Inexpensive Air Fuel Ratio Meter

[VRYQUIK]

Here is an inexpensive Air Fuel Ratio Gauge that will fit Harley FLHT bikes. I installed the gauge in place of the air temp gauge.
You can run two wires from the gauge to the O2 sensors. It is a narrow band meter so, you can tap into the factory O2 sensor.



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For models that don’t have O2 sensors, You can Install O2 sensor bungs in the exhaust and use these inexpensive O2 sensors.
Advance Auto Parts Part No.11027
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Narrow band sensors do not work well for tuning but, it will help the “do it yourselfer” to locate rich and lean running areas. If you have a mixture problem area you can mark your throttle position with tape and remember what RPM that it occurred and which cylinder that the problem occurred so you can advise your tunner.



Another advantage of the meter is you will see the meter show lean if you ever get an intake leak such as the intake manifold gasket.

On 2007 & newer bikes, the meter should fluctuate rapidly when the fuel system is in closed loop. When you decelerate, the meter should show lean. Under heavy throttle the meter should be in the lower yellow lights. Your mixture is probably very rich if the gauge is in the high yellow.

This video will show how the meter acts when in closed loop by the rapid movement of the lights. The reason that the lights move rapidly is because the O2 sensor creates it’s on voltage and the ECM is designed to read this voltage and continually compensate and correct the mixture. So basically it will run rich then lean while trying to adjust the mixture to 14.6:1 AFR.
If it goes into open loop, the ECM no longer tries to correct the mixture and the gauge will read more steadily. The gauge will read steady on 2006 and older bikes w/o a closed loop fuel system.

Notice that when I give the bike more throttle, the lights go steady yellow. When I decelerate the lights go lean (red).

Sorry about the video being sideways, but it was the only way to shoot the video with the camera mounted.

YouTube - Harley AFR Meter

[EZE RIDER]

Pretty cool.

[shovelmike]

Wow! Thanks for the post. Very useful info, as are the others you've posted. That's part of what makes this forum the best. You're always coming up with great stuff!

[rjrivero]

Nice setup.

I use a Twinscan II plus. It has the WEGO 02 sensors and stores the data in a flash memory system so you can download it to your laptop. You can change your sampling intervals so you can get data on a nice long highway cruise, or on a dragstrip. The benefit of this system is that you don't have to mark your THROTTLE position, or your RPM's. It reads the BUS info right off the data link, and gives you all of the particulars. It will tell you exactly which cells need tweaking in your SERT or PCIII formatted map.

A second benefit of this system is you can continue to have your target AFR's 12.8 to 14.6 or anywhere else you'd like. You're not stuck with ONE target AFR.

[shovelmike]

Wow, RJ, that Twinscan system sounds like a very sophisticated setup, quite possibly more technology than I can wrap my mind around, though I'm trying hard to catch up to it all.

[rjrivero]

It's really not all that bad. You need to read the manual a couple times to get into the mindset, and then go through the setups and step by step procedures. It tells you EXACTLY what you need to do and how you need to do it to get your bike tuned properly. You can use PCIII tables or SERT tables.

Their website is here. Link Here.

[shovelmike]

Thanks for the link, RJ. I'll check it out.

[evoKENevo]

Thanks for the link RJ...I'm not an EFI guy,but checked it out anyhow...and found a WEALTH of IGNITION and OTHER tuning info there...incld'g (not limited to) recommended AFR for start-up,idle,cruising & WOT,etc.

Good reading for ANY gear-heads.