WGDC questions about overboosting

[dustwhyn]

Hey guys, I recently installed a Pure900 and I'm currently doing an e-tune with PureBoost. We've been going back and forth over a handful of revisions now trying to sort out an issue that he's seeing with my car and I was hoping that maybe someone here may be able to give me some insight.

He asked if I had done an "EWG module adaptation" after the turbo install, because the car is overboosting in the high RPM range despite him having reduced the WGDC quite a bit. He said it looks like "a EWG setting on the stiff side or hanging wastegate".

I'm not getting any DTCs regarding the EWG being out of calibration, so I'm not really sure where to begin. I read a post somewhere on here where someone mentioned that WGDC should be at 100% at idle with the EWG raw position at 0mm. Not sure if that's factual or not, but my WGDC is at 100% at idle and the raw position is reading at around 6.5-6.6mm.

I've spoken to a buddy of mine who works at Pure Turbos and he also seems to think that I need to reset the adaptations for the EWG, but I'm not sure how to do this because I don't see an option for it from within the MHD app. I'm assuming it's an ISTA thing, so if someone can give some insight that would be greatly appreciated.

Here's my Datazap with all of the logs I've taken so far in case anyone is willing to check them out and provide some insight.
https://datazap.me/u/dustwhyn

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[razorlab]

Is your downpipe vband rotated correctly so the WG arm doesn’t hit it?

 

[dustwhyn]

Is your downpipe vband rotated correctly so the WG arm doesn’t hit it?

Yeah, I made sure to put the bolt on the bottom where it would be out of the way.

 

[kfer]

I checked mine and it's at about 3mm for 100% and runs perfectly.
What I find strange in your log is that the target load is at 230 (which would be completely normal with a Pure Turbo, however the boost target seems not to match the requested load ) but the current load is only at 180-190. There must be a reason why he can't achieve this.
I see WG more as a consequence because he programmed the WGDC for ~24-26PSI (that would be ~230 load at WOT if I look at my map) but does significantly less, so the turbo delivers too much air and the WGDC must be go down (plus throttle closure ).
What I also find strange is, that you have codes 3 and 4 under RF Max. The 3 stands for HPFP and I saw it when we switched to E20 and the pump couldn't deliver enough fuel in the lower rpm range and my Load was also limited.
Are you using the stock HPFP?

 

[dustwhyn]

I checked mine and it's at about 3mm for 100% and runs perfectly.
What I find strange in your log is that the target load is at 230 (which would be completely normal with a Pure Turbo, however the boost target seems not to match the requested load ) but the current load is only at 180-190. There must be a reason why he can't achieve this.
I see WG more as a consequence because he programmed the WGDC for ~24-26PSI (that would be ~230 load at WOT if I look at my map) but does significantly less, so the turbo delivers too much air and the WGDC must be go down (plus throttle closure ).
What I also find strange is, that you have codes 3 and 4 under RF Max. The 3 stands for HPFP and I saw it when we switched to E20 and the pump couldn't deliver enough fuel in the lower rpm range and my Load was also limited.
Are you using the stock HPFP?

Interesting. I’ll have to grab a copy of ISTA and run the wastegate diagnostics and see what the result is, then. He’s actually not trying to hit that boost level from what he’s told me, he explained to me that he keeps removing duty cycle from the wastegate to try to bring the boost level down and the car just continues to make more boost than it should no matter what he does. I’m on the stock HPFP for now and we haven’t even made it to ethanol tuning yet. This is all just ACN91 so far.

 

[razorlab]

I checked mine and it's at about 3mm for 100% and runs perfectly.
What I find strange in your log is that the target load is at 230 (which would be completely normal with a Pure Turbo, however the boost target seems not to match the requested load ) but the current load is only at 180-190. There must be a reason why he can't achieve this.
I see WG more as a consequence because he programmed the WGDC for ~24-26PSI (that would be ~230 load at WOT if I look at my map) but does significantly less, so the turbo delivers too much air and the WGDC must be go down (plus throttle closure ).
What I also find strange is, that you have codes 3 and 4 under RF Max. The 3 stands for HPFP and I saw it when we switched to E20 and the pump couldn't deliver enough fuel in the lower rpm range and my Load was also limited.
Are you using the stock HPFP?

I'm pretty sure the tuner is dropping base WGDC via the feed-forward table to try and see what's going on. Turbine P-Gain isn't very far off from base so the DME isn't adding a ton of upward PID correction. Also, the boost target is 21 psi when the boost is 25psi+

Remember that load requested/target is a ceiling basically. Lot's of other factors/tables go into accomplishing actually hitting that load than just the load request tables.

