Can someone explain to me with the EFI system when the bike runs in the Closed Loop Mode and when the bike runs in the Open Loop Mode. I hear these terms a lot and just wanted to educate myself a little more.

Thanks

 

https://www.hdforums.com/m_367341/mpage_1/key_/tm.htm

Okay foudn this link in the forum to answer my own question but if anyone else has any input I will take it.

 

The link described it pretty well. I can comment on it maybe a bit further, but this is all from auto experience.
In open loop, that is the warm up mode. On a car, the mixture is set by the coolant temp sensor, and the mixture (fuel injection duration) is set solely on that.
Once the coolant temp is warm enough, the mixture is set by the O2 sensor(s). When the mixture is too rich, the mixture drives lean, then when the mixture is too lean, the mixture drives rich, achieving a relationship called lambda.
Now with more modern engines and the intro of mass airflow sensors, the amount of fuel that needs to be injected can be predicted by the engine control unit a lot closer and the injection system can nail that mixture without much fluctuation, but ultimately the O2 sensor is the final judge on what needs to be done to the mixture. So the meaning of closed loop means you have completed the loop of information, from the O2 sensor to the control unit to the fuel delivery itself, (lambda). Open loop means control unit just uses the engine temp to control the fuel mixture, no feedback from the O2 sensors.
The really important thing these days is to get the engine warmed up ASAP to get the system into closed loop faster.
Gilly

 

Gilly thanks for the response. Does what you explained in a vehicle apply to the motorcycle was well and if I understand it correctly the only time the bike will be running in the Open Loop mode would be during warm up and then once the engine is warmed up the bike will then be in Closed Loop mode until shut off and restarted again after cooling off?

 

No expert here but I did come across this from a post on here somewhere and saved it.

Enjoy ...

EFI Map matrix

How does the EFI system work in simple terms?
The EFI system used on most 06 and earlier models is an open loop system. This system is essentially “dumb” in the sense that it supplies fuel based only on the programmed (calibration) values in the tables that control the injectors. These calibration values are programmed by H-D to match the amount of/how an average stock motor, and its associated components, processes air at any given rpm, load and throttle opening. Environment changes (temperature, altitude, etc) are handled by offset tables which collect information from sensors (IAT, ET, MAP, etc) to modify the main tables. There are “Tuning Constants” that define the overall operational parameters such as motor size, injector size and rev limit. Another offset is the AFR table which uses a mathmatical formula to change the known tailpipe AFR base tuned value (when motors are stock using the original mapping) to the "desired AFR" for best fuel milage and low emmissions. The calibration values are fixed in the open loop system (until physically changed via remapping) and the ECM is incapable of identifying changes in air flow caused by component changes and corresponding needs to make fuel or other calibration changes to synchronize air/fuel or correct constants.
06 Dyna’s and all 07L models (except 07 V-rod) added O2 sensors in the exhaust systems to provide a “closed loop” capability. Production variables of the components used in and affecting the EFI system cause corresponding fuel and air flow differences from bike to bike as manufactured. The fixed, “open loop”, system does not compensate for these differences (just as it cannot compensate for component changes). The Closed Loop O2 sensing system provides feedback, within a limited AFR and specified operating range, to compensate for these production variables, reducing overall emissions. This added feature can compensate for mild component changes but does not memorize those changes (there is an "Addaptive Fuel Value" offset based on the avereage O2 required corrections which moves the entire VE tables rich /lean by +- 10%, remembered and constantly adjusting). This means that each time the ignition key is cycled, the O2 correction (O2 integrator) is at zero and must resample to establish the required correction. The bike may exhibit erratic running, until this is accomplished, each time it is restarted if the required correction values are large.

When do I need to recalibrate my ECM?
Whenever the amount of, or how the motor processes air is changed! Period!!! The major components influencing air flow are the exhaust system, air cleaner, motor size, heads and cams. If any of these are changed, the fuel (via the VE and AFR tables) and, typically, the tuning constants table in the ECM must change to match (synchronize) both the increases and decreases in air flow and physical characteristics of the motor caused by those component changes.
On “closed loop” models, the above is true when the changes exceed the O2’s capability to compensate, to reduce the amount of correction required of the O2's or to change tuning constants (motor size, injector size, etc).
In addition, there are certain “behind the scenes” tables that have strategies to add fuel for extended high rpm running or heat management, retard timing for knock control or heat management, injector off timing to reduce decal pop, change VE values (O2 equipped models AFV) or even to deal with high rpm downshifts in efforts to prevent engine damage or reduce ECM workload in extreme cases. Even with Race Tuner, we normally do not have access to these tables and cannot change them. These stratigies/tables may be diff

 

I'm not sure how the temp thing works on a HD, I'd assume on an air-colled engine it would determine engine temp via oil temp, not coolant of course. I'd also assume when FIRST started with a relatively warm engine, it would operate in open loop, but will go into closed loop much faster.

 

Some pretty good explainations so far, but I sawa couple of things that I thought were a bit missleading. Again, from the automotive side.. (Same EPA driving emissions regulations)..

The term Open Loop simply means that the system is working in a Non-feedback mode. Meaning the info from the O2s is not being used to control fuel delivery. The PCM(ECM, or just module) is working off a preset or learned value for that operating range. Not having an EFI bike, I would immagne there is an oil temp sensor to provide engine temp info. Of course thereare also athrottle possition sensor, manifold pressure sensor(at least until they add a Mass Airflow sensor)and tach signal. This info from these sensors will provide a pretty good guess as to how much fuel is needed at any given time. The OL (Open Loop) strategy should run to the rich side of stochiometric(14.7:1 air fuel ratio) for a couple of purposes. #1 on the list would be that lean is bad, it creates excessive heat, engine damage, detonation and NOx. You will see OL on initial start up, until the O2s warm enough and start providing a reasonable signal. If they are heated (I assume they would have to be on bikes too) this should happen really quickly(like, less than 1min.). You will also see OL when you go to wide open throttle, decel from WOT, and excessive idle time to name a few.. The point is, that in OL, you are defaulting to a rich condition. This isnt good for emissions(the goal) but rich is ideal for WOT(more power to get out of the way of the bus), decel and extended idle(to reduce heat created by these conditions in the catalytic converter).

Closed loop is simply that, a closed information loop that provides feedback to allow the PCM to adjust the fuel delivery for optimum emissions and performance(in that order)..