM to a few hundred thousand RPM in less than a second! It is possible to compromise boost response in exchange for boost stability. This is also done in just about every boost control strategy you can think of. But there is a balance that must be achieved. If you slow down the response too much, the car will be unnecessarily laggy (which is essentially a negative boost spike). If you speed up the response to much, you will get larger 2-3psi boost spikes. There is a fine line and this is what tuning is.

In the case of v2 PROcede, we adjust the boost response rate as a function of RPM. At RPM extremes (below 3000rpm and above 5000rpm), where boost spiking is unlikely, we speed up boost response to ensure good performance. In the low RPM range, boost spiking is unlikely because there isn't enough exhaust flow to make things get out of hand. And at the top end, the turbos are already approaching their flow limitations and the engine is already approaching its VE limitations. But in the midrange where both the engine and turbos are in their sweet spot, we reduce the boost response rate by 50-60% (how this is quantified is beyond the scope of this discussion). So what you get is minimal to no spiking. In fact, with v2.0.2 if you jump on the gas at 5000rpm, you may even see boost jump immediately to 13psi and then climb, at a slower rate to 14psi with minimal or no spiking. This is also intentional. In other systems which simply adjust boost by adjusting T-MAP (and don't control the solenoids directly), you will always see more obvious boost spiking. Always. But you will need a logging device or a boost gauge to see it.

I hope this email explains things a bit. And I hope that we can keep things technical and on-topic.

Shiv

[RiXst3r]

where does your "automatic 1.5 psi overboost if conditions allow" feature come into play on all this?

Also, how can you expect to properly drive the wastegates under full control by the procede, when it doesnt even monitor/intercept actual or applied throttle position? (not an attack, I just really want to understand)

In my mind, this seems like you are tuning for full throttle, and everything else is just adjusted by the DME? (which no longer drives the wastegates?)

[e.n335]

Originally Posted by e.n335

I checked the datalog again and there is no proof that I did not accelerate moderate to hard. So the only person who knows for sure is me. Now, time will tell if others will experience the same I did. In fact I accelerated in a way that should give me 8-9psi ( I did this often yesterday, tested for about 150 miles, 3 hours ) and boost kept climbing up to 13.3 psi, falling back to 8-9psi. I did not even feel this additional boost.

So you will see whether it occurs or not.

- Eugen

This is a re-posting from the other thread. I hope what I saw is a one-time issue.

- Eugen

[OpenFlash]

Originally Posted by RiXst3r

where does your "automatic 1.5 psi overboost if conditions allow" feature come into play on all this?

Also, how can you expect to properly drive the wastegates under full control by the procede, when it doesnt even monitor/intercept actual or applied throttle position? (not an attack, I just really want to understand)

In my mind, this seems like you are tuning for full throttle, and everything else is just adjusted by the DME? (which no longer drives the wastegates?)

The overboost feature was disabled because in v2.0.2 beta because of confusion that it caused from avid dataloggers.

Intercepting TPS isn't necessary when what we are doing is adding offsets to stock boost performance. We do that by RPM and actual engine load. We also do that by monitoring the duty cycle necessary to achieve a certain boost pressure but that's another story.

We are not tuning for any one condition, be it throttle position, MAP level, RPM, etc,. We are tuning for all conditions.

Shiv

[RiXst3r]

Originally Posted by shiv@vishnu

The overboost feature was disabled because in v2.0.2 beta because of confusion that it caused from avid dataloggers.

Intercepting TPS isn't necessary when what we are doing is adding offsets to stock boost performance. We do that by RPM and actual engine load. We also do that by monitoring the duty cycle necessary to achieve a certain boost pressure but that's another story.

We are not tuning for any one condition, be it throttle position, MAP level, RPM, etc,. We are tuning for all conditions.

Shiv

Boosting to 13 psi at 1/3rd throttle kinda makes it hard to "go easy on your turbos" by just driving around slowly... IMHO you would not be adding useless info by tapping into the TPS and mapping accordingly

[OpenFlash]

Originally Posted by e.n335

This is a re-posting from the other thread. I hope what I saw is a one-time issue.

- Eugen

No. It will happen again and again. Just as long as you induce the same conditions. And this is good and desired. I don't know why you disagree. Although you are perfectly entitled to.

