O2 problem, weird!
11-21-2003, 12:27 AM
#1
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Join Date: Jul 1998
Location: Los Angeles, CA
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O2 problem, weird!
I was commuting tonight and suddenly the car starts to miss heavily at low rpm, then the engine light came on.
I pulled over and took the scanner out of the trunk; I got a code saying that one of the sensors reported a lean value, so I assumed that the extension got disconnected / burnt by the headers, but it got weirder:
one of the bank has a 108 blm, the other one has a 160 blm! they're both maxed out in opposite directions!
then one sensor reports a steady 2mv while the other goes around 100mv!
to rule fuel / ignition issues, I did a high rpm pull (so that it doesn't use the o2 sensors for feedback) and the car ran great, so I am assuming the problem is electrical, but I can't find what would affect both sensors at once...
I tried to reset the computer to rule out any weirdness there, but nothing different.
any idea?
I pulled over and took the scanner out of the trunk; I got a code saying that one of the sensors reported a lean value, so I assumed that the extension got disconnected / burnt by the headers, but it got weirder:
one of the bank has a 108 blm, the other one has a 160 blm! they're both maxed out in opposite directions!
then one sensor reports a steady 2mv while the other goes around 100mv!
to rule fuel / ignition issues, I did a high rpm pull (so that it doesn't use the o2 sensors for feedback) and the car ran great, so I am assuming the problem is electrical, but I can't find what would affect both sensors at once...
I tried to reset the computer to rule out any weirdness there, but nothing different.
any idea?
11-21-2003, 08:46 AM
#2
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Join Date: Nov 2003
Posts: 17
I have a similar problem going on where both of my O2s report flat 451mV about 80% while driving....it will work correctly at WOT about 20% of the time and then return to flat 451mV soon after or during. I just replaced one sensor for testing purposes and I don't have any headers or anything. Our problem may be related, though.
Not sure if you know this already, but 2mV and 100mV are far from opposite sides of the scale as far as O2 sensors go...I have seen them go from single digits to 900+. Are your sensor(s) going bad perhaps? Or is the reading completely static?
Not sure if you know this already, but 2mV and 100mV are far from opposite sides of the scale as far as O2 sensors go...I have seen them go from single digits to 900+. Are your sensor(s) going bad perhaps? Or is the reading completely static?
Last edited by 93CamaroDude; 11-21-2003 at 08:54 AM.
11-21-2003, 11:07 AM
#3
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Location: Los Angeles, CA
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I was talking about the BLMs going to opposite directions; I'm not sure why it happens, that is totally weird.
the 2mv sensor seems frozen, the other one moves a little bit around 100mv; it seems like they both have a bad ground or something like that happened. Because it happens on both sensors at once, it almost rules out the sensor itself (what are the chances of them going bad instantly at the same time?)
I have another idea: these sensors are heated, so what if the power to the heater element (which almost certainly comes from a common line under the hood) doesn't work anymore? I assume they were reading 450mv when cold, but I don't remember
Anybody else has seen something similar?
the 2mv sensor seems frozen, the other one moves a little bit around 100mv; it seems like they both have a bad ground or something like that happened. Because it happens on both sensors at once, it almost rules out the sensor itself (what are the chances of them going bad instantly at the same time?)
I have another idea: these sensors are heated, so what if the power to the heater element (which almost certainly comes from a common line under the hood) doesn't work anymore? I assume they were reading 450mv when cold, but I don't remember
Anybody else has seen something similar?
11-24-2003, 12:04 PM
#4
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Posts: 17
That's actually an interesting theory...I really have no idea how they work from a technical standpoint. The fact that my sensors are run off a single wire ('93) would lead me to believe that that wire is not connecting properly or something. Again, the fact that the two stop functioning at the same time on both of our cars really creates quite a mystery. I haven't found anyone yet who can really explain it. I still have to go out and do a continuity test on the wires. Anything new on your case?
11-24-2003, 10:22 PM
#5
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Location: Los Angeles, CA
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on the advance tech forum, one theory was that the ignition is failing so the o2 read very lean on both sides.
I need to do some more tests but I haven't hads a chance to touch the car last week-end. I'll do it this week.
I need to do some more tests but I haven't hads a chance to touch the car last week-end. I'll do it this week.
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