Please critique tune and offer assistance

[evolmotorsprt]

Hi all, I'd like some help and critiquing on my tune. I have the VE and MAF dialed (both with a wideband), and have the idle rock solid on my setup. When I come to a stop the RPMs fall easily back into idle. It runs great at part and full throttle. In all I'm very satisfied with what I've been able to put together. Heck, I even have the O2s switching well at idle. I'm getting into the extreme fine tuning.

The last issue that I haven't been able to fix is the good old bucking between 1k-1.7k RPMs, with light throttle at slow speeds and cruising along at 40MPH in 4th gear. I've read several threads and tried many different methods to fix this bucking:

Matched all appropriate zones in timing tables.
Raised and lowered timing in above zones.
Lowered proportional fueling values.
Disabled proportional idle.
Messed with O2 switching points.
Richened and leaned VE and MAF in the bucking zones.
Zeroed throttle cracker.
Made sure MAF, VE, BRAF are as solid as I can get them.
Messed with EOIT. <- Over (normal = 6) drivability at low RPM sucks for my car

Here are my mods:
42# Deatchwerks Injectors - with good data
TSP 228R 112LSA
Ported LS6 heads - 11.15:1 compression
Ported Fast 92
LS2 90mm TB
LG Superpros
Vararam
Stock Short Block
etc...
Pretty Basic Stuff

Here's my tune. If there's anything you'd like to see logged I can do that. I'd really appreciate any advice you can give. Thanks.

My 2002 Corvette 6MT Base Tune - getting closer.hpt
19-03-24 13-43-46.hpl
GEN III Basic.Layout.xml

[evolmotorsprt]

So after looking at my log I noticed something else interesting. I don't know if this is from spark smoothing or the MBT table, but I'm getting spark much higher than I should at 1400RPM. Should I edit the MBT table? Could this be DFCO related? Check out the pics below:
Scan.PNG
Spark Tables.PNG

[cobaltssoverbooster]

i dont see any other spark modifiers active at that position you captured. this is according to the tune file in the first post. I would give a reduction of MBT a try. Personally i have not altered this table much but in the 4 cyl ecu's mbt plays a role in the urgency obtaining commanded values. if this is overshot by a large amount then there are cases where the TB or ignition would be erratic and in some cases cause higher than commanded ignition due to what i observed to be an overshoot. the 4 cylinder ecus are pretty heavy on torque modeling which is not so much the case for these ecus. because of this im unshure how effective the mbt changes will be. it is worth a shot though.

just a note, your ltft during the snapshot are ~11% plus an average of ~2% on the short term in the same direction. have you tried reducing fuel error to annotate the ignition effects? these ecu's behave differently due to cylinder fuel load which is the only reason i bring it up.

[evolmotorsprt]

i dont see any other spark modifiers active at that position you captured. this is according to the tune file in the first post. I would give a reduction of MBT a try. Personally i have not altered this table much but in the 4 cyl ecu's mbt plays a role in the urgency obtaining commanded values. if this is overshot by a large amount then there are cases where the TB or ignition would be erratic and in some cases cause higher than commanded ignition due to what i observed to be an overshoot. the 4 cylinder ecus are pretty heavy on torque modeling which is not so much the case for these ecus. because of this im unshure how effective the mbt changes will be. it is worth a shot though.

just a note, your ltft during the snapshot are ~11% plus an average of ~2% on the short term in the same direction. have you tried reducing fuel error to annotate the ignition effects? these ecu's behave differently due to cylinder fuel load which is the only reason i bring it up.

Thanks for the input, I'll give the MBT table a shot. WRT the fuel trims, the area you talked about is in the decel/off throttle region. Idle in my car is ~35-40kPa. With the cam overlap I thought adding too much fuel to this area would make it overly rich because of the surplus oxygen. I have though about increasing the MAP threshold (20kPa currently) for when the LTFTs are active and hard coding the fueling in the <35kPA decel zones. I'm definitely open to adding more fuel to these regions, so I'll do a few experiments.

[Lakegoat]

At key on , engine off, your map reads 86kpa. It should read around 98 to 100. The linear and offset in your tune is for a 1 bar GM sensor. Have you changed the map sensor. OR, look at the part number and see what it is.

[evolmotorsprt]

At key on , engine off, your map reads 86kpa. It should read around 98 to 100. The linear and offset in your tune is for a 1 bar GM sensor. Have you changed the map sensor. OR, look at the part number and see what it is.

I appreciate your help. I probably should have added I live at 4200' above sea level.

[cobaltssoverbooster]

I live at 4250 and it reads roughly 86-87 depending on the day.

[Area47]

MBT has more to do with fueling than timing in how it's setup in the ecm itself.

[evolmotorsprt]

just a note, your ltft during the snapshot are ~11% plus an average of ~2% on the short term in the same direction. have you tried reducing fuel error to annotate the ignition effects? these ecu's behave differently due to cylinder fuel load which is the only reason i bring it up.

So I added some fuel to those low MAP decel zones in the VE and MAF tables. I also pulled a little timing out in those areas as well. I decided not to mess with MBT, and when I logged today I wasn't seeing those high advance numbers. I was able to reduce the bucking to a very minor stutter that wouldn't be noticed if you weren't paying attention. I'd like to say thanks, because I definitely learned a little more fuel in the system can calm down the reaction and behavior of the engine. I can now let the engine lug around in a parking lot around 1k with no issues. Cheers!

[cobaltssoverbooster]

ive noticed fuel load has a huge role in eliminating erratic results. good to hear you got it solved.