Coyote with VMP - light throttle surge??

[kjlindgr]

Hey all, I have an SN95 application here that's got a Coyote swap in it with a VMP supercharger (Loki kit). The engine is controlled with a FRPP kit and harness. Setup has a stock Coyote throttle body on it. The car idles fine, and WOT is good, but low throttle (20-25%) the car surges like crazy. I'm not a very good Coyote tuner so I'm really not sure where to go from here or how to resolve it.

Below you can see the surging. The APP is held pretty constant, but the throttle body is swinging, and the car is going in/out of boost. I'm not sure what the cause is and what the effect is. I tried playing around with the DD tables to keep the throttle more consistent but I think I'm chasing my tail a bit...and this may not even be where I need to focus my attention.

I'm hoping someone can point me in a good direction!

surge.png

Tune file:
TUNE_dd_adjust_0006.hpt

Log file:
tune_x_surge.hpl

[mstang_man]

Hey all, I have an SN95 application here that's got a Coyote swap in it with a VMP supercharger (Loki kit). The engine is controlled with a FRPP kit and harness. Setup has a stock Coyote throttle body on it. The car idles fine, and WOT is good, but low throttle (20-25%) the car surges like crazy. I'm not a very good Coyote tuner so I'm really not sure where to go from here or how to resolve it.

Below you can see the surging. The APP is held pretty constant, but the throttle body is swinging, and the car is going in/out of boost. I'm not sure what the cause is and what the effect is. I tried playing around with the DD tables to keep the throttle more consistent but I think I'm chasing my tail a bit...and this may not even be where I need to focus my attention.

I'm hoping someone can point me in a good direction!

surge.png

Tune file:
TUNE_dd_adjust_0006.hpt

Log file:
tune_x_surge.hpl

I would work on the Maf transfer function it needs attention, once thats fixed if still have issues look towards torque and torque inverse.

[kjlindgr]

When you say MAF transfer function, are you referring to the "MAF airflow vs period" table?

[Screamin'04]

When you say MAF transfer function, are you referring to the "MAF airflow vs period" table?

Yes... Make sure your injector data is right and then get that MAF transfer table right before you do anything else.

Here are some links that helped me the most when I did mine.

Calculate MAF/CAI Area:
https://forum.hptuners.com/showthrea...l=1#post420417
https://forum.hptuners.com/showthrea...l=1#post401879

MAF Transfers: http://www.efidynotuning.com/maf.htm
Injector Data: http://www.efidynotuning.com/injdata.htm

Once you get everything roughed in and the car running "OK", disable LTFTs and use this Histogram ... You want everything as close to 0 as possible.

MAF Period STFT.Table.xml

A negative number means it's pulling fuel, a positive is adding fuel. I'm generally happy within 3% to 5%... (although, I'm far from a professional tuner).

Screenshot 2022-06-23 145017.png

[kjlindgr]

Dumb question - I understand you want your fuel trims as close to zero as possible, but how does this impact the torque delivery and surging issues I was seeing?

[Screamin'04]

Dumb question - I understand you want your fuel trims as close to zero as possible, but how does this impact the torque delivery and surging issues I was seeing?

The ECU will attempt to compensate elsewhere for bad MAF data and cause problems.

[Screamin'04]

Hey all, I have an SN95 application here that's got a Coyote swap in it with a VMP supercharger (Loki kit). The engine is controlled with a FRPP kit and harness. Setup has a stock Coyote throttle body on it. The car idles fine, and WOT is good, but low throttle (20-25%) the car surges like crazy. I'm not a very good Coyote tuner so I'm really not sure where to go from here or how to resolve it.

Below you can see the surging. The APP is held pretty constant, but the throttle body is swinging, and the car is going in/out of boost. I'm not sure what the cause is and what the effect is. I tried playing around with the DD tables to keep the throttle more consistent but I think I'm chasing my tail a bit...and this may not even be where I need to focus my attention.

I'm hoping someone can point me in a good direction!

surge.png

Tune file:
TUNE_dd_adjust_0006.hpt

Log file:
tune_x_surge.hpl

I found that having nice, smooth torque tables really cut down on interpolation between cells and smoothed out the vast majority of my surging issues.

