How to improve this auto. trans. acceleration test
Today I tried running an acceleration test in the minivan with automatic transmission.
Engine is warmed up from previous driving.
Reset manufacturer's avg economy display and punch in a throttle setting from a dead stop at a stop sign turning right and holding constant throttle to 40mph noting TPS setting from scanguage --
Then coast engine on to the same landmark each time.
Note mpg from manufacturer's display while rolling past landmark.
Easy to feel different levels of acceleration by butt gauge. Unfortunately I decided that since trying to maintain a constant 40mph on a constant slope and coasting should BOTH use constant GPH I would just coast because it's easier. But I after running it realized the results would be skewed by the different times coasting at at different average speeds.
Other sources of error:
1) The manufacturer's display updates every 2 seconds (same as Scanguage on "normal" setting, right?) and each run is fairly short.
2) I didn't record coasting time or final coasting speed so I can't mathematically correct this part.
3) I started with engine hot so I could do all the runs in a row without this variable. BUT I'd really like to know if it makes a difference starting cold, especially from this particular stop.
I didn't worry about rpms etc. since it isn't a stick. I just want to get a good idea of how the acceleration should feel while keeping my eyes on the road.
Anyway here's the results such as they are:
24 17.9 this feels pokey
28 18.4 this feels about normal "moderate"
32 20.0 \__ these feel like accel. "smartly" but not peeling out
33 20.0 /
39 19.2 FAST, just under spinning at the stop, but not
continuing to push the pedal down to WOT
after pulling away.
I'm going to try keeping a log of individual cold starts to 40mph and then maintaining 40mph to my landmark over the next several days on normal trips. I'll note temperature as well.