1991 ACURA NSX fuel

key fob battery keyless sport mode maintenance adblue reset compression ratio

Page 1085 of 1640

ACURA NSX 1991 Service Repair Manual
3. Fuel Cut-off Control

During deceleration with the throttle valve closed, current to the fuel injectors is cut off to improve fuel economy

at speeds over 1,500 rpm.

Fuel cut-off action also take

3. Fuel Cut-off Control

During deceleration with the throttle valve closed, current to the fuel injectors is cut off to improve fuel economy

at speeds over 1,500 rpm.

Fuel cut-off action also takes place when engine speed exceeds, 8,300 rpm, regardless of the position of the

throttle valve, to protect the engine from over-revving.

4. A/C Compressor Clutch Relay

When the ECM receives a demand for cooling from the air conditioning system, it delays the compressor from being

energized, and enriches the mixture to assure smooth translation to the A/C mode.

5. Evaporative Emission (EVAP) Purge Control Solenoid Valve

When the engine coolant temperature is below 1 58 °F (70°C) the ECM supplies a ground to the EVAP purge control

solenoid valve which cuts vacuum to the EVAP purge control diaphragm valve.

6. Intake Air Bypass (IAB) Control Solenoid Valve

When the engine speed is below 4,800 rpm, the IAB control solenoid valve is activated by a signal from the ECM.

Intake air then flows through the smaller chamber, and hight torque is delivered. To increase air flow at engine speeds

higher than 4,800 rpm, the solenoid valve is deactivated by the ECM, and the intake air flows through the larger

chamber.

7. Exhaust Gas Recirculation (EGR) Control Solenoid Valve

When the EGR is required for control of oxides of nitrogen (NOx) emissions, the ECM supplies ground to the EGR

control solenoid valve which supplies regulated vacuum to the EGR valve.

ECM fail-safe/back-up Functions

1. Fail-Safe Function

When an abnormality occurs in a signal from a sensor, the ECM ignores that signal and assumes a pre-programmed

valve for that sensor that allows the engine to continue to run.

2. Back-up Function

When an abnormality occurs in the ECM itself, the fuel injectors are controlled by a back-up circuit independent of

the system in order to permit minimal driving.

3. Self-diagnosis Function [Malfunction Indicator Lamp (MIL)]

When an abnormality occurs in a signal from a sensor, the ECM lights the MIL and stores the diagnostic trouble code

in erasable memory. When the ignition is initially turned in, the ECM supplies ground for the MIL for two seconds

to check the MIL bulb condition.ProCarManuals.com