List of underhood sensors/parts/etc. functions and locations and spark plug info

[My5ABaby]

Initial Set Coupler
Jumper before adjusting idle speed and mixture
Location: by the coolant overflow bottle; 2 spade green connector

Fail-safe system
- This is the list of what various things do if they fail
Air flow meter: maintains the basic value at preset value
Water thermo sensor: maintains a constant 176 degree Fahrenheit command (non-Australia is 68 degrees)
Intake air temperature sensor (inside AFM): maintains a constant 68 degree Fahrenheit command
Intake air temperature sensor (dynamic chamber): maintains a constant 68 degree Fahrenheit command
O2 sensor: stops the feedback correction
Throttle sensor: maintains a constant 100% command
Boost sensor: maintains a constant -96 mmHg command
Atmospheric pressure sensor: mains a constant sea-level pressure command
Coil with igniter (trailing): stop operation of the ignition system on the trailing side only

Fuel Injection Amount Controls
Affecting systems: intake air temperature sensor (on AFM); atmospheric pressure sensor; water thermo sensor; throttle sensor (TPS); boost sensor; crank angle sensor; ignition coil; variable resistor; AFM

Sensor and Switch Functions
AFM: intake air amount
Water thermo sensor: engine coolant temperature
Intake air temperature sensor: intake air temperature
Atmospheric pressure sensor: atmospheric pressure
Boost sensor (Australia): intake manifold vacuum
Water temperature switch: radiator coolant temperature
Clutch switch: in-gear condition
Neutral switch: in-gear condition
Throttle sensor: throttle valve opening angle
O2 sensor: exhaust gas O2 concentration
Starter switch: engine start condition
A/C switch: A/C load condition (on when the A/C is in use)
Inhibitor switch: D range load condition (N or P range = on)

Fast Idle System
Controls the degree of opening, by thermo wax, of the throttle valve, and by the amount of fuel increase. Engine coolant is led into the water thermo wax, the wax rod extends as the coolant temperature increases, turning the fast-idle cam, and the throttle valve is gradually closed.
Used during warm-up.

Air Flow Meter (AFM)
Detects air quantity and converts the flow of air measured to a voltage reading by mean of the potentiometer. This information is used by the control unit to determine fundamental injection quantities.
Improves response during acceleration.
Location: passenger side near headlight; connected between the long intake tube leading to the throttle body and the stock air box

Crank Angle Sensor
Output signals from the sensor are sent to the control unit where they are used to determine eccentric shaft angle and engine speed.
Location: drivers side of the engine block

5th/6th Port System
Above 4,500 rpm, the actuators open the port and allow additional airflow into the engine.
Location: passenger side of engine block; actuators are on the LIM

O2 Sensor
Generates a small voltage according to the ratio of the O2 concentration in the exhaust gas. Running rich causes a higher voltage and the control unit uses that information to reduce the injection amount (opposite for running lean).
Used to cause the catalytic converters to operate at their highest efficiency levels.
Location: exhaust manifold

Intake Air Temperature Sensor (in the AFM)
Corrects variations of the A/F mixture caused by changes in air density. Lower temperatures cause increased A/F amounts.

Intake Air Temperature Sensor (on the Throttle Body)
Location: underneath the BAC

Atmospheric Pressure Sensor
Prevents over-rich A/F mixture at high altitudes. Increases A/F mixture at higher than 760 mmHg.
Location: passenger side

Water Thermo Sensor
Maintains driving stability during cold weather.
Prevent engine stall after starting (cold condition) and to maintain idling stability.
Location: coolant neck

VCV (Vacuum Control Valve) System
Controlling factors: Air flow meter; water thermo sensor; throttle sensor; water temperature switch; ignition coil -->
ECU --> VCV solenoid -->
Uses: prevent knocking (during .5 seconds from start of acceleration; prevent backing (deceleration); prevent surging (under 1,200 rpm); reduce CO and HC emissions by exhaust gas temperature increase (130 seconds after starting engine or during warm-up)

BAC (Bypass Air Control)
Controlling factors: ignition coil; crank angle sensor (Australia only); throttle sensor; water thermo sensor; water temperature switch; intake air temperature sensor; ignition switch (cranking)
Bypass air control valve: bypass air is controlled electrically by a single linear-type solenoid and the control unit
Air bypass solenoid valve: supplies additional bypass air during cold starting
Uses: maintains a constant idle speed and stabilizes the idle when loads are put on the system (air conditioning, power steering)
Location: drivers side of throttle body

Throttle Sensor (TPS)
Improves response during acceleration.
Prevent bucking during deceleration.
Maintain idling stability.
Location: front side of the throttle body

Variable Resistor
Maintains idling stability and combustion increase.

Boost Sensor
Prevent bucking during deceleration.
Maintain idling stability.
Location: passenger side near headlight

Inhibitor Switch
Prevent engine stall caused by D load (cold condition).

Dashpot
Deceleration control
Location: firewall side of throttle body

Metering Oil Pump/System
Injects small amounts of oil onto the rotors providing lubrication where the regular oil lubrication system doesn’t.
Location: rod is attached to the front of the throttle body; pump is located near the main pulley

Power Steering Switch
Informs the control unit when the P/S is being used
Location: towards the drivers side of the P/S oil pump

Spark Plug Info
Front coil (next to the battery) is the leading coil pack.

One wire to the leading (lower) plug on the front rotor, other wire to the rear rotor's leading (lower) spark plug.

Doesn't matter which, they both fire at the same time, so you can have the front leading and rear leading plugs reversed with each other and not have any problems.

The rear coils (next to the master cylinder) are the trailings.

The front of the two trailing coils, goes to the front trailing (top) spark plug). The rear coil of the two trailing coils, feeds (you guessed it) the rear rotor's trailing (top) spark plug.

[Willub and Company]

really good post, should be a sticky!