Lazy Oxygen Sensors

[VDeuce]

Just thought I'd pass this on...

I just ordered 2 new stock O2 sensors as my rear one is displaying lazy characteristics. Interesting things is that they only had perhaps 6000 miles on them. This is on a 2007 Street Glide.

The data recordings showed the front sensor kick in about 30 seconds after cold start, with the rear not responding for a few minutes. When they both finally warmed up, you could blip the throttle, watch the spike in RPM and the front responded crisply, whereas the rear would take a lot of time. The rear almost always read a higher voltage than the front.

As a result, my TTS VTune sessions were resulting in too great of a difference between front and rear VEs (like 20%). I also did a compression test (both cylinders were dead on), intake leak test, and exhaust leak tests. All those passed.

If I'm correct, the lazy O2 sensor would result in an over-rich mix.

Now for a question: should a small amount of anti-sieze be applied to the threads of the new sensors, or is doing this perhaps a risk to the new sensors? Assuming none gets on the probe itself...

[Doc 1]

Just thought I'd pass this on...

I just ordered 2 new stock O2 sensors as my rear one is displaying lazy characteristics. Interesting things is that they only had perhaps 6000 miles on them. This is on a 2007 Street Glide.

The data recordings showed the front sensor kick in about 30 seconds after cold start, with the rear not responding for a few minutes. When they both finally warmed up, you could blip the throttle, watch the spike in RPM and the front responded crisply, whereas the rear would take a lot of time. The rear almost always read a higher voltage than the front.

As a result, my TTS VTune sessions were resulting in too great of a difference between front and rear VEs (like 20%). I also did a compression test (both cylinders were dead on), intake leak test, and exhaust leak tests. All those passed.

If I'm correct, the lazy O2 sensor would result in an over-rich mix.

Now for a question: should a small amount of anti-sieze be applied to the threads of the new sensors, or is doing this perhaps a risk to the new sensors? Assuming none gets on the probe itself...

Use a lead free antisieze or 02 safe anti-seize.....it will tell you on the lable if it 02 safe or lead free.

[Ram]

My new o2 sensors came with the proper amount of anti-seize pre-applied where it belongs, during production and covered with a protective cap to keep it from making a mess in shipping. 

Remove cap and install in pipe.  Be sure to have pipe threads clean before hand and start threads straight.  Cross threading will be a real PITA for removal some day.

[WVULTRA]

VDeuce:

Recent check of the sensors coming on-line:



Front started ~28 secs. and rear at ~64 secs.  These were replaced ~2000 miles ago, and as others stated they already had anti-seize applied along with protective caps on the probes.

[VDeuce]

Thanks guys, I bet the new ones do come with the goop on 'em. Hopefully they arrive soon so I can get this tuned.

WVULTRA: Yep, that looks correct. My front looks like that, but the rear is almost non-responsive. There are times when the throttle is blipped that it doesn't even react, or when it does, it is way late (I guess lazy really fits)! I noticed in your log that the engine isn't that warm and therefore the sensors are still reading pretty high values. Even when my engine reached over 200*F, it the rear would still read around 1600mV, whereas the front was in the normal 100-900mV range.

One other perhaps telling sign is that the O2 rich/lean status bit in the upper right corner was often displaying a 1, perhaps indicating an issue (but I see yours has this as well, and I don't really know what this is telling us). No DTC codes were stored though.

[WVULTRA]

One other perhaps telling sign is that the O2 rich/lean status bit in the upper right corner was often displaying a 1, perhaps indicating an issue (but I see yours has this as well, and I don't really know what this is telling us).

VDeuce:

From the MasterTune Help Files:

Data Item Descriptions:

Engine Running Status Bit:
This bit is set to ONE after the motor has started.

Vehicle Tipped Status Bit:
This bit is normally ZERO unless the vehicle is tipped more than 45 degrees.
See Also BAS - Bank Angle Sensor

VTD Active Status Bit:
This bit is ONE if the Vehicle Theft Deterrent mode is active.

Feedback Rich â€" Lean Status Bit:
For Oxygen-sensor equipped vehicles, this status bit indicates if the front cylinder is running in a rich or lean condition. This bit is ONE if the mixture is rich and is a ZERO if the mixture is lean.

[VDeuce]

One other perhaps telling sign is that the O2 rich/lean status bit in the upper right corner was often displaying a 1, perhaps indicating an issue (but I see yours has this as well, and I don't really know what this is telling us).

VDeuce:

From the MasterTune Help Files:

Data Item Descriptions:

Engine Running Status Bit:
This bit is set to ONE after the motor has started.

Vehicle Tipped Status Bit:
This bit is normally ZERO unless the vehicle is tipped more than 45 degrees.
See Also BAS - Bank Angle Sensor

VTD Active Status Bit:
This bit is ONE if the Vehicle Theft Deterrent mode is active.

