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Besides this document, an additional resource for ECU logic details are the table descriptions shown in the Accesstuner software. These will show up in the lower left corner of the software for the current table that is selected. If not visible, make sure the "Table Description" check box is selected in the View menu. Additionally, the Help menu in the software contains links to documents that list all of these table descriptions as well as all of the data monitor descriptions.

CONTACT US

COBB authorized Protuner Authorized Protuners are welcome to contact us with any additional questions/concerns or when in need of troubleshooting assistance.

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  • Requested Torque tables are split by the estimated gear position (1st through 6th). A new Gear Position ESTIMATED Req Torque monitor tracks the unique gear position monitor used for table switching.

  • When transitioning between gears, the Requested Torque (Gear Transition) table is used.

  • Due to hard-coded limits, the maximum Requested Torque value is capped at ~350 n-m.

TUNING STRATEGIES

MISCELLANEOUS

LIGHT LOAD KNOCK

During testing, we observed that certain 2022 WRX vehicles can demonstrate very significant knock corrections under very “light duty” conditions. This typically occurs when:

  • The driver reduces throttle input after an acceleration event, but does not lift off of the accelerator entirely, such as when reaching desired speed after leaving a stop light or entering the freeway

  • Engine Speed is between 2000 and 3000 RPM

  • Calculated Load is below 0.5 g/rev

When this behavior begins:

  • FBKC will rapidly increment negative into large absolute values

  • It will often continue until the driver inputs change, such as increasing or decreasing accelerator position, or until the FBKC value reaches its maximum negative value allowed by the calibration

  • It will generally demonstrate itself as large spikes specifically in the “Knock Sensor Noise Level Cylinder 3” monitor

  • These spikes can be reconciled against the “Knock Sensor Level Threshold Cylinder 3” monitor

  • Any time that the Noise Level exceeds the Threshold, an FBKC increment will occur

Our testing indicated that:

  • The behavior is not consistent across cars but will be easily observed on the stock (or Stage0) calibration for those cars that are impacted

  • This issue is not specifically worsened or alleviated by changes in octane; it was observed on 91 octane up to 96 octane fuel

  • It is unlikely that the noise is being generated by legitimate knock events and that it is mechanical/external noise (or another anomaly)

  • Many FA24 vehicles, including Ascent, also exhibit the noise spikes on Cylinder 3, but often to a reduced maximum, effectively reducing or entirely negating the severity of the issue

Potential consideration for further investigation:

  • The VB WRX 6MT features a mechanical vacuum pump for the braking system and brake booster, as does the Ascent

  • This vacuum pump is attached to the passenger side cylinder head and the back of the intake camshaft “behind” Cylinder 3, which could potentially contribute to the excessive noise being detected on that cylinder

  • The VB WRX CVT does not utilize this hardware and instead uses an electric brake booster configuration; the cylinder head is fitted with a blanking plate at the factory for this configuration

  • We were unable to reach a specific conclusion on if this component may play a factor in the issue

Our Stage1 maps have a series of small changes included that help mitigate the frequency of these light load knock events, though larger changes may be needed depending on the vehicle and the specific behaviors observed.

IMAGE: Visual representation of the issue occurring on an in-house test vehicle during early R&D efforts. This is on the stock calibration and a vehicle running 92 octane located in Portland, OR. The 3rd graph shows the noise spikes exceeding the threshold, the 2nd graph shows FBKC incrementing downwards when those spikes occur, and the 1st graph shows the benign conditions under which it is occurring (Load below 0.5 g/rev, APP below 15%, etc.). While not shown in this graph, Cylinders 1, 2 and 4 do not demonstrate the noise spikes at all during this event.

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