Graphing HP Tuner Data

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Although the HP Tuners scanner does a terrific job of showing both numeric and graphic data, it is helpful to compare results from different scans outside the tool.

The scanner allows export of the scan data in .csv, or comma delimited text format. This data file can then be imported to Microsoft Excel, and graphed. In this case, I exported from two different scan files, then added each as a worksheet within a single Excel workbook, added a calculated field, then graphed the two data sets together as x/y scatter graphs. It is helpful to use the ‘export visual’ option within HP Tuners to limit the data exported to the single WOT run in each case, or close to it.

HP Tuners did not export the calculated horsepower. I added a column to the data calculating HP = Torque x 5252 / RPM.

The chart above shows (blue and green) my current tune 3c2 scan for a single WOT run versus the stock tune on a different day single WOT run. This type comparison is inexact due to differences in variables (day, weather conditions, road used) but is helpful as a way to measure overall impact and to look for problem areas.

The data is uncorrected, and unsmoothed. Often dyno results will be corrected to STD or to SAE 1349, which help to match weather conditions. Smoothing also helps eliminate single peak max values. In this case the weather conditions were similar, and we are looking for trend comparison not peak comparison, but would be possible to make the same corrections and smoothing on the data within the data table prior to graphing.

The Blue torque after line compares to the red torque before line, and the green hp after line compares to the orange hp before line.

As expected, what I conclude is that the current tune is better across the board as compared with the stock tune

ATS-V LF4 HPTuners Tune 3c2

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Current Scan snapshot:

Prior scan snap shot at same rpm/speed showing throttle closing then:

First test for my ATS-V LF4 with tune 3c2. My intent is to change the least number of parameters in order to allow the engine to make as much power as it can. My goal is a stable 18 psi tune with no KR and no throttle closing.

Current conditions were 68F, 12 mph wind, 92% humidity, 29.81 in Hg pressure. SAE correction factor 0.9923039631981221, so 467 hp equates to 463 SAE 1349 HP.

There was some Knock Retard (KR) at cylinder pressures 1.16-1.32 during full throttle operation. I used a table to analyze where I was getting KR by RPM and pressure, then reduced the spark commanded in this region by 1 point in the effected areas. A rule of thumb is reduce the spark 1/2 of the KR observed. In my case this appears to have reduced the KR but not totally, so I will need more attention here.

Torque Management – General – max engine torque limit – I multiplied the 0% and 20% alcohol rows by 1.2, for a 20% increase.

Torque Management – General – TCS max torque set from 445 lb ft to 550 lb ft.

Torque Management – Driver demand – tables A and C I multiplied the bottom row by 1.1, then the bottom 2 rows by 1.1, then the bottom 3 rows by 1.1. This applied a stacking increase the the bottom 3 rows.

Torque Management – S/C Boost control – max limit I added 2 psi across from the left up through manifold temp 158, leaving higher temps unchanged. This added 2 psi to ceiling when the manifold temperatures are in check.

Good news: Holding throttle. the first image shows throttle is matching the pedal input. Also, boost (math) around 18.x psi total; here, 17.8 psi versus 14.9 psi prior, so 2.9 psi increase.

To do list: Still some KR to clean up with reduced spark. I also still see hints of desired falling in ranges I am unsure why it is not holding stable, so more study needed.

I am making progress toward my goals; I see 18.4 psi of boost, and no throttle closing. More tuning needed for KR.

Cadillac ATS-V HPTuners Stock Scan & Throttle closing

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I am starting to run driving scans on my 2016 ATS-V to get a feel for how the engine operates. The LF4 twin turbo 3.6L engines use a torque management based strategy. The control sorts out what torque is desired, then manages the powertrain to make that torque, independent of throttle input. The throttle input (gas pedal) is treated as a request — so you might have the pedal on the floor, but if the engine is making over 100% of the torque planned at that moment, the actual throttle may close to maintain the torque to the planned levels.

In the image above, the Cadillac is accelerating through 61 mph, at 5313 RPM. The pedal is at 100%. The actual throttle however, is at 67.8%. The ATS-V was making “too much” power at that moment. If you examine the 2nd row in chart vs time, the green line is throttle %, so where we see dips in the green vs yellow line is where the ATS-V is reducing engine power to desired or planned output.

In this case, at this point, the total boost pressure of 31.5 psi (without adjusting for baro) was higher than the Desired Boost pressure of 30.7 psi. So the engine controller is pulling back the throttle because too much power is being made.

I also note that the stock file is running a few points of KR, or knock retard. There is a ramp up of the planned advance in that range. The engine controller goes from a spark advance of 8 degrees up to 10.5 then down to 10 degrees. That appears to be too much since the KR (knock retard) is going to 2-3 degrees there. Although it is possible that a richer air fuel ratio (AFR) would be fine.

The ‘stock’ commanded AFR is 12.8, lamda 0.909 equivalence ratio commanded. This is within the range of what most tuners are doing with the LF4 direct injected V6. This ATS-V may prefer to be slightly richer, but needs more research.

Correction Factor: Ambient air: 72F, Intake air 75F. Baro 29.5223 inHg, 83.13% humidity so SAE J1349 correction of 1.01555. 453.6 hp corrects to 460.7 hp.