Feedback Rich â€" Lean Status Bit:
For Oxygen-sensor equipped vehicles, this status bit indicates if the front cylinder is running in a rich or lean condition. This bit is ONE if the mixture is rich and is a ZERO if the mixture is lean.

Thanks for the clarification!

When I get a chance, I will do a data log of the lazy sensor so people can see what these look like...

[Don D]

Rear pipe?
Stock bagger duals?
Could the fact that the pipe is being fed cold air from the left pipe have anything to do with the slow response and could this be messing with VE settings also?

[ViennaHog]

Did a 2009 Dyna the other day with SE slip ons and the rear cylinder came on only seconds after the front. Supports Don's suspicion. Will check if I get my hands on a shorty dual late model. Lazy sensors on my 2008 Ultra led to a rpelacement at 16,000 miles. Had some strange VE readings rear cylinder.

[VDeuce]

D&D Fat Cat exhaust. I'll see if I can get a log done and posted tonight. Get the popcorn ready! 

[WVULTRA]

If there's a concensus that the rear O2 Sensor if failing first or before the front, would the hotter running rear cylinder be a contributing factor?

[Scramjet]

We just had two 2007 touring bikes dynoed at Roeder Racing.  We checked the O2 sensors on both bikes.  The FLHTC has stock head pipes with Jackpot slip-ons and an FLHX with D&D.  Both bikes had the rear O2 come on very late with the engine warm at idle.  The first O2 had about 2,000 miles on them and the second bike had about 1,000 miles on the O2's.

On Herko's advise we ran up the idle to heat the sensors and "bingo", the rear 02's came on with good voltage on both bikes.  Both bikes had been V-Tuned with the TTS and both bikes had dyno ARF's consistant with the TTS programmed AFR indicating that the O2's were working.  Just not heating up as fast at idle.

B

[Steve Cole]

On bikes with aftermarket slip-on's and a touring style pipe there can be issue with the rear cylinder coming up slower due to the free flow of the exhaust and sensor position. If there is enough of a free flow the left hand muffler allows air to enter the pipe and be pulled up to the sensor area at low engine speeds. This causes the sensor to cool so it will come on line later. The free'r flowing, the louder it is, the slower the rear becomes.

[Vosselman]

Swap front and rear 02 sensor and check again.
If the 'problem' goes to the other cylinder, it's the sensor. If the problem is still on the same cylinder, it's not the 02 sensor.

[Scramjet]

Swap front and rear 02 sensor and check again.
If the 'problem' goes to the other cylinder, it's the sensor. If the problem is still on the same cylinder, it's not the 02 sensor.

Yup, see my post above.  We swapped the O2's on the FLHX with the same slow response results from the rear cylinder.  It was NOT the sensor, it was a position and heating issue with both exhausts.

B

[VDeuce]

I'll check 'em out. Won't be able to get to it for a few days. I'll report my findings....

[Don D]

Suspect the sensor is bad still?
Swap them then monitor

[AkMan]

Just thought I'd pass this on...

I just ordered 2 new stock O2 sensors as my rear one is displaying lazy characteristics. Interesting things is that they only had perhaps 6000 miles on them. This is on a 2007 Street Glide.

The data recordings showed the front sensor kick in about 30 seconds after cold start, with the rear not responding for a few minutes. When they both finally warmed up, you could blip the throttle, watch the spike in RPM and the front responded crisply, whereas the rear would take a lot of time. The rear almost always read a higher voltage than the front.

As a result, my TTS VTune sessions were resulting in too great of a difference between front and rear VEs (like 20%). I also did a compression test (both cylinders were dead on), intake leak test, and exhaust leak tests. All those passed.

If I'm correct, the lazy O2 sensor would result in an over-rich mix.

Now for a question: should a small amount of anti-sieze be applied to the threads of the new sensors, or is doing this perhaps a risk to the new sensors? Assuming none gets on the probe itself...

Well, finally got back home. The bike is running fine once again after a stop along the way at Thunder Mountain HD in Loveland CO.
The front o2 went bad. The service mgr said that they have seen alot of them go bad for the past year.

[VDeuce]

I never redid a trace on the old sensors. I had the bike apart for fork work and just replaced both sensors. They both are operating fine. They both come on sooner and react quickly.

Time for another VTune session!

[Don D]

Have you considered when the VEs are set right to turn off closed loop

[VDeuce]

Have you considered when the VEs are set right to turn off closed loop

Not sure. I am by no means a tuner and am really just trying to get the VEs right at this point. I have considered turning closed loop off - only experimentation though.

It's certainly easy enough to do and do some logging runs.

I can say this; it's never run better, but I also did an exhaust change and 51mm TB at the same time.

I'm always open to tuning suggestions!