Accidental Transmission discovery (bump started my automatic)

[RH77]

This is the best I can come up with from the shop manual...

This is on the '98 Honda/Acura 1.8L base Integra engine (B18b1)

The PGM-FI system regulates idle based on:
Overview

1. Sensor Inputs
2. Control Module Program (the brains)
3. Result/Output (sensor or device)

Process
Sensor Inputs Relevant:

• Vehicle Speed Sensor
• Alternator Charge Signal
• Primary Heated O2 Sensor
• Transmission Gear Position Sensor
• Batt Voltage
• Fuel Tank Pressure Sensor

These and others are fed into the ECM. The "Electronic Idle Control" program is part of the computer, and likely outputs to:

• Alternator Output Control
• Idle Air Control Valve
• Ignition Control Module
• Fuel Pump

Hope this helps.

RH77

What it doesn't really get into is the following observation:

Lots of cars I drive will increase engine speed based on brake vacuum at idle. With the vehicle stopped and in P or N, pump the brakes quickly and note if idle increases.

[Chris D.]

On your newer vehicles, doesnt turning the ignition off turn off the SG as well?
Some vehicles have electronic speedometers vs cable and you mite not see any #'s for mileage by doing the engine off trick..

keep in mind, cars weren't designed to drive in motion with the engine off..
The transmissions weren't designed to do this and the results could be good or bad..
The manufacturer wouldnt know what to say if you asked if it was ok, they'd just take the easy way out and say it's bad insted of hard facts..

Talk to some transmission shops and ask people that work on these if there would be any harsh effects..
thats my mindset.

or get a manual transmission

[diesel_john]

during coast down, engine on, neutral, the engine maintains high idle to either to burn hydrocarbons(keep O2 sensors hot)(or cats) or keep the speeds in transmission matched, should i pull it back into gear. if i unplug the VSS for a test, i wonder if it will shift at all.

[s2man]

My transmission is dumb; no connection to the ECU. So my high NC engine rpm's can only be coming from input from the trans. I hadn't considered computer controlled trannies, so we may have been apples vs. oranges. But I think that even if you can fool the ECU into thinking the engine should be idling, you'll still get increased rpm induced by the transmission. As I said, my ECU is feeding idle quantities of gasoline, but my engine is turning 2X idle rpm on the highway. Engine rpm reduces as the vehicle speed reduces.

[apgrok1]

Ok, I'm back from the weekend and I have to eat a little crow. On my Cirrus, I have come to the conclusion that the injectors do not shut off on deceleration, but my wife's Kia Minivan does shut down as the deceleration is much more than in my Chrysler (the Cirrus coasts farther). In my car, there is more deceleration by turning off the key compared to coasting with my foot off the pedal. Also, I lost FE by shuting the engine down and bump-starting.

[elhigh]

Originally Posted by apgrok1

A quick calculation shows that stator rpm in top gear at 30 mph is 1090rpm. If the stator is running faster that the engine by 25%, then engine rpm is 812, which is probably lower than idle. Also, the slower the TC speed, the less efficient it will be. There is probably an exponential drop off in which the TC housing would finally quit turning.

My engine idles around 700rpm. Smaller engines idle faster, YMMV