I am running a SBC 305 with a 4l60 which is manually controlled for now because the wiring was converted for carb use. I am in the process of getting the 7747 programmed with the help of Dave W (bin is set as manual trans). The engine/trans are in a Toyota FJ40 which is mainly used as a wheeler. I only drive on the street to get to and from off-road parks.

One of the things that many auto's lack is decent engine braking. With my previous Q-jet and the low first gear in the 4l60 I actually had decent engine braking. Not great, but not terrible. At least until I moved up to 36" tires. Not so good now. My axle gears are kind of tall (4.10's running 36" tires) which hurts in this department. I will be performing a gear swap (4.88's) in a couple years when I can afford it and that will help a bit.

Anyway, the purpose of this post is to learn more about getting better engine braking in first and second gear for those long downhill trails. I want to get my head around the needed changes to improve this when the time comes to mod the bin for it and not to make the vehicle undriveable on the street.

I am thinking that I need to change the following 3 tables.
DFCO - Enter ~ Exit RPM
DFCO - Enter ~ Exit MPH
DFCO - Enter ~ Exit MAP

I run about 45 KPa at idle in gear not moving. In 4-low and second gear I think 3,000 RPM might get me to 20MPH if that, but i haven't driven off-road in months so I don't recall exactly. When I enter a steep decline I am usually moving at a crawl with no throttle rather than slowing down from high speed.

What might be good settings for DFCO using the above info?

DFCO - Enter ~ Exit RPM
current enter: 1450, exit: 1200
proposed enter: 2000, exit: 950 (I'm not so sure of these values. I don't want to drop out if the RPM climbs over 2k on a steep hill)

DFCO - Enter ~ Exit MPH
current enter: 25, exit: 20
proposed enter: 20, exit: 1

DFCO - Enter ~ Exit MAP
current enter: 20.63, exit: 31.88
proposed enter: 30, exit: 40

I don't know if the above values make sense for DFCO or not so please post away :)


Thanks,

Steve