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i've replaced the o2 sensor with a stock gm o2 sensor.. the o2 voltage still read lean on the computer but didin't throw any codes.. so i replaced it with a accel heated o2 sensor.. its still doing the same thing.

i can richen the car up to a point where you could faint standing behind it and the o2 voltage still doesn't get above 0.400mv blms stay around 140/150

could it be a bad ecm? or something els i'm stumped on this one

blue86iroc

iTrader: (2)

The switching-style O2 sensors aren't really a great way for determining air/fuel ratio or tuning the BLM values. They're only designed to let the ECM know if it's richer or leaner than 14.7:1, but not by how much. The narrow-band O2 sensor readings aren't constant between vehicles, either. It depends on various engine components and is (generally) unique to each car. The O2 sensor is indicating a lean condition in relation to your BLM readings, but I wouldn't think that -0.500mV would be an increase of 22 counts in the BLM (~0.900mV/128 BLM nominal).

Are you sure that the O2 sensor is set for the correct air/fuel ratio? You want it to be at 14.7:1, unless you've changed something in the EPROM.

You may want to post this over on the DIY PROM board, too.

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ok when the blms are around 150/160 the car is pig rich i mean you will literaly faint if you stand behind the car.. i keept increasing the maf tables and the blms are not comming down.

its like a neverending lean condition that doesnt exist.. i bought a delco o2 sensor that didnt help so i doubt the new sensor is off its doing the same thing the old one did..

heres the sensor i bought

http://www.jegs.com/cgi-bin/ncommerc...84&prmenbr=361

i thought the o2 sensor may have just not been getting hot enough

air fuel is set at the default 14:7.3.. car runs better with the o2 sensor unplugged because it actually uses my fuel settings..

blue86iroc

iTrader: (2)

Well, if the BLMs are over 128, the ECM thinks that the engine is running lean, so it's trying to add fuel. Since you're approaching the upper BLM limit of 160, the car is (supposedly) terribly lean... so it's (incorrectly) adding large amounts of fuel for correction. Maybe too many things were changed on the MAF tables and now everything is out of whack... try restoring the factory MAF table values and unplugging the battery for twenty minutes to clear any learned settings. See if that helps. Or, load up a factory calibration and see if the BLMs return to normal.

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i tried unplugging the battary and running the stock ANZA bin.. still did the exat same thing.. for some reason the ecm isnt reading the voltage correctly from the o2 sensor.. the o2 voltage drops to 0.12mv at time which is insane.. with the o2 sensor unplugged the o2 voltage reads around .450mv once you plug it in it usually hangs around .200 .300mv


edit: oh i forgot to add this is a heavily modified setup.. 383 superram 30lb injectors etc.. running a stock calibration makes it run even worse..

blue86iroc

iTrader: (2)

Under those circumstances, I'm sure that motor is very unhappy with the factory programming .

There may be a way to check the operation of the oxygen sensor with a multimeter, but I'm not sure of the process. I think that it just adds resistance to the line, which in turn causes variations in the voltage at different O2 levels.

You could be correct about a failed ECM. If you have a spare, I'd suggest trying that. Maybe some other members can help you out, too.

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ugh.. the collector has a big exhaust leak.. dont ask me how i havent heard it before.. "really loud exhaust"... that would cause the o2 to spike? or read lean? because its catching the oxygen from the leak?

blue86iroc

iTrader: (2)

It could be possible; I'm not sure. Regardless, it's a problem in the same category as the oxygen sensor... try fixing the leak and see what happens.