E67 Open Loop Idle?

[JAY4SPEED]

I'm attempting to get my truck to OL idle to control idle AFR via the PE table with a larger camshaft (230/242 .600 110lsa. Engine is a stroked LS3 6.8L) and to keep fuel trims from skewing AFR from the cam overlap. Right now I'm setup for speed denisty while tuning the VVE table so the MAF is disabled.

From what I understand there are 3 qualifiers that needed to be changed. I've lowered the RPM (B0155) and MAP (B0157) qualifiers and have altered the throttle threshold to 0 from 0 to 1024 RPM (B0156). I'm not quite sure what to do with the hysteresis for RPM, MAP and Throttle (B0159, B0160, B0161 respectively) and what they would need to be changed to. I've also changed PE mode commanded fuel (B3618) to command 1.00 EQ Ratio from 0-1024 cells.

I'm trying to obtain a steady commanded AFR without +/- LT trims to start my way down the idle tuning path. Upon intial flash, the truck will obtain OL-Drive at idle but the commanded AFR is way low around 12.24 (I have no idea why it's commanding that low) and the truck will stall out when going OL at idle. To restart, I have to feather the throttle manually and let it settle back down to idle and once again when it goes OL-Drive in idle, the truck will stall out with a crazy low commanded AFR. After going through this maybe two or three times, the truck will then start and idle, but stay in CL. Another thing I noticed at OL idle (and CL idle for that matter) it's indicating that it's still applying LT trims when in OL-Drive at idle before it stalls out or if it stays running in CL. I can clear the trims but they will return again before it stalls out.

Or would adjusting B1103, B1104 be a better approach?

I'm looking for some ideas on something that I might be missing in the setup for OL idle. I'll have to try to get a log of it doing this. I'll post the tune below for now. Any ideas or guidance is appreciated. Thanks!

Jay

[gmh308]

I'm attempting to get my truck to OL idle to control idle AFR via the PE table with a larger camshaft (230/242 .600 110lsa. Engine is a stroked LS3 6.8L) and to keep fuel trims from skewing AFR from the cam overlap. Right now I'm setup for speed denisty while tuning the VVE table so the MAF is disabled.

From what I understand there are 3 qualifiers that needed to be changed. I've lowered the RPM (B0155) and MAP (B0157) qualifiers and have altered the throttle threshold to 0 from 0 to 1024 RPM (B0156). I'm not quite sure what to do with the hysteresis for RPM, MAP and Throttle (B0159, B0160, B0161 respectively) and what they would need to be changed to. I've also changed PE mode commanded fuel (B3618) to command 1.00 EQ Ratio from 0-1024 cells.

I'm trying to obtain a steady commanded AFR without +/- LT trims to start my way down the idle tuning path. Upon intial flash, the truck will obtain OL-Drive at idle but the commanded AFR is way low around 12.24 (I have no idea why it's commanding that low) and the truck will stall out when going OL at idle. To restart, I have to feather the throttle manually and let it settle back down to idle and once again when it goes OL-Drive in idle, the truck will stall out with a crazy low commanded AFR. After going through this maybe two or three times, the truck will then start and idle, but stay in CL. Another thing I noticed at OL idle (and CL idle for that matter) it's indicating that it's still applying LT trims when in OL-Drive at idle before it stalls out or if it stays running in CL. I can clear the trims but they will return again before it stalls out.

Or would adjusting B1103, B1104 be a better approach?

I'm looking for some ideas on something that I might be missing in the setup for OL idle. I'll have to try to get a log of it doing this. I'll post the tune below for now. Any ideas or guidance is appreciated. Thanks!

Jay

Take a look at the Idle Sticky - E38 Idle Tuning. E67 is the same.