2006 Jeep 4.0 Part Throttle vs WOT Spark strategy and TPS voltage

[Johan6504]

Hi,

I'm trying to better understand the spark/WOT strategy in the NGC3 PCM on my 2006 Jeep Wrangler TJ 4.0L / 42RLE.

In VCM Editor I have two separate base spark tables:

Part Throttle Spark
WOT Spark

Both are indexed by RPM and MAP, but I haven't been able to determine exactly what causes the PCM to switch from Part Throttle Spark to WOT Spark.

I have a ~33 minute stock VCM Scanner log with several high-load/WOT events. When I compare the logged Timing Advance and Total Spark Correction against the two calibration tables at the corresponding RPM/MAP, the engine appears to follow the Part Throttle Spark table even around 95?98 kPa MAP and with the accelerator on the floor.

So my first question is

How does the 2005?2006 Jeep 4.0 NGC3 actually select between Part Throttle Spark and WOT Spark?

Is WOT Spark a true alternate base table selected by a WOT operating mode, is there some blending/modifier strategy involved, or are there additional conditions that must be met before the WOT Spark table is used?

I have a second issue which may or may not be related.

Under Fuel → Power Enrich, the stock calibration has:

WOT Pedal Threshold = 3.7843 V
WOT Pedal Hysteresis = 0.0980 V

However, VCM Scanner only shows a maximum TPS of approximately 3.04 V with the accelerator fully on the floor.

I have checked this with two different physical TPS sensors and get essentially the same result. Closed throttle is around 0.3 V and maximum is roughly 3.0?3.1 V.

Despite never reaching the displayed 3.7843 V threshold in Scanner, the PCM clearly does enter enrichment. The calibration also has FA WOT Delay = 8.480 s, and during one sustained high-load event the Desired FA Ratio remains around stoich initially and then moves into enrichment after roughly that delay.

So my second question is:

Is the TPS voltage shown by VCM Scanner using a different scaling/reference from the WOT Pedal Threshold shown in VCM Editor, or is the PCM using another internal pedal/TPS value for the WOT determination?

I'm not looking to change the thresholds or spark tables yet. I'm trying to understand the stock NGC3 strategy before making any calibration changes, and eventually before tuning a naturally aspirated 4.75L stroker.

If useful, I can post the stock .hpt file and the raw VCM Scanner log.

Thanks,
Johan