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O2 sensors and EJK

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Streetglider08

Member
So excuse my ignorance, I have done a search and didn't really find the answer I'm looking for. I'm sure this subject has already been discussed so maybe someone can point me in the right direction. I recently installed the gen3 ejk and unplugged the connecters from the o2 sensor and installed the plugs that I was given from dobeck. My buddies that I ride with asked me why I had my o2 sensors disconnected and I didn't really have an answer. So why is it that you have to unplug the o2 sensor when using this product? I understand that you can't just unplug them but why can't you leave them plugged in? I know that theirs are plugged in with their v&h fuel pack that they are running.
 
Simply unplugging the O2 Sensors may cause the check engine light to come on and leaving them plugged in and the ECM will constantly be trying to override the richer fuel mixture caused by extra fuel you are adding with the TFI Unit. O2 Sensor Eliminators are resistors that send a signal back to the ECM that that O2 Sensors are working properly, even though they are unplugged.

I hope that made sense and did not confuse you even more as my explanations sometimes only make sense to me.
 
Streetglider08 said:
So excuse my ignorance, I have done a search and didn't really find the answer I'm looking for. I'm sure this subject has already been discussed so maybe someone can point me in the right direction. I recently installed the gen3 ejk and unplugged the connecters from the o2 sensor and installed the plugs that I was given from dobeck. My buddies that I ride with asked me why I had my o2 sensors disconnected and I didn't really have an answer. So why is it that you have to unplug the o2 sensor when using this product? I understand that you can't just unplug them but why can't you leave them plugged in? I know that theirs are plugged in with their v&h fuel pack that they are running.
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Streetglider, I just received a Gen3 EJK for my 07 Ultra Classic the other day and will be installing it when the weather permits. That was one of my concerns also about the 02 sensors but, TripleJ gives a good explanation about unplugging them. May have to ask you a few question when I install.
 
Simply put, as TJ documented, your GEN3 & ECM would "battle" each other for control. Because your new tuner controls throttle position to fuel/air ratio - no need for O2 sensors in the mix. I'm sure Dobeck will come through w/more elaborate explanation, but I like layman's terms...:s
 
turnerbend said:
Streetglider, I just received a Gen3 EJK for my 07 Ultra Classic the other day and will be installing it when the weather permits. That was one of my concerns also about the 02 sensors but, TripleJ gives a good explanation about unplugging them. May have to ask you a few question when I install.
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Install is easy if you take your time and follow the directions. I strongly recommend you remove your fuel tank for this install. It's not that hard and allows you to run all the wiring up inside the plastic housing that runs down the spine of your bike. Much cleaner install.

Also, leave the control panel out where you can see it until you're 100% satisfied with the settings. This way you can watch the lights, see what the TFI is doing, and tailor your settings accordingly. I set mine right where the nose of the seat meets the fuel tank - easy to see and not in the way.
 
I understand what you guys are saying. So why do competitors tfi's still use the stock o2 sensors and not have this problem? Don't get me wrong. I have no problem with my dobeck ejk. The power difference I have is amazing. Im just curious, that's all.
 
Streetglider08 said:
I understand what you guys are saying. So why do competitors tfi's still use the stock o2 sensors and not have this problem? Don't get me wrong. I have no problem with my dobeck ejk. The power difference I have is amazing. Im just curious, that's all.
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I will be interested to hear the responses to your question as I am only familiar with the Dobeck Units and the Power Commanders. Not sure why your buddies would be running stock O2 Sensors with the Fuelpak??
 
Streetglider08 -

Responses concerning our controller are correct. In order to make any fuel adjustment within light loads and normal cruising we must bypass the narrowband O2 system. Without bypassing the system as we add fuel the stock ECU would just pull it back out and cause bad drivability. We can not simply disconnect the O2 sensors because this will throw an engine light on most vehicles.

The V&H Fuel Pak also bypasses the O2 system. Pretty much every after-market tuner available has to do something with the stock O2 system. The V&H fuel Pak plugs directly into the ECU which gives them access to the O2 signal at this point. Our controllers stay away from all these other connections and just bypass the O2 system right at the connection. Why? We manufacture an EFI controller for every single powersports industry. This method of installation allows us to stay with a generic controller design and not have to get application specific.
 
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