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SAFR Fuel Tuning


Like any electronic device you need to know the basic operations before you can fully start to use the equipment. Don't worry though, the SAFR will have you understanding your tune-up in seconds. There is NO COMPLEX SOFTWARE program for you to learn. Just make the installation and go for a ride.

  1. Understand General Terminology
  2. Understand AFR values
  3. Narrowband vs Wideband O2 Sensors
  4. Installation


Air-Fuel Ratio (AFR) - The most common reference term used for mixtures in internal combustion engines. It is the ratio between the mass of air and the mass of fuel in the air-fuel mix at any given moment.

Oxygen (O2) Sensor - Is an electronic device that measures the proportion of oxygen (O2) in the exhaust gas.


AFR Values & Characteristics in Four Stroke Engines
 6.0 AFR - Rich Burn Limit (engine fully warm)
 9.0 AFR - Black Smoke / Low Power
11.5 AFR - Best Rich Torque at Wide Open Throttle
12.2 AFR - Safe Best Power at Wide Open Throttle
13.3 AFR - Lean Best Torque
14.6 AFR - Stoichiometric AFR (Stoich)
15.5 AFR - Lean Cruise
16.5 AFR - Usual Best Economy
18.0 AFR - Carbureted Lean Burn Limit
22.0+ AFR - EEC / EFI Lean Burn Limit

Lean Conditions - Common Side Affects
Hotter Engine Temperatures
Detonation / Pinging
Hesitation in Throttle Response

Rich Conditions - Common Side Affects
Engine Flooding
Decel Pop / Backfiring
Lethargic Throttle Response
Excess Carbon Build-up (sooty pipes)
Fuel Smell from the Exhaust


Due to emission regulations the use of O2 sensors has become prevalent in the powersports industry on OEM vehicles. The concept of implementing an auto-tune / closed loop / self mapping fuel control system has also become prevalent in the after-market tuning industry. A huge misunderstanding results from the type of O2 sensors which can be used in each application. The AFR+ system uses a wideband O2 sensor to display the full range of AFR values and target performance AFR values along with fuel economy AFR values.

A Narrowband O2 Sensor is only calibrated to know whether the current AFR is rich, lean, or stoich. The sensor targets a NARROW range around the stoich AFR value of 14.6 to help stock ECU systems fuel trim to meet emission standards.

A Wideband O2 Sensor is much more sophisticated and can supply the exact AFR measurement across a WIDE range of possible AFR values.


Key Features Find Dealer Installation Contact
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SAFR Basics Product Discounts AFR Values to Target Twitter
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