o2 sensors read rich
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Teching In
Joined: Nov 2023
Posts: 11
Likes: 2
o2 sensors read rich I have a 5.3 turbo setup. Both o2s are in the crossover and just reading LH side. I have a Hooker cast turbo manifold, there is just no good place to put the RH o2 unless I put it right on the manifold. And assume it would take to much heat there.
Anyway I am currently tuning it for SD and dialing in setting for my 80lb injectors. This was an 04 Yukon PCM and harness. I recently changed it to DBC and swapped in an 03 Savanna van PCM to achieve this.
So the problem is my o2s both ride around 700-850mv when my wideband is showing 1.0 lambda. If I enable fuel trims the PCM slowly drives to lean (which makes sense)
To test the o2s I placed one in a bung right next to my Wide band on the down pipe. It still reads rich at 700-850mv.
Is there a different o2 sensor in a van?
I would suspect my WB is wrong but it obviously runs better when the WB is at 1.0 vs at a leaner setting. So I think the WB is set correctly.
Any ideas? Should i try a new o2 sensor? Seems odd if they failed since their readings are pretty close to each other.
It looks like 2002 and down had different wiring on the o2s. But if my wiring was wrong they would just not work right?
Anyway I am currently tuning it for SD and dialing in setting for my 80lb injectors. This was an 04 Yukon PCM and harness. I recently changed it to DBC and swapped in an 03 Savanna van PCM to achieve this.
So the problem is my o2s both ride around 700-850mv when my wideband is showing 1.0 lambda. If I enable fuel trims the PCM slowly drives to lean (which makes sense)
To test the o2s I placed one in a bung right next to my Wide band on the down pipe. It still reads rich at 700-850mv.
Is there a different o2 sensor in a van?
I would suspect my WB is wrong but it obviously runs better when the WB is at 1.0 vs at a leaner setting. So I think the WB is set correctly.
Any ideas? Should i try a new o2 sensor? Seems odd if they failed since their readings are pretty close to each other.
It looks like 2002 and down had different wiring on the o2s. But if my wiring was wrong they would just not work right?
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Joined: Aug 2010
Posts: 7,323
Likes: 529
From: Ann Arbor, MI
First, a narrowband voltage reading on e.g. 750mV corresponds to about lambda .98 (or 14.3 AFR). This might vary a bit depending upon the model sensor, but not a lot. So if your wideband is off by just 2%, that would explain the difference.
Second, a narrowband when working does not show as a constant voltage, but rather a rapidly changing AC voltage between 0 and 1 Volt. The reading you get with a DC meter (or tool) is the RMS (average) voltage of the AC signal. Good meters often advertise "True RMS", but a basic meter might be giving you a false reading. So, that could explain the difference too. Now, when dead, most narrowbands read a constant 450mV.
Second, a narrowband when working does not show as a constant voltage, but rather a rapidly changing AC voltage between 0 and 1 Volt. The reading you get with a DC meter (or tool) is the RMS (average) voltage of the AC signal. Good meters often advertise "True RMS", but a basic meter might be giving you a false reading. So, that could explain the difference too. Now, when dead, most narrowbands read a constant 450mV.
