Fuel Trims Disabled?!?!
Fuel Trims Disabled?!?! I've got a buddy with a 408 in a '98 Z. He was complaining about fouling out o2 sensors constantly. Connected the Tech2 and found that they are very slow switching but something else is I noticed the short and long term fuel trims read 0 all the time, even when you bump the throttle nothing happens, I scrolled down on the scanner and it said that the fuel trim learning was disabled. I've never seen/heard anybody else running across this and can't find anything else different from this tune to anybody else's that might do that. Any ideas?!?!?! Thanks guys!!!!!!! 
I didn't get a log on the car just watched it with the Tech2 while cruising around and noticed it. Thought you guys might have seen it before and could tell me what you did to enable it....Frost, you think it is possible the o2s could be causing this? I've seen them set codes and basically quit reading but I haven't ever payed attention to whether it disabled fuel trims or not.
sure have seen it lots; clear the O2 codes with the car up to operating temp. If things are ok (no code rapidly re-set) then it should return to CL unless commanded otherwise in his tune.
Cleared codes (p0300) and drove through two complete cycles no codes set and fuel trims still showing disabled. I don't think the o2s ever through a code they just seem to be reading really slow, still bouncing from 100mV to 800mV, I thought that could be related to the fuel trims not adjusting. So do you think that it is something in his tune? Don't know who tuned it before it came to me so do you know a few things I can check? Like I said, no codes other than p0300 (nothing consistent), o2s still switching full sweep, and it is going into closed loop.
