Always lean after tuning

[mriulvr]

Hoping someone has a suggestion for the following issue. i finished tuning my 04 XB12S earlier this summer using a WB O2 sensor and MLV. Below is the finalized fuel map for the rear and I kept the percent change from rear to from that was in the original race map.

afrBins2.jpg

After finishing the tune I returned all the EEPROM settings to what they were pretune. Exhaust valve is turned off as I have a Hawk. I reset the my LC-2 WB sensor to emulate a NB sensor and everything was great. Now I am getting an O2 always lean CEL. Logged my ride today and O2 sensor ranged from a minimum of .371 to a maximum of .601 but primarily varies between around .455 to .525. AFV is at 105% and ambient temp is low 90s to low 100s. My O2 settings are .56v (Rich), .49v (Midpoint), and .41v (Lean).

Below is a scatterplot showing time on the x-axis, O2 on the y-axis, and hits on the z-axis. The vertical white line is where the CEL came on.

O2 scatterplot.jpg

All I can think of is that my settings for the NB emulation are the issue. I set the midpoint, rich, and lean voltages to the same as my EEPROM O2 settings. I do not remember the AFR settings I used but I know I set the midpoint at 14.7. I will check these when I get home tonight.

Should the Rich and Lean voltage for the NB Emulation be the same as the EEPROM settings?
How far above and below 14.7 should AFR be for the NB? Any other ideas?

[ReadyXB]

Did the O2 lean code occur during the same session in which you recorded the stated O2 values? If so, you can create a Custom Field in MLV that isolates the O2 Lean bit in CDiag0. With that custom field, you can do a search and find where it becomes set and then look at the events leading up to it.

If you have a log to share that shows the issue, I'd be glad to take a look.

[mriulvr]

ReadyXB, the CEL tripped during the logged ride I posted. The CEL tripped at about 708 seconds into the ride. Prior to the CEL the average O2 reading was .49v, min .376v, and max .591v. After the CEL the average O2 reading was .476v, min .371v, and max .562v. I'm thinking that it has to be the LC-2 settings. I installed the WB O2 sensor last fall and did a free air recalibration this spring. I'll send a PM with a link to the log. Thanks.

[mriulvr]

Couldn't send the log. When I tried I received the following message.

ReadyXB has exceeded their stored private messages quota and cannot accept further messages until they clear some space.

[ReadyXB]

If you could upload it to dropbox or something similar and pm me a link, that might work better.

[mriulvr]

That's exactly what I tried to do but got the message I posted. Looks like the new site limits the space available for PMs.

[mriulvr]

Weird, just tried it again and it sent.

[ReadyXB]

Thx I'll take a look.
Funny - I tried to reply to your pm, and I got the same message.
The dropbox link was to an empty folder.

[mriulvr]

Apparently did not upload first time but should be there now. Loving technology today.

[ReadyXB]

Got it. After an initial view, I definitely see your symptoms.
You are right on. The O2 signal is not behaving as a normal healthy NB O2 would. The voltage transitions stay within a very narrow margin (as mentioned in your original post). The scatter plot makes this very obvious. The voltage never goes near 0 or 1V, even under acceleration where you would expect to see at least brief dips towards zero.

It is no wonder the ECM logs an O2 error; the ECM never enters closed loop. For the entire ride, it was in Open Loop, even though your engine was fully warm. The reason is because the ECM never thought the O2 sensor was active since an initial transition between rich/lean/rich was never observed.

You could be right about the NB emulation settings. If there are any setting that prevent the min/max voltage from being near 0/1, that could be an issue for the ECM. What are the other settings? Is the response speed set to 1/3 sec? Are you using Analog out 2 or 1 with the defaults?

Also, the battery voltage looks a bit more erratic than I am used to seeing. Not the min/max values, but just the response in general. Could be nothing though.