I have done searches and have found some information about trouble code 44 (Left O2 sensor - lean condition) but I'm not sure why I'm getting this code. My mods are in the sig. I've had headers for about 10 months now and the problem has only developed in the last month. I get stumble when I have the gear in 1, 2, or 3, but haven't noticed it in drive. I floored it around 90 on the highway a few days ago and when the RPMs got around 4100 in 3rd, it started to drop to below 4000. Injuneer, I've seen that you have replied to a few other posts about this code, so could you help me out with this?

Thanks in advance,
Steve

 

The code sets when the O2 sensor is indicating a lean condition, and the long term fuel corrections (BLM's) max out at 160, and still don't cure what the O2 sensors are indicating is a lean condition.

There are two possibilites....

A. It really is running lean. In that case, you need to get a scanner on it and look at the BLM's for both the left and right banks, at idle, part load and at WOT. That will tell you whether you have a problem that is affecting one side of the engine or both. The right side may be running lean too, but the BLM's may not be high enough to set the code. The misfires under heavy load, and the fact they are moving lower in the RPM band might be indicating a weak fuel pump, for example.

B. Its a "false" lean condtion. The three most likely causes are header leaks before the O2 sensors, misfires and bad O2 sensor or wiring. Any of those can trick the PCM into thinking the bank is running lean, and cause it to add fuel you don't need. The fact that you are feeling a misfire under load, and the point at which that misfire occurs tells me you may have a problem with burned wires, fouled plugs, weak coil, etc, that is gradually getting worse. Here again, you need to look at both banks of the engine, to see if its a problem strictly with the left bank, or if there are signs of problems on the right side as well.

 

Thanks for the quick response. I have noticed that on the +1 primary on the driver side it is a bit black around the slip-fit. I'll take a pic of it tomorrow if I have time. I'm not sure what to do about that if it is the problem.... weld it? Also, where can I get a scanner for my car or get my car scanned for BLM? Would a bad fuel pump lower my MPG, because I've been getting about 15-16 mpg lately.

Thank you very much,
Steve