I have a 2011 FLHTK with an SE air cleaner. I replaced the stock exhaust with V&H Dresser Duals and Rinehart slip ons and bought a TSS tuner. The oxygen sensors are still installed. After having the exhaust upgraded I had it Dyno’d. The Dyno chart showed that it maintains close to a 13.7:1 AF ratio throughout the RPM range. So now my questions:

Does my bike now run in open loop or closed loop in order to maintain the 13.7 AF ratio?

Given that the chart indicates it maintains this AF ratio throughout the RPM range while on the Dyno does that also mean it always maintains this ratio while I am riding it?

I really do not have any complaints with it but I do not understand why the oxygen sensors are still there so are there reasons for them being there? Are they still functioning and/or being used by the FI system?

Thanks!

 

Good question! Wisdom please:-)

 

a dyno run is a "snap shot" of the motor operation under really only 1 kind of operation-- cracked open throttle " roll on" from about 2000 rpms. usually in 4th gear.

dyno data can be skewed in many ways by the operator to "display" a desired result..

maybe poorer numbers on the "before" or better numbers on the "after"

"...see what i done fer ya"

- this is not a blanket statement---- some guys are honest and subjective- others use the dyno and other tricks of the trade to upsell a customer- that is just human nature.




fuel delivery is determined by what the motor is doing- cruising, decel or accel.

and the dyno only tests one of those.

the various sensors input air density, road speed, rpm, throttle position, manifold vacuum ( high on decel, low on accel) and other stuff, the ECM calculates the optimum and the o2 sensors confirm to the ecm whether it is correct.

fuel pressure should be a constant, what is changed is the amount of time ( "pulse width") that the injectors are spraying fuel into the air entering the cylinder


On my old bikes ( pans and evos) I tuned the carbs with o2 sensors in the exhaust stream- o2 sensors output DC voltage at varying amounts depending on the o2 content- and using a simple voltmeter taped to the bars can give readings as to the AFR and whether the motor is running rich/ lean or Goldilocks under real world conditions.

I do the same on my old cadillacs, which is easy. a quick trip to the muffler shop gets an o2 sensor bung welded in for under $50

an o2 sensor outputs more voltage in a rich mixture- less voltage in a lean mixture. stoich is about .45 volts DC

the popular nightrider.com XIEDS are a resistor pack plugged into the o2 sensor wiring which decreases the voltage from the o2 sensor to the ECM...so the ECM "thinks" it is running slightly lean- and makes the mixture slightly richer than it would other wise be.

I cannot comment on the TTS- I have no experience with it

Mike