WOT = 4 O2 sensor low voltage.
Thread Starter
Teching In
Joined: Jun 2015
Posts: 16
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WOT = 4 O2 sensor low voltage. Hello all!
Brand new to the forums and to the LS world. Had a 1996 Z28 Camaro and decided to upgrade to a 1998 SS Camaro. Has the SLP lid, ram air, LM1 exhaust and SLP headers on it.
Bought it knowing it had a bad O2 (behind the second cat), replaced it and drove it around and it was fine. Decided to WOT it today and a code threw at around 85MPH. No noticeable power loss, though I'm new to LS so maybe there was power loss...nothing I could feel.
Anyways, get home and I read the codes, 4 codes all saying each O2 had low voltage. I've been looking around and read that a bunch of different things could be wrong with it. Unfortunately all of these never led to any solutions so I was hoping someone here could help me with what to look for. From what I can tell the car has never been properly tuned. I am in contact with the prior owner of F-body Central and he says he can give me a good tune for 300 bucks.
Before I want to do any of that, though, I want to alleviate this problem.
Any help would be appreciated
Thanks!
Brand new to the forums and to the LS world. Had a 1996 Z28 Camaro and decided to upgrade to a 1998 SS Camaro. Has the SLP lid, ram air, LM1 exhaust and SLP headers on it.
Bought it knowing it had a bad O2 (behind the second cat), replaced it and drove it around and it was fine. Decided to WOT it today and a code threw at around 85MPH. No noticeable power loss, though I'm new to LS so maybe there was power loss...nothing I could feel.
Anyways, get home and I read the codes, 4 codes all saying each O2 had low voltage. I've been looking around and read that a bunch of different things could be wrong with it. Unfortunately all of these never led to any solutions so I was hoping someone here could help me with what to look for. From what I can tell the car has never been properly tuned. I am in contact with the prior owner of F-body Central and he says he can give me a good tune for 300 bucks.
Before I want to do any of that, though, I want to alleviate this problem.
Any help would be appreciated
Thanks!
Unless there is something wrong with the sensors or the power to them I would expect them to read low voltage at WOT. Not enough to trigger a CEL but still low. When you go WOT the engine enters into PE(power enrichment). During PE the engine shuts off the fuel trims and ignores the O2's altogether. It uses only the MAF sensor. This is of course on a stock PCM OS that has not been modified to disable the MAF or MAP. During normal driving the PCM uses a hybrid MAP/MAF setup in conjunction with what the O2's are reading to try to better adjust to atmospheric changes.
When you go WOT the PCM pumps in enough fuel (supposed to) to achieve roughly a 12.7-13.0AFR. The narrowband O2's do not work in this area.
I'd look into voltage supply issues. All 4 are supplied by the same source. Pink wire switched ignition. You could have a bad sensor that is causing enough draw to induce a voltage drop.
When you go WOT the PCM pumps in enough fuel (supposed to) to achieve roughly a 12.7-13.0AFR. The narrowband O2's do not work in this area.
I'd look into voltage supply issues. All 4 are supplied by the same source. Pink wire switched ignition. You could have a bad sensor that is causing enough draw to induce a voltage drop.
Unless there is something wrong with the sensors or the power to them I would expect them to read low voltage at WOT. Not enough to trigger a CEL but still low. When you go WOT the engine enters into PE(power enrichment). During PE the engine shuts off the fuel trims and ignores the O2's altogether. It uses only the MAF sensor. This is of course on a stock PCM OS that has not been modified to disable the MAF or MAP. During normal driving the PCM uses a hybrid MAP/MAF setup in conjunction with what the O2's are reading to try to better adjust to atmospheric changes.
When you go WOT the PCM pumps in enough fuel (supposed to) to achieve roughly a 12.7-13.0AFR. The narrowband O2's do not work in this area.
I'd look into voltage supply issues. All 4 are supplied by the same source. Pink wire switched ignition. You could have a bad sensor that is causing enough draw to induce a voltage drop.
When you go WOT the PCM pumps in enough fuel (supposed to) to achieve roughly a 12.7-13.0AFR. The narrowband O2's do not work in this area.
