I'm a gen5 4cyl guy, not getting very far with a problem. So I'm trying here for what I think may be a gen 5 problem for multiple platforms. I have gotten a lot of valuable tuning info from gen4/gen5 threads for my 4cyl so I thought why not.
I am having a fueling issue when going to wot before PE mode kicks in. Basically I go to WOT and fueling dips really quick to an unknown 13.45 afr. for a split sec. Then back to stoich for about a half a sec. Then back to the unknown 13.45 afr. for about a sec. Then back to stoich for about a sec...... then PE mode finally kicks in (~12.25 afr). That last jump from the unknown 13.49 afr to stoich is where a large power hit comes from as you can see by the afr and torque traces on the pic below.
I have gone through all PE tables and this isn't related to those. It has to be a parameter under the o2 sensor switching tables or open loop/closed loop fueling tables. I just cannot figure out which and where? Any ideas, thoughts, or input is greatly appreciated.
I read about gen4 and gen5 v8 slow o2 switching causing a similar issue, but cannot find that thread again. It got me thinking this could be related to my problem? Just not sure where to start with GM slow 02 switching? And I am watching my Fuel System Status pid which also shows it going back and forth between close and open loop fueling. So I'm also thinking it could be related to something with OL/CL control or multipliers?
I am slightly new to GM tuning, coming from Chrysler tuning which isn't even comparable to this. So I apologize if this is an obvious GM thing to some. I haven't had much luck diagnosing/investigating the problem.
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