Hi, I've been having some trouble with nailing down a 2bar SD tune for my Camaro. The car has a 383 LT1 with a Procharger D1 and is running 2bar SD in open loop. The biggest problem I'm trying to solve are lean transients on tip-out, although tip-in seems decent. The AFR consistently spikes to full lean on my wideband between shifts (stick car), even after adding a ton of fuel to the corresponding VE cells. Those areas of the VE table are super rich during steady state conditions despite the spikes. This seems to happen even without the car going into DFCO. The driveability isn't too bad with the current tune, but I'm afraid of lean spikes potentially causing knock after high RPM shifts.
Things I've tried playing with:
-126EF Min Transient Fuel Mass -- I had issues with this in an earlier thread where I couldn't get the logged bpw under 1.24ms with these Siemens Deka 80 injectors. I've tried several values from 2mg to 3.75mg with little change to the spikes since initially lowering it from stock. At 4mg, the spikes were certainly less pronounced and shorter in duration, although the throttle response was somewhat sluggish.
-SD airflow patch -- currently enabled
-124B4 Derivative Gain -- Have tried stock Z28, stock Y-body, and currently am using Y-body +20%
-124C3 Cyl Correction vs TPS -- Have slightly boosted all values at 12% TPS and up by +20%
-12021 Delta TPS threshold -- pushing this up higher than the delta TPS between shifts really killed the tip-in, so I set it back to 3%
-12413 Ramp out if lower than 12021 -- haven't changed this from the stock setting of 2, but should I? Figured my issue was a ramp-in related one
-12414 Ramp in if higher than 12021 -- don't remember this affecting much, I think I tried 0.40, 3.5, and currently have it set at 1.1
-126F5 Fuel boiling time -- rescaled for 2bar
-12848 Cyl wall impact factor -- rescaled for 2bar
-126AF High Baro -- Was set to all 1's in an early version of the tune in an attempt to sidestep baro update. Only goes down to 65kpa, so probably not of much use.
-Low injector pulse adders -- Was suspicious of Siemens' data so I recently tried doubling them after seeing logged bpw drop to as little as 0.82ms, but the lean spike still pegs the wideband
Any ideas on what I should try next or how to work around the spikes? I thought about pulling loads of timing in the bottom column of the spark table to create a pseudo DFCO, but the table only goes down to 25kpa and unfortunately the MAP dips on negative TPS transients are all around 20kpa.
Here are some pics of me testing throttle response at idle while changing a few parameters: https://imgur.com/a/VqYp50I
Here's a pic from the most recent tune revision where I really fattened up the low MAP VE cells. You can see it get very fat at low TPS %, but there are still lean spikes. There is a pulse width difference in the logs, usually 20% or less between the spikes and steady state which doesn't seem to account for the wideband activity.
Copy of the EEhack log can be found here: https://drive.google.com/file/d/1sUM...ew?usp=sharing
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