2012 GT throttle "overshoot" on tip-in phenomenon, Edelbrock supercharger

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Originally Posted by murfie

I'm not the one who had to correct my math after seeing the actual PID. Then still couldn't get it exact.

Really of you are approximating do you really need a calculator to turn 100% into 600adc?

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What are you so salty about?

Instead of answering my serious question about why you think pedal voltage is more important / useful; you dodged it and took a jab at me.

When I first derived the math, I didn't have access to the ADC channel. So, I came up with a method to write very distinct values into the driver demand table, observing ETC TQ request and pedal % to approximate the relationship. It's a pretty indirect method, so it shouldn't be surprising that it was slightly off, but I don't think there was a better way. You could read about it in that thread, or just take pot-shots without bothering to read.

Once they added the channel to my strategy, I could observe the two channels together, so obviously that is much more clear. If you are going to be dismissive and insulting, at least be correct. The pedal % runs from 0 - 99.5%, and Pedal AD Count from 0 - 602.4. That doesn't give you 100% = 600 ADC.

Throttle ADC didn't show up in the latest Beta of VCM Suite, so still trying to see if HPT support can help. Regardless, once I get a chance to do some driving and logging, I'll post a log with the current tune and available scanner PIDs.

Sorry for the delay, but I FINALLY had a chance to get back on this. Pedal ADC is now added to the Beta version of VCM Scanner. I created a new log which includes pedal ADC.

Here is my log file:
Attachment 106646

Here is my tune file:
Attachment 106647

Questions:
1) The engine runs "rough" around 1500 RPM at very light throttle. It doesn't misfire...but it's close. You can see it at the beginning of the log. See how the A/F oscillates back and forth? I suspect this might be reversion in the intake manifold or something, as it's only at this specific RPM and throttle position. It's irritating, though. Any ideas?
Attachment 106648

2) The throttle oscillation is very pronounced, and doesn't seem to be improving. Any other ideas?
Attachment 106649

3) Time to try "pilling" the bypass vacuum hose to calm down the valve operation...?

Attachment 106826

I'm having a similar issue. 2015 5.0 2.9 whipple 132mm throttle body.

Putting something in the vacuum line to the bypass valve help with the throttle shutting. mine is setting a driver demand reduction when it cuts the throttle.

at the 2:27 mark of the log the throttle closes

For what it's worth, I pretty much reverted to the Edelbrock tune with a slightly more aggressive driver demand table. It runs pretty well, if not a bit "soft" as boost doesn't really come in until 80% throttle. But whatever. It's more drivable.

Here's the tune for reference. Maybe it'll be a good starting point for someone else:

Attachment 107234

I worked out a rough solution for this a few months ago. I'm sure it has already been talked about elsewhere, but this is always an issue on blower swapped cars because the ECM doesn't know the actual ETC pressure ratio. Actual is SC inlet pressure/baro, but the ECM thinks its MAP/baro. Those ratios stay almost the same, until the blower bypass starts to close. Actual ETC PR is higher than expected, airflow overshoots and causes oscillation. My rough fix was to take the ETC angle error as manifold vacuum decreases and use it to adjust the throttle body model. Because technically...the extra pressure ratio that gets introduced does change effective area of the throttle. Plotting the error against Effective area and ETC vacuum and adding that 'Throttle Body Model Correction' to the original table ends up getting rid of most of the oscillation. It's a hack at its core, but it works well enough.

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Originally Posted by smokeshow

Plotting the error against Effective area and ETC vacuum and adding that 'Throttle Body Model Correction' to the original table ends up getting rid of most of the oscillation.

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Oh, lordy. I'm a newbie a this. I loosely follow what you're saying, and would like to try your solution. You're basically saying that the throttle body model needs to be adjusted so that it shows "higher flow" at higher throttle angles to reflect the draw of the supercharger. Is that right? I think Edelbrock may have been onto that, as you can see the TB model is changed in the tune file I posted above.

Would you mind providing a bit more guidance on how to accomplish that? Like, what I should log, and how to apply it to the TB model?

