Tag Archives: ATS-V

Cadillac ATS-V Driver Demand & Torque – Tune E

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Hp Tuners view of Hp, Torque, boost, TCC slip, and Throttle at RPM

The above chart is based on a layout file for HP Tuners to help with analysis.

The red line is HP, the light blue line is Torque, across two gears, 2 & 3, from 17 to 78 mph.

The dark blue line is throttle (versus pedal input), or how much the PCM commanded the throttle. The white line is RPM.

The yellow line is boost. There is a strong correlation between the boost curve and the Torque or HP curves before/after 5252 RPM where they cross by definition. Boost holds at 17.49 psi in second, and rises to 19.47 psi in 3rd gear.

At the highlighted snapshot moment, driver demand is at 109%. After this, driver deman falls off; I am not sure why. Later in the run at 5696 rpm in 3rd gear the commanded throttle opens due to boost pressure limits being exceeded, and boost falls off after that point, crushing the HP curve from there. Those boost limits will need further attention in the next tune.

The gold line is TCC Slip RPM. I note that here in my tune E TCC slip is actually well controlled in 3rd gear, and falls across 2nd gear rev range. I plan to increase the TCC pressures across 2nd gear parameters.

Overall this layout was helpful in analyzing individual tests, and comparing across scan files for these parameters.

Cadillac ATS-V LF4 Tune E1

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Purpose: Keep the throttle closed again after boost ramp up. Eliminate TCC slip. Study KR vs PE by going richer, so closer to tune c2.

Plan: Raise PE to 12.7 to try to address KR; no change to spark map for this run. Address TUTD shift RPM to try to enable automatic shift up in 1/2/3/4 not 5/6/7/8 so can hold those if needed for dyno. Adjust Turbo Knock Mass to raise desired boost level to try to close throttle. Study scanner with car to understand missing channels. Modify TCC pressure apply ramp to reduce TCC slip. Rescan.

Conditions: 76F, 29.83 baro, 87% humidity. SAE J1349 correction 1.0052575076413.

Data:
2nd gear 456.8 hp @ 5838 rpm / 458 torque @ 5126 RPM with 17.4 psi boost at peak hp
3rd gear 464.8 hp at 5320 rpm / 469.5 torque @ 4660 RPM; with 19.4 psi boost at peak hp
Corrected 3 gear: 467.2 hp / 471.9 lb-ft torque

Result: Still getting KR at WOT at 12.7:1 PE and current spark map.
Throttle opened at 5718 RPM in at 71 mph on one test, stayed closed in another. Desired boost just before 34.5, actual boost 34.4 psi. Then desired boost falls off and throttle opens. 2.3 degrees KR showing at that point. MAT 133F. Boost 19.1 psi. Cyl airmass 1.34. fine on boost max limit but pinched on knock airmass. So further knock airmass adjust?

Comparative results from last 3 scans on TCC slip error; still needs attention. For the gallery images, right-click then select view in new tab to see full page versions.

Test C2
Test D1
Test E1

Missing parameters: Connected to vehicle, then repolled vehicle for parameters. Now everything is showing again. I think this happened after I changed from stable release to beta release, but beta release is seeing all the parameters after repolling.

Cadillac ATS-V Tune D2 Notes

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Areas addressed: (1) Set AFR to 12.25 (2) spark advanced reduced 1-2 pts at WOT range of 1.16..1.32 4500-6500 to address KR (3) Boost max limit up 0.4 to allow more boost; (4) Pressure delta up 0.05 to build boost faster (5) boost knock airmass max 1.34 to allow more desired boost (6) TUTD set to autoshift 1/2/3/4 (speed) (7) airflow turbo base DC added 5 to 1.6/2500->3/6750 to allow a higher waste gate duty cycle (WGDC).

Current Conditions Settings Mostly Cloudy 86°F Feels Like: 89°F Humidity: 63% Wind: SSE 17 mph Barometer: 29.88 in Dew Point: 71°F. SAE  Air Correction Factor =   1.0176355313799041 J1349 AUG2004. Max 451.8 hp equates to 459.8 SAE J1349 hp. I remembered to test with a/c off, and in track mode. Hotter day than prior, at 87F vs 60F, hot car.

Thoughts: We are making more boost, but throttle is closing again. Absolute Boost 33 exceeded desired 32.7 as RPM climbed through 5157 RPM at 63 mph causing throttle to close even though pedal at 100%. Boost math exceeded 17.8 psi at that point; boost/vacuum 18.7 psi. Cylinder airmass 1.27 g, KR 1.1 degrees.

Boost math to 17 psi max in 1st gear, 18.1 psi in 2nd gear, 17.8 psi but then throttle closed in third gear. So good news we are seeing higher boost in lower gears. But more headroom needed in desired boost. Planning to add headroom in knock airmass table, or in max boost table; the manifold air temp broke over 160F on that run, which is where max boost is limited to 33.2 psi. Overall another run with the same tune but cooler air would be interesting.

Still some KR in the 1.16 to 1.32 pressure ratio, 4000 to 6000 rpm, even after I removed 2 degrees of spark here; although it responded to initial removal of 1/2 of the spark it didn’t respond to removal of the other 1/2. I changed the AFR at the same time, however. It may prefer less lean?

The transmission adjustment I made to add automatic shift to tap up / tap down (TUTD) mode was not successful. I changed TUTD vs speed but not vs RPM, which is set to 7K. I will add RPM limits to match pattern A or B for tune E.

Boost solenoid DC: I added 5% duty cycle from 1.16 to 1.32 pressure ratio, 2500 to 6750 in an attempt to get more boost earlier. The duty cycle hits 60% in 1st and 2nd and close in 3rd before the throttle opens. Appears to be working as intended but helped exacerbate the throttle closing.

Scanner note — switched to latest beta 4.11.1374. Several channels previously scanned successfully disappeared for some reason; not clear why.

Next steps: Raise PE to 12.7. Address TUTD shift RPM. Adjust Turbo Knock Mass to raise desired boost. No change to spark map. Re-initialize scanner with car to understand missing channels. Modify TCC pressure apply ramp to reduce TCC slip. Rescan.