[e9999]

Originally Posted by turbocruiser

Let's make sure that the basics are correct though:

There is no such thing as "reverse load" on the engine. Even when engine braking down super steep grades load is never less than about 6 to 8%. Also, the throttle is never totally closed, and RPM could be almost redlined while the throttle is almost closed (engine braking down super steep grades especially after downshifting) and the load would still be 6% or more. Believe it or not load at idle is typically 12% with some small jumps up and down. IOW, the engine "works" to stay on regardless of how easy you make it work.

??
I don't know what you mean by load I guess. I meant mechanical work in or out of the engine. if you are engine braking, how can the load not be reversed if the fuel is cut off and if the losses in the drivetrain are not enough to slow down the truck by themselves (unlikely since you can coast for a long time on flat ground in N)? The fact that the engine rpm increases does mean there is work applied *on* the engine, no?


Also, remember that the guy at SG said that in some systems at least, when cutting off fuel completely, the ECM still produces fake numbers on AFR, fuel injected etc. If true, one would want to be careful about "data" shown on some of these systems.