As a final tweak, I dialed in my ETC with ETC Predictive angles.

Between the two (after MAF tuning), I have no more surging issues. Car drives like a stocker with a Gen3R, locked out VCT, lopey Cams, 163R throttle body and 148mm CAI.

Screenshot 2022-06-23 150532.png

Here's my notes on the ETC Predictive... In my experience, adjusting the torque tables has an affect on the ETC angles... So any time I adjust my torque tables, I do a slight amount of error correction on my ETC angles. Although (again), I'm far from a professional tuner.

Effective Error Histogram

If you only have 1 error in a column, such as column 0.022, where the error is -.11.
The correction would be -.11/2=-.055, so you would add -.055(which is really subtracting) to the entire column.
If you have more than 1 error in a column like .177, you would average the values and then divide by 2.

.32+.17+.22+-.11=.6
.6/4=.15 (average)
.15/2=0.075 (correction factor)

So you would add 0.075 to the entire column under .177

Also, remember you have to change the ETC Effective Area Table when you make changes to the ETC Predicted Throttle Angle table.

You will update Effective Area X axis with the top row of Predicted TA.

Then, use the HP Tuners "ETC Effective Area Calculator" to update your Effective Area

https://forum.hptuners.com/showthrea...l=1#post416554

Effective Error.Table.xml

Here are two spreadsheets that I made to help me with both the above.

2022-06-23_15-17-23.png2022-06-23_15-38-09.png


This is an Excel macro-enabled workbook (meaning it has VBA code embedded) for clicking the "Calculate" button in the ETC sheet.

Because you cannot upload .xlsm files here, and only .xlsx files, you'll need to drop the .xlsx off the tail end of the filename on your side.

"MAF & ETC Area Correction.xlsm.xlsx" becomes "MAF & ETC Area Correction.xlsm"

Attachment 121594

Lastly, feel free to open the VBA editor in Excel to examine the code before you click anything if that makes you feel more comfortable. (Alt + F11 in Windows)

Screenshot 2022-06-23 161724.png

Make sure to normalize ALL axis values in the VCM Editor Tables and VCM Scanner Histogram/Graphs and any other reference materials (spreadsheets).... This really helped me quite a bit too... If the axis values are not all matching, then what you "think" you're adjusting may not be having the intended effect.

[kjlindgr]

Thanks for the info and resources. Other questions -
1. how did you dial in your torque tables?
2. My predicted ETC has more columns than on your sheet. Not being an excel guru, is there a quick-n-dirty way to expand this to work for my application?

Thanks again for the help

[Screamin'04]

Thanks for the info and resources.

You're quite welcome... Apologies for the delay in responding. This is all stuff I just sorta "figured out". So, it has taken some time to put it all together here.

Other questions -
1. how did you dial in your torque tables?

So, the torque tables themselves are relatively complicated... The way I did it "may or may not be" the correct way...

Again, I'm no professional tuner. BUT, this did work VERY well for me... I had MAJOR drivability problems with my professional tune... The instant you went past 0 inches of vacuum, the Gen3R would throw 25psi down. There was absolutely horrid transition with hucklebucking, spitting, popping, stalling, etc... Combined with the locked out Comp Cams stage 3 cams, I'm only working with like ~8 inches of vacuum at idle to begin with. So, I could barely merge into traffic or start off from a stoplight without problems. And this was AFTER I trailered the car 1,900 miles round trip for my tuner to have on-site on their Dyno... The car now drives like 99% as good as it did when it was stock.

Note: Any histograms in VCM Scanner must have all respective channels added to the scanner. Your specific strategy may not have the same channels available as mine, so you may need to tailor the histograms to suit what channels you have available in your strategy.
Tip: In VCM Editor, use "Vertical Split" view to use 3D Charts in parallel with the 2D tables. You can zoom in/out on the 3D chart by holding both mouse buttons. This greatly eases the table smoothing process.

----

You must have your MAF and fuel trims as close to correct as possible first...

