At around the 2 minute and 32.5 second mark in my log(12:37:49 pm), I am finished the quarter mile run in my final gear (3rd gear, th400 automatic) and let off the throttle.
At this point directly after letting off the throttle, injector pulse width drops from the WOT 14.2 ms to 2.0 ms, Commanded lambda goes to 1.00 but my wideband reads as rich as 0.83 lambda and my ignition timing goes from 28 degrees (wot) to 46 degrees (off the throttle).
3 seconds after, the wideband levels off to 1.0 lambda and the narrowband o2 sensors accordingly drop in voltage around the same time (so the exhaust is definitely seeing this event)...at this same time the spark finally drops from 46 degrees to 5 degrees.
Is the afr the wideband detects when the throttle is released, simply a reality of the remaining fuel after the fuel injectors sprayed their last 14.2 ms WOT burst?
If this is the case, why does my timing spike so high despite the cylinder airmass reading 0.04 grams (same reading at 46 degrees and 5 degrees advanced ) after letting off the throttle?
Is it perhaps transitioning/scaling between the lowest cylinder air mass of 0.08 g and the associated timing of 38* and a threshold of the lowest possible timing figure that's not in the timing table?
This is a 2005 6.0 lq4 with a btr stage 2 cam. p59 ecu, 36 lb flex fuel injectors. Thanks
Reply With Quote
Originally Posted by dermotw