I'd look into voltage supply issues. All 4 are supplied by the same source. Pink wire switched ignition. You could have a bad sensor that is causing enough draw to induce a voltage drop.
http://www.gearchatter.com/viewtopic8755.php
Misfiring (excess plug gap, single crusty injector) can
spoof sensors to make a low output. All four discounts
the single-injector theory, points to an overall lean or
some electrical fault. Electrical fault ought to bother
more sensors than just these.
Fuel pressure drop under load might be about the
fuel pump and plumbing, maybe the old car had a
lesser delivery capability than you need or maybe
the fuel filter is as old as the chassis, or maybe
the wiring & connector resistance is limiting the
big end fuel pressure*flow. You just have to chase
it down to a provable cause.
spoof sensors to make a low output. All four discounts
the single-injector theory, points to an overall lean or
some electrical fault. Electrical fault ought to bother
more sensors than just these.
Fuel pressure drop under load might be about the
fuel pump and plumbing, maybe the old car had a
lesser delivery capability than you need or maybe
the fuel filter is as old as the chassis, or maybe
the wiring & connector resistance is limiting the
big end fuel pressure*flow. You just have to chase
it down to a provable cause.
At WOT the O2 Low Voltage diagnostic does look at O2 sensor voltage. And O2 sensors generally go to somewhere in the 8xx-9xx mv range at WOT. Look at criteria 2. Conditions for running and setting the DTC.
http://www.gearchatter.com/viewtopic8755.php
http://www.gearchatter.com/viewtopic8755.php
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WOT = 4 O2 sensor low voltage. Did you take the MAF apart and use a q-tip as well? Geoff showed me this one time when on the dyno cause he suspected my MAF was dirty. I told him I had literally JUST cleaned it.
That's when he laughed and removed it showed me what I missed by just spraying it
That's when he laughed and removed it showed me what I missed by just spraying it
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Thread Starter
Teching In
Joined: Jun 2015
Posts: 16
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Nope I haven't done that I just sprayed everything I could see! Tomorrow when I have it off again I will use a Q-tip.
Registered User
Joined: Jun 2022
Posts: 1
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Hello all!
Brand new to the forums and to the LS world. Had a 1996 Z28 Camaro and decided to upgrade to a 1998 SS Camaro. Has the SLP lid, ram air, LM1 exhaust and SLP headers on it.
Bought it knowing it had a bad O2 (behind the second cat), replaced it and drove it around and it was fine. Decided to WOT it today and a code threw at around 85MPH. No noticeable power loss, though I'm new to LS so maybe there was power loss...nothing I could feel.
Anyways, get home and I read the codes, 4 codes all saying each O2 had low voltage. I've been looking around and read that a bunch of different things could be wrong with it. Unfortunately all of these never led to any solutions so I was hoping someone here could help me with what to look for. From what I can tell the car has never been properly tuned. I am in contact with the prior owner of F-body Central and he says he can give me a good tune for 300 bucks.
Before I want to do any of that, though, I want to alleviate this problem.
Any help would be appreciated
Thanks!
Brand new to the forums and to the LS world. Had a 1996 Z28 Camaro and decided to upgrade to a 1998 SS Camaro. Has the SLP lid, ram air, LM1 exhaust and SLP headers on it.
Bought it knowing it had a bad O2 (behind the second cat), replaced it and drove it around and it was fine. Decided to WOT it today and a code threw at around 85MPH. No noticeable power loss, though I'm new to LS so maybe there was power loss...nothing I could feel.
Anyways, get home and I read the codes, 4 codes all saying each O2 had low voltage. I've been looking around and read that a bunch of different things could be wrong with it. Unfortunately all of these never led to any solutions so I was hoping someone here could help me with what to look for. From what I can tell the car has never been properly tuned. I am in contact with the prior owner of F-body Central and he says he can give me a good tune for 300 bucks.
Before I want to do any of that, though, I want to alleviate this problem.
Any help would be appreciated
Thanks!
did you figure out the issue? i’m having basically the same problem
