Richen the HD Narrow Band O2 Sensor

A narrow band O2 sensor (NBO2) essentially only understands a 14.7:1 air fuel ratio (AFR). Here is a little trick that can be used that will richen the AFR to approximately 14.2:1. While this is still not an ideal AFR for idle and cruising, it is an improvement.

This change in AFR should reduce heat at the exhaust heat shield from 200 degrees F to 160-180. The probability of the engine going into overheat mode should be reduced 75+% of the time. Considering the low cost of this device, that makes it a very cost effective upgrade to help manage the fuel mixture when the ECU is running in closed loop mode.
VDC Schematic is no longer available.

Nightrider's O2 IED is now "patent pending" technology

 How we designed the NBO2 Richen circuit

In the Harley-Davidson O2 sensor wiring harness, the Blue wire is the (+) or sensor signal wire. The Gray wire is the (-) or ground wire. We designed a voltage divider circuit that slightly reduces the voltage the Delphi ECM sense from the O2 sensor which forces the engine to run at a slightly richer fuel ratio.


Nightrider's NBO2 sensor Inline Enrichment Device

Installing the NB O2 Inline Enrichment Device (IED)

Locate the O2 sensor in the front/rear exhaust pipe.
Follow the wiring from the HD O2 sensor to the connector. This should be about 6-8” from the O2 sensor.
Disconnect the O2 sensor from the wiring harness. It will probably be easier to get to the rear wiring harness connector by removing the seat.
Connect the female connector end of the VDC to the male connector on the HD O2 sensor.
Connect the male connector end of the VDC to the female connector of the HD wiring harness.
If you want, you can use tie wraps to hold the VDC in place.
You installation is complete and you are ready to go.

Testing the NBO2 Inline Enrichment Device off the bike

If at any time you think your IED is not working properly, you should first make sure the connectors are properly plugged in and are tight. If you still feel there is an issue, you need to remove it from the bike first. Test your IED with a 1.5V battery, 2 paper clips and a volt meter. First you need to check the battery to make sure it is producing 1.5V. Open up the paper clips and install them into the female connector (wiring harness side). Touch the battery to the paper clips so the (+) side is on the blue wire site and the (-) on the grey side. Touch the voltmeter to the male connectors (wiring harness side). You should see 1.00 to .90 volts or about 30% less than the battery voltage. If the correct voltage is present, the IED is working correctly.
Voltage Output from a typical narrow band O2 sensor

The most accurate range for narrow band O2 sensors is the .400v to .800v or the 15.0:1 to 14.2:1 AFR ranges. Once the fuel ratio is outside these limits, the accuracy of measurement rapidly changes. This is why narrow band oxygen sensor are considered a 14.7:1 AFR voltage switch.

The voltage divider works by taking advantage of the accurate range of the O2 sensor and some simple electronics to allow .750v output from the O2 sensor to look like .500v to the fuel injections system.

 

 

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-Parts listed on this site that alter fuel mixtures or replace OEM pollution control devices are for Race Only Purposes. Check with local regulations and laws to ensure compliance. In California, Race Only products must not be used on any vehicle that is registered or licensed for use on public roads.
- References to Harley-Davidson and H-D makes, models and other trademarks are for reference purposes only and do not constitute affiliation or endorsement by Harley-Davidson Inc.
-Air Fuel Ratio's (AFR) represented for these products are based on exhaust gas temperatures (EGT) of 1400-1500 F. Cooler EGT during startup, cooler weather or during some dyno testing with cooling fans can result in .5 to .8 leaner AFR's. This is normal due to the way unheated narrow band O2 sensors react to changing EGT's. The "hotter" the engine gets, the better the IED's actually work.
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Copyright 2007-2010 PG Mullen, S&P Mullen Enterprises, Inc., 313-444-XIED(9433) , Oldsmar, FL 34677