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Air/Fuel Ratio: Here Show Toolbars

The document discusses air/fuel ratios and provides information on: - Different modes the PCM can enter that affect air/fuel ratios such as MAF closed loop and Speed Density open loop. - Units of measure for air/fuel ratios including stoichiometric, lambda, and EQ ratio and how to convert between them. - Typical stoichiometric air/fuel ratios for common fuels like gasoline, natural gas, propane, ethanol, hydrogen, and diesel. - Factors like fuel type and wide band oxygen sensors that impact ideal air/fuel mixture levels.

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71 views1 page

Air/Fuel Ratio: Here Show Toolbars

The document discusses air/fuel ratios and provides information on: - Different modes the PCM can enter that affect air/fuel ratios such as MAF closed loop and Speed Density open loop. - Units of measure for air/fuel ratios including stoichiometric, lambda, and EQ ratio and how to convert between them. - Typical stoichiometric air/fuel ratios for common fuels like gasoline, natural gas, propane, ethanol, hydrogen, and diesel. - Factors like fuel type and wide band oxygen sensors that impact ideal air/fuel mixture levels.

Uploaded by

Wayne Lund
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Air/Fuel Ratio

 Click here to show toolbars of the Web Online Help System: show toolbars
 

 Air/Fuel Ratio

Changing Wide Open Throttle Air Fuel Ratio

Location: Engine->Fuel Control (Power Enrich


Tab)
Make very small changes and use the scan tool to verify your
adjustments.
Do not rely on stock O2 sensors for accurate readings, use a
wide band O2 for accurate results.
Modifying the vehicles air/fuel mixture can result in damage if
not done properly.
MODIFY AT YOUR OWN RISK!

Air Fuel Ratio Units of measure

Stoichiometric Air Fuel Ratio: This is the Air to Fuel


mixture considered chemically balanced within the vehicle's
combustion chamber.
This number can move up or down dependant upon
the type of fuel being used and what the ideal mixture is
considered. Catalytic
converters are designed to be most efficient
when a clean combustion process has taken place prior to passing
through it. This value is
used as the base to most other fueling
calculations such as Open Loop and Power Enrichment so changing the
stoichiometric table is not
advised in most cases.
Lambda:
EQ Ratio:

Converting AFR Units of measure

EQ Ratio to Lambda: Lambda=1/EQ Ratio


Lambda to EQ Ratio: EQ Ratio=1/Lambda
EQ Ratio to AFR: AFR=Stoichiometric/EQ Ratio

Modes the pcm can enter that affect your Air Fuel Ratio

MAF Closed Loop: MAF is Active, Main fueling O2 sensors


are Active
MAF Open Loop: MAF is Active, Main fueling O2 sensors
are Inactive or removed
Speed Density Closed Loop: Maf is inactive, removed or
Failed, Main fueling O2 sensors are Active
Speed Density Open Loop(OLSD): Maf is inactive, removed
or Failed, Main fueling O2 sensors are Inactive

Stoichiometric Air/Fuel Ratios

Fuel Stoich AFR by weight


Gasoline 14.7:1
Natural Gas 17.2:1
Propane 15.5:1
Ethanol 9.0:1
Hydrogen 34.0:1
Diesel 14.6:1

https://www.hptuners.com/help/vcm_editor_tuning_how_to_basics_afr.htm[4/17/2021 7:21:26 AM]

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