camaro's dying on me. throwing codes "banks 1 and 2 too lean" i'm thinking it's a sensor. or worse the computer(probably not). well something is telling the computer to max out the injectors. after i start it, i watch both driver and passenger banks climb and compensate to 50% rich(can't go any higher on my scanner) short and long term. of course the car dies at that point. restart and it does it again. hit the gas, it dies instantly. so much fuel it's stalling out. i cleaned the mass air sensor. next im going to clean the iac and tps. maybe get a new coil. fuel pressure is good. don't think theres i vacumn or exhaust leak. any ideas? it just happened all of a sudden friday. can o2's instantly go out?

 

The long terms are limited to +25% (160 max BLM / 128 = 1.25). Are you sure you're seeing +50% on long terms?

Since you have a scanner on it, what are the O2 sensors reading? What does the MAF read at idle (should be 6 - 10gps)? What is the MAP sensor reading (should be around 10"Hg or 35kPa)? What does the TPS sensor read at idle (should be in the range of 0.20-0.80V)?

 

+50% short term for sure. I don't think I checked long term before It died. Both front O2's are jumping between .100V and .800V normal right? The pass. side rear O2 holds @ .600V, but the drivers rear is @ .070V. MAP between 7-8"hg. TPS= .5V, measured at plug right? My scanner's an older Autoxray, can't measure MAF. Though I did clean it after I got it home. Just drove to Checkers and back watching scanner. Everything fine. Let it idle for 20 mins, and it didn't act up. 119,000 miles on factory O2's. I'm thinking front O2's myself. But why is the problem intermitent and start all of the sudden?

 

Any thoughts Fred?

 

did you try it in open loop?

 

I didn't check it in open loop. The car was driven around all day, and was warmed up, when it started doing it. That's when I scanned it. It's been fine since. As soon as it starts stalling out again, I'll see what it's doing right after start up.

 

The after-cat sensor voltages look odd. They should be cycling like the fornt ones, just over a narrower range. But the rear O2's don't control anything, they just report on the condition of the cats.

But the .070V on the driver's side after-cat may indicate the O2 sensor on that side is slightly "off" and allowing the engine to run a bit leaner on that side than it should. You could try swapping the pre-cat sensors side-to-side to see if the odd after-cat O2 reading follows the sensor or stays with the cat.