checking a/f with 02s
03-01-2006, 08:30 PM
#1
checking a/f with 02s How close can you tell your a/f off of your 02s on a stock truck? Would I need to log short term and long term fuel trims? I know its not going to be 100%. A friend has a 04 truck with just cold air intake and exhaust and was curious about his a/f.
03-01-2006, 08:38 PM
#2
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Without a wideband, you can't tell what your AFR is at WOT (open-loop). You can tell what the PCM is commanding and you can see if it is adding in extra fuel, but that's about it. During cruise scenarios (closed-loop), your AFR is going to be 14.63 or there abouts. If it's not, the fuel trims will adjust accordingly so it is there. Chances are, if he's just got a few bolt-ons like intake and exhaust, he's running an AFR close to high 11's or low 12's. The factory programs the PCM's pretty rich from the start. If you were lean during cruise the LTFT's would be added to the WOT fueling as a safety precaution. Hope that helps some....