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Originally Posted by WesDuenkel

Oh, lordy. I'm a newbie a this. I loosely follow what you're saying, and would like to try your solution. You're basically saying that the throttle body model needs to be adjusted so that it shows "higher flow" at higher throttle angles to reflect the draw of the supercharger. Is that right? I think Edelbrock may have been onto that, as you can see the TB model is changed in the tune file I posted above.

Would you mind providing a bit more guidance on how to accomplish that? Like, what I should log, and how to apply it to the TB model?

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Yeah, basically making a fudge factor for the ETC model but calibrated based on the error you measure. Ideally the TB would be controlled based on the pressure ratio immediately upstream and downstream of it, but there's another pressure delta that gets created over the blower rotors when the bypass closes and makes the ECM's ETC area and therefore position command wrong. All I did was plot the calculated throttle angle error in the scanner graphs against table 44363 Predicted Throttle Area from the TB model and just add it. Pretty simple really.

I should also mention, you're trying to correct a feedforward error while it being quickly corrected...and air moves slowly, not to mention slow CAN data. So there may be some time discrepancy between the axes of the graph vs the position error itself. If you spend a ton of time on it and the error never converges to zero, that could be why. Don't have a good fix for that yet. I've only done this twice but it worked ok both times.

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Originally Posted by smokeshow

I worked out a rough solution for this a few months ago. I'm sure it has already been talked about elsewhere, but this is always an issue on blower swapped cars because the ECM doesn't know the actual ETC pressure ratio. Actual is SC inlet pressure/baro, but the ECM thinks its MAP/baro. Those ratios stay almost the same, until the blower bypass starts to close. Actual ETC PR is higher than expected, airflow overshoots and causes oscillation. My rough fix was to take the ETC angle error as manifold vacuum decreases and use it to adjust the throttle body model. Because technically...the extra pressure ratio that gets introduced does change effective area of the throttle. Plotting the error against Effective area and ETC vacuum and adding that 'Throttle Body Model Correction' to the original table ends up getting rid of most of the oscillation. It's a hack at its core, but it works well enough.

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This is exactly what I do with blow through throttle body setups as well (turbo/centri).

Could either of you explain this method further? I'm interested in trying it on a turbo setup. Do you recalculate both of the TB tables with the calculator? I've kinda messed with this idea (to no success) using both the calculator and my own spreadsheet that does a direct inverse of the cells. The calculator uses curve fitting, so I'm not sure if it would like me just pulling 5 degrees from an individual cell. An example histogram would be incredibly helpful!

I also managed to get ETC Vacuum into the negative, although it didn't prove particularly useful at the time, I wonder if it would help here.

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Originally Posted by RobCat030

Could either of you explain this method further? I'm interested in trying it on a turbo setup. Do you recalculate both of the TB tables with the calculator? I've kinda messed with this idea (to no success) using both the calculator and my own spreadsheet that does a direct inverse of the cells. The calculator uses curve fitting, so I'm not sure if it would like me just pulling 5 degrees from an individual cell. An example histogram would be incredibly helpful!

I also managed to get ETC Vacuum into the negative, although it didn't prove particularly useful at the time, I wonder if it would help here.

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Since I've used that max tip table that you found and populated it correctly via SCT, I don't have to do this hardly at all, as my TB model doesn't blow up in boost.

I create a histogram with the same axis as my predicted throttle angle table (Effective Area and ETC Vacuum) and plot ETC angle error. Add the error into the HPT TB calculator and be done.

You have to have a lotta confidence in your torque to load and MBT timing tables, if they're severely incorrect you'll end up eating the error into the TB model.

I'll give it a shot, thanks! That TIP table helped a great deal but it didn't resolve my issues completely. I think this is trickier on turbo setups because of the load dependency and independence from RPM. Can I ask about your wastegate setup? I'm just trying to get a 5psi spring working for now.

