Question about O2 sensors and tuning

[GoSlo]

A few years back I had my TriGlide dyno'd and remember being told that the tuner bypassed the O2 sensors. Is that good or bad? I don't have any idea.

 

[FuzzyWuzHe]

A few years back I had my TriGlide dyno'd and remember being told that the tuner bypassed the O2 sensors. Is that good or bad? I don't have any idea.

As in removed from the closed loop? I would think that was a bad thing.

The ECM in closed loop is probably the best the trike will run ... IMHO

 

[GoSlo]

As in removed from the closed loop? I would think that was a bad thing.

The ECM in closed loop is probably the best the trike will run ... IMHO

I honestly don't know. Seems a bit odd to me now that I know a very, very tiny bit more about tuning then I did then. Just curious what others thought.

 

[msocko3]

I honestly don't know. Seems a bit odd to me now that I know a very, very tiny bit more about tuning then I did then. Just curious what others thought.

If it runs good and returns respectable fuel mileage I wouldn't loose sleep over it. One of the biggest benefits of the O2 sensors is the ability to compensate for differences in fuel. If the person who tuned it did their job getting the VE tables right, it would be easy to put areas in closed loop and see what you think. I'd imagine your O2 sensors are still installed and hooked up, they just took them out of the picture by putting the AFR tables in open loop.

 

[mcdonaldroadcapt]

As in removed from the closed loop? I would think that was a bad thing.

The ECM in closed loop is probably the best the trike will run ... IMHO

Totally agree. Tried a Dynojet tune with removing O2 sensors and it was the worse running engine I have ever experienced. Quit on me in Daytona and only wanted to start running of front cylinder only. Finally got home and removed all, replaced my sensors and got back to enjoying. Since then, a TTS Master Tune by Mr. Wiz and best running bike I've owned.

 

[msocko3]

Totally agree. Tried a Dynojet tune with removing O2 sensors and it was the worse running engine I have ever experienced. Quit on me in Daytona and only wanted to start running of front cylinder only. Finally got home and removed all, replaced my sensors and got back to enjoying. Since then, a TTS Master Tune by Mr. Wiz and best running bike I've owned.

:Agree: Couldn't agree more. I went with O2 sensors on my 06 Ultra because the ECM would support them. It's tuned with the TTS, I've ridden it both ways, open loop and closed loop. It runs the best and gets the best gas mileage when in closed loop.

 

[Sloufoot]

Totally agree. Tried a Dynojet tune with removing O2 sensors and it was the worse running engine I have ever experienced. Quit on me in Daytona and only wanted to start running of front cylinder only. Finally got home and removed all, replaced my sensors and got back to enjoying. Since then, a TTS Master Tune by Mr. Wiz and best running bike I've owned.

Never have heard of doing that. But like Mike mentioned, tuning many times takes the O2's out of the mix. The new Power Vision when used with the new Target Tune module lets the ECM use the wide band O2's so you can stay in closed loop full time with a very wide area for the AFR to be set at.
I have this set-up & I can say I have NEVER had a Harley that runs as smooth as it does right now ! Money well spent !

 

[DakotaTG]

I have a 2011 Merlot and Black TG that has the cat removed, CVO mufflers and a stage 1 with the Power Commander V installed. This was all done back in the summer of 2011. This spring I had some trouble with the engine running poorly and some backfiring. The problem ended up being both automatic compression releases were bad and the compensator was going. A new compensator and releases were installed and dynoed. When I picked it up after the work was done they mentioned that my O2 sensors were still hooked up and with the Power Commander V they shouldn't be connected so they disconnected them. The TG runs fine but my gas mileage is lousy. I'm betting only 20 to 25 mpg running 75 on interstate and 25 to 28 running on two lanes roads around 65. So are the disconnected O2 sensors part of the problem with my gas mileage and should they be reconnected or did I get a bad dyno? I would appreciate any advise.

 

[Sloufoot]

I have a 2011 Merlot and Black TG that has the cat removed, CVO mufflers and a stage 1 with the Power Commander V installed. This was all done back in the summer of 2011. This spring I had some trouble with the engine running poorly and some backfiring. The problem ended up being both automatic compression releases were bad and the compensator was going. A new compensator and releases were installed and dynoed. When I picked it up after the work was done they mentioned that my O2 sensors were still hooked up and with the Power Commander V they shouldn't be connected so they disconnected them. The TG runs fine but my gas mileage is lousy. I'm betting only 20 to 25 mpg running 75 on interstate and 25 to 28 running on two lanes roads around 65. So are the disconnected O2 sensors part of the problem with my gas mileage and should they be reconnected or did I get a bad dyno? I would appreciate any advise.

First, what O2's do you have ?

If they are the original they are the narrow band & might not be able to read what the tuning set the AFR at. But if done correctly they should have left a "cruse" area still in the area the O2's could read. Unless you installed the Auto Tune module with the PCV, you most likely don't have the wide band O2's anyway.

The PCV still lets the ECM read the O2's ! If they did a dyno without the PCV then hooked up your PCV without doing the tune all together you will have problems.

Just hook the O2's back up & see what happens. Most likely they just unplugged the wires. If that doesn't solve your problems, take it back & make them do it right ! Sounds like they don't know what they are doing !

 

[msocko3]

I have a 2011 Merlot and Black TG that has the cat removed, CVO mufflers and a stage 1 with the Power Commander V installed. This was all done back in the summer of 2011. This spring I had some trouble with the engine running poorly and some backfiring. The problem ended up being both automatic compression releases were bad and the compensator was going. A new compensator and releases were installed and dynoed. When I picked it up after the work was done they mentioned that my O2 sensors were still hooked up and with the Power Commander V they shouldn't be connected so they disconnected them. The TG runs fine but my gas mileage is lousy. I'm betting only 20 to 25 mpg running 75 on interstate and 25 to 28 running on two lanes roads around 65. So are the disconnected O2 sensors part of the problem with my gas mileage and should they be reconnected or did I get a bad dyno? I would appreciate any advise.

The PCV doesn't use the factory O2 sensors, the installation instructions even tell you to disconnect them and even removed them if you like.

The problem you're experiencing is a dyno operator who doesn't know how to tune properly for a blend of power and fuel mileage.

IMO I'd step up to a more modern flash tuner such as the TTS or Power Vision. With the flash tuner you don't have the need of a piggy back device such as the PCV, also the flash tuners allow the use of the factory O2 sensors, which helps with fuel mileage.

- - - Updated - - -

First, what O2's do you have ? If they are the original they are the narrow band & might not be able to read what the tuning set the AFR at. But if done correctly they should have left a "cruse" area still in the area the O2's could read. Unless you installed the Auto Tune module with the PCV, you most likely don't have the wide band O2's anyway.

The PCV still lets the ECM read the O2's ! If they did a dyno without the PCV then hooked up your PCV without doing the tune all together you will have problems.

Just hook the O2's back up & see what happens. Most likely they just unplugged the wires. If that doesn't solve your problems, take it back & make them do it right ! Sounds like they don't know what they are doing !

The PCV install instructions tell you to disconnect the O2 sensors.

 

[Sloufoot]

Never read that with my old PCV.... Must of missed something. I always tuned the cruse area around rich side of closed loop.