Fill Limit 3 can be tripped well before hitting 126* on the HPFP, depending on how other tables are tuned.

 

[kfer]

Remember that load requested/target is a ceiling basically. Lot's of other factors/tables go into accomplishing actually hitting that load than just the load request tables.

As far as I know the boost target will be derived from requested load and other tables. I have had also overboosting, but if it was there then the situation was the following : boost>boost target AND load act>load requested. But in this case the act. load is 30% below the requested (230) but the boost is over the target.
Even that is what I never saw before (I mean overboosting without reaching the target).
What could cause that ? It seems to be unbalanced.

 

[razorlab]

As far as I know the boost target will be derived from requested load and other tables. I have had also overboosting, but if it was there then the situation was the following : boost>boost target AND load act>load requested. But in this case the act. load is 30% below the requested (230) but the boost is over the target.
Even that is what I never saw before (I mean overboosting without reaching the target).
What could cause that ? It seems to be unbalanced.

That is literally the question of this thread.

It seems a mechanical issue in that it isn't being controlled via DME.

As an aside, there are a ton of tuners that use requested load/torque as ceilings and use other tables to keep boost in check.

A lot has been stated that the DME does not use a "traditional" WGDC table but that is not correct. The feed-forward table is exactly that, and depending on the strategy you set in the PID tables, it can follow that table without corrections, if that is what is wanted.

 

[dustwhyn]

It seems a mechanical issue in that it isn't being controlled via DME.

Just ran the service function in ISTA about a dozen times with the same result every time. No faults identified and it does not give me any sort of adjustment numbers so I’m assuming the calibration is dead-on. I never messed with the adjustment when installing the turbo, so this result makes sense. I don’t see or hear anything binding when the wastegate actuator moves either. I really don’t know what else to check.

Edit:
Added a couple more logs to the pool on Datazap. Ran a mixed log on my most current revision after messing with ISTA just to see if it may have changed anything behind the scenes, still overboosting. Also ran a 4th gear log on the MHD Stage 2 OTS just to try to help indicate whether or not its a hardware issue and it was overboosting there as well. My most recent stock turbo log was posted on my Datazap on July 31st and I wasn't overboosting there. I'm honestly not sure where to go from here.

 

[kfer]

A lot has been stated that the DME does not use a "traditional" WGDC table but that is not correct. The feed-forward table is exactly that, and depending on the strategy you set in the PID tables, it can follow that table without corrections, if that is what is wanted.

If I understand it correctly, the control logic points to a "distribution factor" and you have a "MAF" value that the DME wants to make for the desired load.
But as I can see from your values you have an upgrade turbo that can do around 650-700BHP(?) , so you have to fill that table with your own values. How did you do that ? Did you get a compressor characteristic from the turbo manufacturer to fill the table or did you just try around until it worked properly?

 

[kfer]

Added a couple more logs to the pool on Datazap. Ran a mixed log on my most current revision after messing with ISTA just to see if it may have changed anything behind the scenes, still overboosting. Also ran a 4th gear log on the MHD Stage 2 OTS just to try to help indicate whether or not its a hardware issue and it was overboosting there as well. My most recent stock turbo log was posted on my Datazap on July 31st and I wasn't overboosting there. I'm honestly not sure where to go from here.

I think overboosting with upgrade Turbo and MHD OTS is completely normal. This is actually exactly the situation that @razorlab showed above. The WGDC table is tailored to the stock turbo, but you have a larger one that delivers significantly more air at the specified WGDC. This leads to overboost.

What I still don't understand is why you always have RF Max "3" and "4" code in your mixed log even during the cruising and not just at WOT . That shouldn't be there and has to do with the fueling.
Show Fabian the codes, maybe he hasn't looked at it yet and is only busy with overboost/wastegate.
https://ecutek.atlassian.net/wiki/spaces/SUPPORT/pages/469270529/BMW+Limit+Flags+States

 

[razorlab]

Just ran the service function in ISTA about a dozen times with the same result every time. No faults identified and it does not give me any sort of adjustment numbers so I’m assuming the calibration is dead-on. I never messed with the adjustment when installing the turbo, so this result makes sense. I don’t see or hear anything binding when the wastegate actuator moves either. I really don’t know what else to check.

Edit:
Added a couple more logs to the pool on Datazap. Ran a mixed log on my most current revision after messing with ISTA just to see if it may have changed anything behind the scenes, still overboosting. Also ran a 4th gear log on the MHD Stage 2 OTS just to try to help indicate whether or not its a hardware issue and it was overboosting there as well. My most recent stock turbo log was posted on my Datazap on July 31st and I wasn't overboosting there. I'm honestly not sure where to go from here.

