Tuning in a coast/glide?

L

lotsofmiles

Father of the Van
Dec 4, 2008
3,097
0
0
Michigan
I really like that I can let off the go pedal as I approach an off ramp on the highway and almost come to a complete stop without hitting the brakes.

but...

is there a way to tune out all engine and trans "braking" so that when I let off the go pedal it just coasts?
 
JoshH

JoshH

Daggum farm truck
Staff member
Vendor/Sponsor
Feb 14, 2007
13,712
773
113
Texas!!!
You might try lowering all the downshift points and making the converter unlock when you let off the accelerator pedal.
 
whytry

whytry

New member
Oct 11, 2010
282
0
0
it is locked in normal mode... when your in 6th gear cruising and when you go 100% throttle from 2nd gear and up...
 
L

lotsofmiles

Father of the Van
Dec 4, 2008
3,097
0
0
Michigan
IDK if I've ever done 100% throttle.:rofl: I'm talking about cruising on the eway, normal mode/not towing, probably well under 30% throttle, and let off the go pedal.

I know its not apple to apple comparsion, but the van (99 express 5.7 gas 4l80) seems to coast forever when you let off the gas. espically 20-40mph range. The dmax slows quickly, to almost a stop under same circumstanses/roads.
 
whytry

whytry

New member
Oct 11, 2010
282
0
0
When your cruisin on the eway in normal mode when the truck is in 6th the converter is locked
 
chevyburnout1

chevyburnout1

Fixing it till it breaks
Aug 25, 2008
2,368
1
38
Berthoud, CO
The converter stays locked during coasting until about 45mph if I remember correctly. Then it unlocks and starts downshifting. Maybe you can set 0% throttle on the shifts to keep the tranny up in the higher gears for a while longer.
 
chevyburnout1

chevyburnout1

Fixing it till it breaks
Aug 25, 2008
2,368
1
38
Berthoud, CO
lotsofmiles said:
so, unlock the convertor, but its already unlocked. got it!:roflmao:
Click to expand...

I was just pointing out what speed it unlocks. So basically saying if you set the unlock speed higher at 0% throttle then it may unlock above the 45mph area. And then I mentioned setting the 0% throttle downshift settings to a lot lower mph so as to keep the truck up in the higher gears longer.

Just trying to help out.
 
duratothemax

duratothemax

<--- slippery roads
Aug 28, 2006
7,139
10
0
Wyoming
you will never get an allison to "free wheel" in the same way a 4L80/4L60 does. Its just the nature of a clutch-to-clutch transmission.
 
JoshH

JoshH

Daggum farm truck
Staff member
Vendor/Sponsor
Feb 14, 2007
13,712
773
113
Texas!!!
lotsofmiles said:
so, unlock the convertor, but its already unlocked. got it!:roflmao:
Click to expand...

No, the converter is not always unlocked. Your original post did not specify at what speeds you wanted it to coast. I stated two things you could do to lessen the engine braking affect. The first of which was making the converter unlock when you let off the accelerator pedal (which will help when you are going faster than ~45 mph). The second was to lower the speeds at which it downshifts when you are at 0% APP (which will help at all speeds).
 
adrenaholc1

adrenaholc1

New member
Apr 5, 2011
294
0
0
Butler Co. OHIO
Kind of on the same same subject as the OP. would it make sense to adjust tuning as to open the turbo vane more at fueling levels below 40 mm3 at any rpm? Just to reduce boost and back pressure at very light throttle like when cruising at 50-60mph on flat ground.
 
C

[email protected]

cmitchell17
Sep 8, 2008
251
0
0
I don't no of any table in the lly at least that you can directly control fueling while coasting. Tables like minimum injection quantity seem to not do anything just like a lot of lly tables seem to get ignored by the ecm.

It would be nice to be able to tune something to keep the drive line loaded up at all times to keep all the sloppyness and slack in the drive line from slamming back in forth when. You let of the gas and then press it.

When I let other people drive my truck they think the emergency brake is on, and they slam the drive line back in forth every time they let off the gas because they don't press the gas slow enough.

The Allison not having a sprat clutch in first gear combined with the braking effect makes for really bad driveability which most people probably don't care about.

I can't really tell from the logs, but is the truck coasting keeping the engine alive? Or is it fueling a small amount to keep the engine running when coasting with the tc unlocked? I would guess the tc would work in reverse to to keep the engine running?
 
adrenaholc1

adrenaholc1

New member
Apr 5, 2011
294
0
0
Butler Co. OHIO
adrenaholc1 said:
Kind of on the same same subject as the OP. would it make sense to adjust tuning as to open the turbo vane more at fueling levels below 40 mm3 at any rpm? Just to reduce boost and back pressure at very light throttle like when cruising at 50-60mph on flat ground.
Click to expand...

I only assume this would help mileage cause when I burnt the stock charger up and drove the truck for about a week it was like the charger was way to big and wouldn't build boost till higher rpms. However the mileage seemed to improve as long as I was light on the pedal. Then again I was going off the Avg on the dic display which is known to be inaccurate.
 
You must log in or register to reply here.
Top Bottom