To start, you'll want to normalize the "Engine Load" column of your Torque Tables (and respective spreadsheets) based off of however much boost you'll be targeting... As a matter of fact, you'll want to make sure that ANY table you touch in your tune is normalized based on your specific combination and intended use... I use 1.6 for Engine Load as I see ~25psi with my 63mm / 20% pulley combo. I could probably take it up to 1.8, but haven't bothered yet.

Then, go to [ECM] 38155 - Mapped Points Configuration and disable everything except "Mapped Point OP". A "0" will disable, a "1" will enable. Note what is enabled versus disabled for re-enable use later.

Also, you'll want to set [ECM] 44385 - IPC Wheel Torque Error Max to some ludacrisly high number... I used 500,000.00. The ECU will go into limp mode if your IPC errors pass this max threshold.

Starting with the OE table, I made rough adjustments based on the torque from my dyno sheet (accounting for parasitic loss).

Then, drive around at varying speeds and load, while using the attached MPOP histogram, using the histogram, I further customized the table.

Then, I worked again with my previous dyno graphs again to further tweak the table (again). Once close, I worked on smoothing everything out as good as possible.
Screenshot 2022-06-23 150532.png

Next, I used the OP_MP Table Comparison spreadsheet (attached) to replicate the OE table deltas to my Optimized MP Table to all my other torque (MPx) tables. Once complete, I used the built-in VCM Editor Torque Inverse Calculator to recalculate all of my inverse tables.

I then go back to [ECM] 38155 - Mapped Points Configuration and enable my torque tables one at a time, drive around at varying speeds and load, while using the respective MPx histograms to refine each table. I only did this for the tables that were enabled originally.

I then used the IPC Torque Min_Max spreadsheet (attached) to refactor my IPC Wheel Error Min/Max tables. Right now, I'm using a 3.25% error margin. Try to keep this as tight as possible. But you can hone in on it as you go... IIRC, I started at a 10% error margin.

Next, I use this Driver Demand histogram and my personal driving preferences to customize my Driver Demand table(s). I have a 6R80 car, so I do this for both normal and sport mode driving. Your strategy is completely different than mine, so I won't go into detail on this. But it's essentially the same as the others IMO. Work with everything until your satisfied with how the vehicle drives.

I then go back over my ETC Predicted Throttle Angle a few times to get the Throttle Body corrected based on the new tables. I do this until I get my ETC Errors less than +/- 1 degree. The smaller the error, the better the throttle body will feel. When you're right on the money, you should be able to hold the pedal at like 2,000, 2,500, 3,000 (or any) RPM without any engine speed fluctuation.

Finally, I go back over my MAF Period / Fuel trims again one last time.

Ideally, everything will run correctly and IPC Wheel Torque errors will be as close to 0 as humanly possible. (without fudging the min/max thresholds).

Once everything is said and done, you can put [ECM] 44385 and [ECM] 38155 back to what they were originally.

If you're like me, this process will take several weeks (without a dyno) of driving, logging and revisions to get it nailed. I saw probably 70% better drivability though, after only 3 days (which was long before I started using this method).

There's probably more that I'm forgetting at the moment... But you should be able to figure something out based on this AND other reference posts here on the forum.

Ref:
https://forum.hptuners.com/showthrea...l=1#post467731
https://forum.hptuners.com/showthrea...l=1#post420228
https://forum.hptuners.com/showthrea...l=1#post534582
https://forum.hptuners.com/showthrea...l=1#post534694

Other questions -
2. My predicted ETC has more columns than on your sheet. Not being an excel guru, is there a quick-n-dirty way to expand this to work for my application?

I've updated the ETC Predicted Area sheet per the tune you attached to your original post.

Don't' forget to rename HP Tuners Coyote Worksheets.xlsm.xlsx to HP Tuners Coyote Worksheets.xlsm

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Thanks to the other forum members and posts here for giving me enough information to be dangerous; but also enough information to get my personal vehicle to a "happy place"...

The attached spreadsheets are something that I built along the way to help simplify my own tuning experience. While they are based off of calculations found here on the forum, I cannot/do not warranty that they are 100% perfect... So use them with caution and apply your own due diligence in your tuning so as to exercise the appropriate level of caution.