It almost looks like boost creep, which is what happens when the wastegate can't flow enough to keep up with the demand to maintain lower boost. I wonder if other Pure900's have this same thing happening? Has your tuner tuned other Pure 900's before? They are so new to the market.

The only ones I have seen so far are high boost ethanol efforts.

Have you seen what kind of boost it gets with 0 WGDC where it starts creeping up in boost? If it were me, I would run 0 WGDC and see what the turbo does naturally.

 

[razorlab]

If I understand it correctly, the control logic points to a "distribution factor" and you have a "MAF" value that the DME wants to make for the desired load.
But as I can see from your values you have an upgrade turbo that can do around 650-700BHP(?) , so you have to fill that table with your own values. How did you do that ? Did you get a compressor characteristic from the turbo manufacturer to fill the table or did you just try around until it worked properly?

Distribution factor is the distribution of exhaust going through the wastegate or the turbine. Lower numbers mean less is going through the turbine (less boost) and higher numbers mean more is going through the turbine (mo boost). The compressor map shifts the distribution factor as the compressor map is essentiality turbine power in Kw. So as you request more Kw power in the Compressor map, you go up in the distribution factor. So when tuning a boost curve, you take both tables into account. Every tuner has a different strategy but I tend to set the base boost curve using the Feed-Forward table with all PID controls turned off. This allows me to get the boost level/curve I want very close with base WGDC before any PID functions change things. Then I turn the PID tables back on and fine tune those tables.

You won't get compressor maps from any of these third party hybrid turbo manufacturers, I doubt they even have them themselves. Even if you were able to, usually published compressor maps are by pressure ratio and lb/min and are mapped a bit differently than the DME "compressor map".

 

[TurboZX10R]

I agree with Razorlab and I think this is definitely wastegate related.

 

[dustwhyn]

I think overboosting with upgrade Turbo and MHD OTS is completely normal. This is actually exactly the situation that @razorlab showed above. The WGDC table is tailored to the stock turbo, but you have a larger one that delivers significantly more air at the specified WGDC. This leads to overboost.

What I still don't understand is why you always have RF Max "3" and "4" code in your mixed log even during the cruising and not just at WOT . That shouldn't be there and has to do with the fueling.
Show Fabian the codes, maybe he hasn't looked at it yet and is only busy with overboost/wastegate.
https://ecutek.atlassian.net/wiki/spaces/SUPPORT/pages/469270529/BMW+Limit+Flags+States

I figured it would still overboost on the OTS but I wanted to test it just to be sure and add more data to the pot.

I’m sure Fabian is keeping an eye on everything, but he seems to be fixated on the overboosting issue right now, so only time will tell. It’s not like this is his first rodeo, but it may be his first time tuning the Pure900, I’m not sure.

It almost looks like boost creep, which is what happens when the wastegate can't flow enough to keep up with the demand to maintain lower boost. I wonder if other Pure900's have this same thing happening? Has your tuner tuned other Pure 900's before? They are so new to the market.

The only ones I have seen so far are high boost ethanol efforts.

Have you seen what kind of boost it gets with 0 WGDC where it starts creeping up in boost? If it were me, I would run 0 WGDC and see what the turbo does naturally.

We haven’t tried 0 WGDC yet. After I ran the EWG service function in ISTA, he wanted me to re-run the Rev6 logs even though ISTA said the EWG was fine. Waiting to hear back from him on what’s next.

Regarding other Pure900’s, I have two friends who also have them. One is on a 2-port Supra (Pure Turbos’ test car) that was tuned on EcuTek by Zach from CounterSpace Garage and the other is another M340i on bm3 being tuned by Paul Johnson. The 2-port car seems to occasionally exhibit similar boost behavior with regards to overshooting the target in the higher RPM range, but when comparing logs, we’ve also noticed a correlation between ignition timing and the overboosting issue. The only time he ever really overboosts is if timing up top happens to be pulled a bit for whatever reason. He said he spoke to Zach and he described it as normal behavior because the DME is trying to compensate so that it can still hit the power target. The other M340i doesn’t seem to have this issue, but his logs show pretty consistent timing all throughout the rev range. He’s also a little bit of a different story than the other two cars because he’s running an AA catted downpipe instead of catless, and he also has the DS25-350 and S58 injectors, with his base fuel being 93 octane.

I agree with Razorlab and I think this is definitely wastegate related.

In what regard though? Are you thinking it’s related to the tuning aspect of the wastegate, or something on the physical side? Everything moves freely. No blockages or binding or sluggish movement as far as I can tell.

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