I know that when using the PCIII, it eliminates the O2 sensors. What effects would it have if you didn't use the O2 sensor eliminators and just disconnected the O2 sensors with the PCIII - would that work? What is the purpose of the O2 sensor eliminators?

 

It might work the same with/without the O2 eliminators connected, but it might also drop into "limp-home" mode. The manual for the Daytona Twin-Scan makes it sound like it would just revert to the set AFR points in the programming. But either way you will get error codes thrown by the computer since it cannot "see" the sensors (or the eliminators).

One thing I can tell you is do not hook the O2 sensors back up normally while using the PC-III to alter fuel anywhere the computer will be looking at the sensors. If you do, things get ugly.

The purpose of the eliminators is to keep the engine computer from trying to remove your PC-III fueling changes and to prevent error codes regarding the O2 sensors.

 

Not exactly this thread, but still a PCIII question. Can the PCIII change the rev limits or does that have to be an H-D flash?

 

Yes, Power Commander can increase the rev limit. Rev extend is built into the unit.

 

Excellent Airfuel! Thanks!

 

thanks for the info

 

Here's some info from the PowerCommander website.

My Power Commander came with O2 eliminators, should I use these and what are they?

On bikes that use an O2 sensor in the stock exhaust have a closed loop area that can not be adjusted by the Power Commander alone. If you make adjustments with the PCIII in the closed loop area the O2 sensor will sense these changes and the ECM will alter the fuel curve accordingly. If you want to have full fuel control over the entire RPM range of your bike then you will need to bypass the closed loop area which the O2 eliminators will accomplish. If you are looking for the best fuel economy and not worried about making changed to the closed loop area you can leave the stock O2 sensors connected and still make changes outside of the closed loop area with the PCIII.

Now where is the closed-loop area? Is this it :
http://www.powercommander.com/downlo...ngs/605000.jpg

 

The jpg file was taken from here and refered to the PowerCommander EX model:
http://www.powercommander.com/powerc...mdl=33&yr=2006

 

I already touched on that above where I said "things get ugly". The thing of it is, if you cause a situation where the bike's computer needs to correct the fueling while it's using its exhaust sensors, it will come up with a factor to apply correction everywhere. This corrective factor is only appropriate for an otherwise-correct tune.

So, you could accurately map the PC-III for whatever engine changes you'd made such that the bike's computer could/would control the fueling trim with its exhaust sensors. But doing so would result in an EPA-correct situation, and for most folks, the greater heat that creates was part of the impetus for making changes in the first place, so it wouldn't make much sense, at first consideration, to spend the time/money to do that.

To be sure, the use of the exhaust sensors is a better situation than the elimination of them, but in practice the latter case is more than sufficient. Especially if you desire the engine running a little richer than it came from the factory.