that de accel popping sound that nobody likes... I want it! DFCO

[zchrisz1986]

hey guys! i for the most part have my car tuned pretty well, i'm running a 2002 tahoe flex fuel tune on a 6.0 lq9 with gm hotcam and longtube headers.

Tune currently in maf only mode.

i enabled dfco and there is no popping what so ever letting off the gas. i did play with the map entry / exit table i raised some map values and on testing there was no popping but there was one LOUD pop that sounded like a backfire. i then copied settings from a camaro manual tune and it instantly goes in to DFCO with no popping what so ever. advice?

tune attached.

[lukearmstrong1990]

mafless cam base.hpt

see attached DFCO settings. look at clutch transition tables also.

if you want the pop on decal then use the RPM enable to get it cutting fuel sooner.

exhaust design can also play a large roll in decal note.

typically is the lean condition that creates the popping sound on decel

[zchrisz1986]

i tried your settings, i did not have any loud backfires, but no crackle or pop. slight burble on dfco exit

[JD_AMG]

I just recently figured this one out myself. You don't need DFCO, you can turn if off if you want. All you need to do is lower your ignition timing in the lower cylinder air mass cells (0.08 G) where engine braking occurs to under ~10* roughly. Do it in your high octane spark table and your idle spark table. Should gurgle and crackle good when engine braking.

[zchrisz1986]

i'll give it a try, i'm running the stock timing table for the LQ9 the timing in that area is high 30's and 40's