-shiv

[OpenFlash]

Originally Posted by RiXst3r

Boosting to 13 psi at 1/3rd throttle kinda makes it hard to "go easy on your turbos" by just driving around slowly... IMHO you would not be adding useless info by tapping into the TPS

The stock car also sees close to full boost at partial throttle at 2500rpm. Goes back to the whole calculated torque demand scenario. I appreciate your feedback though.

shiv

[RiXst3r]

Originally Posted by shiv@vishnu

The stock car also sees close to full boost at partial throttle at 2500rpm. Goes back to the whole calculated torque demand scenario. I appreciate your feedback though.

shiv

so in your opinion, 13psi at 1/3rd throttle is "good and desired" ?

[OpenFlash]

Originally Posted by RiXst3r

so in your opinion, 13psi at 1/3rd throttle the "desired effect" ?

¥es. 25-30% applied throttle at 2500rpm induces an actual throttle opening of 60-75%. This is to enhance low end torque. BMW thought it was fitting and I see no reason to mess with it. Does it make sense now?

Shiv

[RiXst3r]

Originally Posted by shiv@vishnu

¥es. 25-30% applied throttle at 2500rpm induces an actual throttle opening of 60-75%. Does it make sense now?

Shiv

It made sense before... I just dont know if I want to be driving around boosting to 13+ psi even when trying to drive conservitively

Not everyone is as "balls out" as you are shiv...

[Nikolas]

I want 13 psi at partial throttle as long as it tapers at the end.

[OpenFlash]

Originally Posted by RiXst3r

It made sense before... I just dont know if I want to be driving around boosting to 13+ psi even when trying to drive conservitively

Not everyone is as "balls out" as you are shiv...

Hint: Just use less throttle.

One of the necessary "side-effects" of having a car that makes more power than stock.

shiv

[RiXst3r]

Originally Posted by shiv@vishnu

¥es. 25-30% applied throttle at 2500rpm induces an actual throttle opening of 60-75%. This is to enhance low end torque. BMW thought it was fitting and I see no reason to mess with it. ...

Shiv

but bmw thought it fitting to induce 7-8psi... not 13

you already "messed with it"

[RiXst3r]

Originally Posted by shiv@vishnu

Hint: Just use less throttle. One of the evils of having a car that makes more power than stock.

shiv

More like one of the evils of having a car that makes more boost that the DME is expecting to see

I think i will stop arguing now... you obviously have different goals than me

[Kbueno]

Would you elaborate on the effect of the additional boost/boost spikes with respect to the fuel pump. Will V2 "make your fuel pump fail"?

[OpenFlash]

Originally Posted by RiXst3r

More like one of the evils of having a car that makes more boost that the DME is expecting to see

Give it to me straight. Are you one of those guys that would turn off the M Sport button (if we had one)?

[Ruff Rider]

Shiv, I don't understand all that you have posted here but thank you very much for taking the time out of your day to do so.

People need to see this thread to understand what is going on with the turbos.

[OpenFlash]

Originally Posted by 335lvr

Would you elaborate on the effect of the additional boost/boost spikes with respect to the fuel pump. Will V2 "make your fuel pump fail"?

v2 will not make your pump fail. However, if you have a faulty fuel pump, any tuning system which makes more power (ie, induces more fuel flow) will accelerate the inevitable failure. If you have a good fuel pump (one that is not in the faulty production batch), I don't expect any problems to ever arise with it, v2 or not.

FWIW, I have an early production car (1st month of production) and I'm still on the original fuel pump at 25k miles. All of them running higher boost pressures and fuel demands.

Shiv

[bmwzimmer]

Originally Posted by RiXst3r

More like one of the evils of having a car that makes more boost that the DME is expecting to see

I think i will stop arguing now... you obviously have different goals than me

Is your goal to leave your car bone stock engine wise?

[e90AW335i]

Originally Posted by bmwzimmer

Is your goal to leave your car bone stock engine wise?

I think his goal is not to have 13psi at partial throttle.....

[e.n335]

Does the PROcede V2 max out the fuel system ? If not, what is the remaining safety margin ?

[hotrod182]

Originally Posted by shiv@vishnu

Hint: Just use less throttle.

One of the necessary "side-effects" of having a car that makes more power than stock.

shiv

Why just use more throttle when you want to? This kind of reminds me of the "Sport" button on my M3. Makes the car feel fast and jumpy around down, but does absolutely nothing for all out performance. Most people don't desire this, and don't use the button. I mean, how many people want "on/off" throttle characteristics? I guess it makes the tune "feel" so much faster in everyday driving. I mean if my "sport" button on my M3 made my car faster actually, I would always use it. But just faster at a "given" throttle position, not very useful most of the time. Maybe to lower your fuel economy in everyday driving?