I keep getting code 44 durring the KOER test. One of the definitions in the manual states that the Oxygen sensor signal indicates Rich - Excessive fuel, Restrictive air intake - or - Inoperative Thermactor System. And another one states Thermactor air system fault.

I had just replaced the o2 sensor last night hopeing that this would get rid of this code. But it did not. EGR valve is two years old and not even 6,000 miles on it. The engine itself has about 4,500 miles on it now.

The engine runs fine and it drives fine. Until I try to get it above 3,000 rpms. At that point the engine starts spuddering, like it's sucking air or missing. I have been using 87 octane fuel. But now, with all the mods that I have done already to my rig,

1) Should I switch to 91 octane?
2) Should I get a new computer?
3) Or Should I add a chip or programmer?

Basically the only 3 mods that I haven't done yet is a set of headers, a chip or programmer, and a complete ignition upgrade(I do have the MSD coil though). I have done pretty much every thing else. I installed Edelbrock intake manifols and throttle body, K & N air filter system, a mild cam, rebuilt motor bored .30 over, Flowmaster after cat with dual output, rebuilt the tranny twice, rebuilt the transfer case, and rebuilt both deferrentials with limited slip and 4.10 gear ratio. This weekend I am going to try to see if there is a low voltage in the wiring for the fuel pump sytem. At one point, last week, I did pull a code of 95 which is Fuel pump secondary circuit fault. But this code has not come up again since. The fuel pump is new. Just replaced it when I started to have this problem.
Any help or suggestions would be greatly apreciated.
Thanks
Kimball

 

All those changes, especially the cam, won't work well with speed density because the computer cannot adjust the air/fuel ratio based on air flow changes. Octane won't make a difference with those codes.

Question, before I go any futher, did you clear codes after the O2 sensor replacement?

 

Thanks for the reply Ken
Yes, I did clear the codes after replacing the sensor.
For every part that I had replaced, in the past two weeks due to codes showing up, I had cleared the codes each time.

 

I wanted to add that every thing was running great, with my current set-up with all the mods, until two or three weeks ago. When engine cut out all of a sudden. After scratching my head for about 5 minutes I was able to start it up(???), and then 40 miles later engine dies again. Had to be towed. That is when I replaced the fuel pump and ignition module. It started right up but I couldn't get it above 2,500 rpms without spuddering. That's when I started to pull codes. The last one, code 44, I still have not been able to figure out yet.
I allmost forgot, last night I accually received codes 45 and 46 twice. I kept on re-testing to see if it's consistent. The only one that is consistent is code 44. I get this just about every time.
Thank you
Kimball

 

Hmmmm... the suddeness leads me to believe you have a short somewhere.