
Originally Posted by
farmtruc
Those codes aren't as bad as it sounds. Those codes are caused by a vac leak or a bad o2 sensor. Or, it could possibly be a tune, but if it just started happening... you didn't mention how long it's been doing this.
Those codes will not set during a wot run, more than likely, at wot it's rich, but like the other guys said, you never know until you check it with a wb.
I command a safe a/f ratio in the calibration, however, commanded and actual a/f ratio are two different things.
Those codes are set during idle and normal driving. For some reason during normal driving the pcm can't add enough fuel to keep the ltrims in line. SO, once they hit their max limit, the pcm sets this code.
If extra air is entering the engine that the maf is not detecting, then the pcm can never add enough fuel to compensate. The pcm will over compensate and continue to add fuel to cure the false lean condition, but of course it never will as long as there is a leak somewhere, pretty much the same thing with a false reading from the o2 to the pcm, in closed loop.
A bad o2 sensor is at fault, most of the time, when a customer complains about his truck running fine during startup, then after about 2mins (when closed loop happens) the truck runs bad.
Send me an email or call us when you get the wb on and let me know what it is during wot, actually during any rpm and boost level.
Hope this info helps, and get your truck up here for a live tune!!!!
ttyl,
allen