GM > Engine > Fuel Control > Power Enrich

Power Enrich Fuel
Power enrichment tables are used when the VCM detects wide open throttle (WOT) operation and provides extra enrichment to achieve maximum power.

Note: A working, calibrated and correctly positioned wideband O2 sensor is required to tune engine fuel requirements. Excessive lean conditions due to incorrect use of these parameters could lead to severe engine damage.

PE Enable

• Enable MAP: This MAP value must be exceeded to enable PE mode
• Enable MAP Hysteresis: This value is subtracted from the enable MAP value. If the MAP reading drops below this value then PE mode will be disabled.
• Delay RPM: PE mode is delayed if RPM is below this value. Set to 0 to disable PE Delay and enter PE mode immediately.
• Enable RPM: This RPM value must be exceeded to enable PE mode
• RPM Hyst: If enabled, RPM value must drop by this amount to disable PE mode
• Enable Torque %: Percent desired torque required to enable Power Enrichment
• Torque % Hysteresis: Percent desired torque hysteresis for disabling Power Enrichment

PE Enable TPS vs. RPM

• Hot Power Enrich Enable %TPS Threshold vs. RPM: These tables defines the minimum TPS% vs RPM that the VCM requires to enter WOT and is required to enable PE mode. There are two tables labeled Hot and Cold that allows different thresholds depending on whether the coolant temperature has exceeded the Hot Select temperature (see below). If the coolant temperature exceeds the Hot Select temperature then the Hot table is used, otherwise the Cold table is used (not available on all PCMs).
• Cold Power Enrich Enable %TPS Threshold vs. RPM: These tables defines the minimum TPS% vs RPM that the VCM requires to enter WOT and is required to enable PE mode. There are two tables labeled Hot and Cold that allows different thresholds depending on whether the coolant temperature has exceeded the Hot Select temperature (see below). If the coolant temperature exceeds the Hot Select temperature then the Hot table is used, otherwise the Cold table is used.
• Hot Select Temp: This value selects either the Hot or Cold TPS threshold table (see above).

• TPS vs. RPM: This table defines the minimum TPS that the VCM requires to enter WOT and is required to enable PE mode.

Power Enrichment

• V8 Power Enrich Fuel EQ Ratio vs. RPM: This is the main table that is used to tune WOT fuel for post 1999 V8 engines. The values in this table are Equivalence Ratio's (Fuel/Air multipliers or AFR divisors) ie. values greater than one are richer, values less than one are leaner. The values relate directly to the Stoich AFR and the resulting commanded AFR is Stoich divided by this PE equivalence ratio. Eg. if the multiplier is 1.1 then the commanded AFR will be 14.7/1.1 or 13.36.
• V8 Power Enrich Fuel EQ Ratio vs. RPM(Alcohol): This is the main table that is used to tune WOT fuel for post 1999 V8 engines. The values in this table are Equivalence Ratio's (Fuel/Air multipliers or AFR divisors) ie. values greater than one are richer, values less than one are leaner. The values relate directly to the Stoich AFR and the resulting commanded AFR is Stoich divided by this PE equivalence ratio. Eg. if the multiplier is 1.1 then the commanded AFR will be 14.7/1.1 or 13.36.
• Power Enrich Fuel Adder vs. Coolant Temp: This table adds to the PE multiplier (above) in relation to engine coolant temperature (ECT).
• Power Enrich Fuel Adder vs. Intake Air Temp: This table adds to the PE multiplier (above) in relation to inlet air temperature (IAT).

• V6 Power Enrich Base vs. ECT: This table sets the base AFR for Power Enrichment on V6 engines. Note this is an AFR value, higher is leaner.
• Power Enrich Fuel Adder vs. Throttle Position Sensor: This table adds to the base AFR in relation to throttle position. It is generally used to lean the fuel at smaller throttle settings.
• Power Enrich Fuel Adder vs. RPM vs. Time: This table adds to the base AFR in relation to RPM and time in PE mode. It is used to provide additional RPM and time based enrichment and is similar to the PE vs RPM table on V8 engines, but with an additional time component. Remember, this value adds to the Base PE AFR so positive numbers here are leaner and negative numbers are richer.

• Enrichment Rate: This is the rate at which Fuel is added to reach the desired enrichment value. The smaller this value is, the slower the VCM will reach the desired PE AFR. For instance if your non pe commanded EQ ratio is 1.0 and your pe commanded EQ ratio is 1.300 and your enrichment rate is set to .3 it would take 1 step ~10ms for most pcms to reach full PE.

• Base AFR vs. ECT: This table sets the base AFR for Power Enrichment on some I4/5/6 engines. Note this is an AFR value, higher is leaner.
• Base AFR Mult vs. RPM: This table multiplies the base AFR for Power Enrichment on some I4/5/6 engines in relation to RPM. Numbers less than one will lower the AFR (richer), numbers greater than one will raise the AFR (leaner).

Boost Enrich
These values are for 2bar or 3bar Speed Density packages.

• Boost Enrich: This table is an Equivalence Ratio (just like the PE table) and referenced to MAP. The PCM will use the richer of this table and the PE table to determine fueling. It is useful for some supercharged and turbocharged engines where boost does not always correlate to RPM.
• Enable MAP: This is the minimum MAP to enable the Boost Enrich table. Additionally, above this MAP the engine will enter open loop.
• MAP Hysteresis: This is the MAP hysteresis to disable the Boost Enrich table.

Piston Protection

• Enable RPM: RPM must be above this to enable Piston Protection (fuel enrichment) mode. Set to maximum to disable.