The area I'm trying to correct is the torque/load area where the turbo begins spooling and where it has enough load to climb to the wastegate spring pressure. So, with a 5psi spring, TIP will reach ~40inHg, and I would like the throttle to limit MAP to anywhere between 28-40inHg based on the Driver Demand. I'm finding that this .8-1.2 load area is actually pretty essential in daily street driving, so I don't want to just raise the Driver Demand until it's happy, because it feels like the car is running away from me. This is standard Ecoboost operation, but of course they have TIP sensors and an OS designed for boost.

That table does allow TIP to rise and corrects the ETC PR, but it still defaults to an ETC Vacuum of 0.3 inHg, whereas the true vacuum is closer to 5-10inHg. BTW, did anyone notice that ETC Vacuum is kind of an irrelevant variable in the ETC Model? The angles only change a fraction of a degree across the Y axis. It seems far more important to me that the correct effective area is derived from the PR function and fed to the ETC tables, which is difficult to do considering the dependence on barometric pressure. I don't see any place in the calibration to suggest that both TIP and MAP are boosted, but that boosted TIP is substantially higher than your boosted MAP.

Here's what I meant with the negative ETC Vacuum, there are some scalers in SCT that need to be modified to allow it to go negative, but it will do it once MAP>Barometric Pressure, I've logged it to be sure. I could see this maybe being helpful if you need more resolution for these types of corrections in boosted areas. But again, no satisfactory results yet. You can also do the same to the ETC PR function, but instead of negative values, you get PR values less than 1 (Baro/boosted MAP). The PCM doesn't care that you're implying flow reversal through the throttle, but desired airmass logic will bug out if you don't raise time constants.

Attachment 120518

Just tried this today and reporting back. I'm suspecting you have Desired Air Mass disabled because I found that it will shut the throttle down quickly if you don't. Not a fan of disabling this. I'm not quite sure why this is happening, but I do know that there's a scalar in SCT called "TP Pressure Ratio Filter Constant" that when raised will mitigate the issue slightly (it's also higher on Ecoboost strategies). I also know that the ETC PR Filtering will affect this, although I'm not sure exactly how and in what direction it should be moved.

With desired air mass disabled, I still get throttle correction, but I'm going to try to massage that into the ETC Model further. It's the TIP going too high as a result of the wastegate spring.

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Originally Posted by WesDuenkel

Oh, lordy. I'm a newbie a this. I loosely follow what you're saying, and would like to try your solution. You're basically saying that the throttle body model needs to be adjusted so that it shows "higher flow" at higher throttle angles to reflect the draw of the supercharger. Is that right? I think Edelbrock may have been onto that, as you can see the TB model is changed in the tune file I posted above.

Would you mind providing a bit more guidance on how to accomplish that? Like, what I should log, and how to apply it to the TB model?

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I have attached DBW from and edelbrock system. Let me know how it works out

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Originally Posted by RobCat030

Just tried this today and reporting back. I'm suspecting you have Desired Air Mass disabled because I found that it will shut the throttle down quickly if you don't. Not a fan of disabling this. I'm not quite sure why this is happening, but I do know that there's a scalar in SCT called "TP Pressure Ratio Filter Constant" that when raised will mitigate the issue slightly (it's also higher on Ecoboost strategies). I also know that the ETC PR Filtering will affect this, although I'm not sure exactly how and in what direction it should be moved.

With desired air mass disabled, I still get throttle correction, but I'm going to try to massage that into the ETC Model further. It's the TIP going too high as a result of the wastegate spring.

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I do have desired airmass disabled. It will FMEM the TB without any indication in VCM Scanner.

I'm curious as to what ecoboost strategies have as a tp pressure ratio filter constant.

I have 6 psi springs controlled through a Cortex EBC in closed loop targeting 11psi on a Copperhead.

Focus ST Ecoboost has that value as 0.200, while my car had it at 0.005 (seconds?). I raised it to 0.400 on mine, which worked when I used the MAP Delta function, but not along with the Max TIP table as well (I can use one or the other, but not both). I wonder if continuing to raise it will help.

Are you able to hit load areas below the wastegate pressure the way I'm describing? In other words, could you steady state without throttle correction at say 3psi MAP?

There's surprisingly little discussion on what the Desired Air Mass switch does, which is kind of frustrating seeing how critical it can be.

