To analyze the air/fuel mixture the system uses an oxygen sensor to sample the exhaust gas. The sensor samples the exhaust and measures the amount of oxygen present in the spent gases using a wide band oxygen sensor. When used as part of a computer controlled feed-back system the oxygen sensor tells the computer, via a small electric signal, when the air/fuel ratio is rich, too lean, or just right. The computer reacts to the signal by re-calibrating the fuel delivery system thousands of times per second. This feedback control loop, or closed loop system, maintains a near perfect air/fuel ratio throughout the entire operating rpm range. Your K&N Air/Fuel Monitor uses this same electric signal to illuminate a group of 10 LED lights that correspond with an air/fuel ratio scale. Reading the scale will tell you immediately if your fuel calibration is rich, lean, or just right. Using the Monitor as a tool a tuner can adjust for peak performance, economy, or drivability under any load, condition, or throttle opening. Detailed instructions available for download below. A chart showing general guidelines is below.
Light 1 Light 2 Light 3 Light 4 Light 5 Light 6 Light 7 Light 8 Light 9 Light 10
Gasoline 17.1 16.0 15.1 14.7 14.7 14.7 14.7 14.0 13.2 12.1
Alcohol 7.6 7.1 6.7 6.5 6.5 6.5 6.5 6.1 5.8 5.3
Propane 17.9 16.8 15.9 15.6 15.6 15.6 15.6 15.0 14.0 13.0
The monitor reads oxygen left in the exhaust regardless of what fuel is used and so the number of lights and the corresponding scale remains the same. The monitors have red, yellow, and green lights that require 100 millivolts per light for a total of 1.0 volt.
A K&N Air/Fuel Monitor has many uses. For example, it can be used as a guideline for preparing a vehicle for emissions testing, or as a piece of dynamometer test equipment. It can be used to calculate the amount of carbon monoxide (CO) and hydrocarbon (HC) emissions as related to the air/fuel ratio. Leaning out the air/fuel mixture reduces CO and HC emissions. The Air/Fuel Monitor can also be a helpful tool when setting the idle mixture screws on an engine equipped with a large camshaft and automatic transmission. Chock the wheels, start the engine, and put the transmission in drive. Adjust the idle mixture screws until the 8th light on the Monitor glows steady. The engine should then idle in drive without stalling.
Installing an oxygen sensor in each exhaust pipe is an excellent way to confirm a fuel distribution problem. If you would like to monitor both banks then install a second oxygen sensor in the bank 2 pipe. Then switch between the sensors with a switch (purchased locally).
Kits are available in round or rectangular styles, be sure to select your style before adding to your cart. All replacement parts are available including the wide band oxygen sensor, weld on bungs, bung plugs, and mounting bezels.
- Product Style: Accessories
- Weight: 0.54 lb (0.25 kg)
- Product Box Length: 12 in (305 mm)
- Product Box Width: 9.06 in (230 mm)
- Product Box Height: 2.5 in (64 mm)
**** NOTICE ****
The oxygen sensor in your K&N Air/Fuel Monitor assembly is not compatible with leaded fuels or any fuel additive containing lead. Leaded fuel will contaminate the oxygen sensor causing it to deliver a false reading. The Monitor can however be used to momentarily test an engine burning leaded fuel. Simply install the sensor, quickly re-calibrate the fuel delivery system to deliver the desired air/fuel ratio, then remove the sensor to avoid prolonged exposure. This short term exposure will extend the useful life of the sensor when testing an engine burning leaded fuel but eventually it will become contaminated. Once contaminated the sensor must be replaced to restore the accuracy of your instrument. Additionally, since there is no efficient way to test the sensor, there is no way to determine the level of contamination. Therefore, we recommend periodically comparing a used sensor to a new one.
Other products that will contaminate or clog the sensor are:
- Gas/oil mixture • Injector or carburetor cleaners contain lead additives
- Octane boosters containing lead
- Other “secret potions”