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Originally Posted by RobCat030

Focus ST Ecoboost has that value as 0.200, while my car had it at 0.005 (seconds?). I raised it to 0.400 on mine, which worked when I used the MAP Delta function, but not along with the Max TIP table as well (I can use one or the other, but not both). I wonder if continuing to raise it will help.

Are you able to hit load areas below the wastegate pressure the way I'm describing? In other words, could you steady state without throttle correction at say 3psi MAP?

There's surprisingly little discussion on what the Desired Air Mass switch does, which is kind of frustrating seeing how critical it can be.

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Copperhead has it set to .2 from the factory cal.

I can without a problem. I either have to populate the TIP max table, hack the ETC PR table, or remap the TB with huge values. Since populating TIP max, I prefer that method rather than hacking the TB model. I now only have to make very small changes, mostly in high ETC vacuum areas, to almost completely eliminate any ETC error.

I used to think that without a TIP sensor, the TIP max table would be useless, but that definitely is not the case. The PCM does seem to be able to infer TIP when MAP>BARO.

The desired air mass logic seems to be used to determine a desired intake manifold pressure, which will then calculate a target TB angle (it's actually way more complex but this is the part I feel applies to the issue). Under certain circumstances, mainly low rpm-high map pressure, it will cause TB FMEM of some type that doesn't report in VCM Scanner. I suspect there are pressure clips that we don't have defined. Having a power adder on a factory NA strat throws this logic out the window and just causes more issues than it's worth.

Okay, I think I've made some progress (and apologies that I've derailed the OP, if this works out, I'll make a new thread to explain better). Based on what you're saying, my TC1767 isn't quite the same as your Copperhead. Making some drastic changes to my ETC model, I was able to work out the first 50% of my pedal/DD without torque errors. For calculating the effective area table, I made this spreadsheet to calculate a linear inverse, cell-by-cell. I don't think you can use regressions/curve fitting (what the HP calculator uses) in this instance because the R-squared value of the new data is relatively low. Plus I have no desire to recalculate an area of the table that I know to be accurate (ie. no boost)

Attachment 120682

Fun fact, at least this is new knowledge to me: even at WOT the throttle angle cannot exceed the Predicted Angle table. So while the first 50% of my accelerator works flawlessly, the remaining 50% refuses to exceed a throttle angle of 30ish degrees despite the higher ETC request (since it thinks it has enough effective area to flow what I'm asking).

Second fun fact. I traced ETC Requests at different RPM to see where they were pulling from the Predicted Angle table. Turns out there is an excessive amount of overlap, particularly along the 0.3inHg ETC Vacuum row. Here's why. The Max TIP table lets the TIP rise with desired MAP (and desired MAP is still the main driver for throttle control, even with the switch disabled), but it doesn't know exactly how much higher. In my instance, I have a 10psi wastegate spring, so while I'm commanding a desired MAP of say 35inHg, the calculated TIP might be 35.3inHg, while my actual TIP is closer to 50inHg. Actual ETC Vacuum is 15inHg while the calculated vacuum is stuck at 0.3inHg. More importantly, my calculated ETC PR is 1 while my actual PR is 1.42, which would drastically affect the effective area calculation. So, it's still closer than the massive effective area values I would see if I hadn't used the Max TIP table, but it still isn't completely accurate.

How to fix? The best I can come up with is using negative ETC vacuum, which I will test soon hopefully. This is not the way Ford intended to use the table (predicted angles were meant to increase horizontally, not vertically), but hey, they gave us a Y-axis, why not use it. This way I can use deeply negative ETC vacuums to specify that I want the throttle to open fully at maximum boost. The only other important thing is that having a jerky Predicted Area table will produce to very similar results to having a jerky MAF curve. So, I also think it's still important to check your R-Squared values both horizontally (quadratic) and vertically (linear) if you use this.

Any feedback on all this would be appreciated as I feel kinda off the deep end here. I'm just tried of the crappy drivability with my car, if this doesn't work I will probably start swapping the Ecoboost electronics.