1991 PM7 ECU Technical Reference
Technical reference for the 1991 PM7 ECU, including idle target configuration and sensor management.
The PM7 ECU is a specific engine control unit variant utilized in the 1991 Honda Civic and CRX chassis. This document outlines the configuration parameters for idle control and general sensor management.
Idle Control Configuration
Setting the target idle on the PM7 ECU requires adjustment of the specific memory address responsible for the idle RPM lookup table.
Important
Ensure the engine is at full operating temperature before attempting to calibrate or verify idle settings.
Target Idle Parameters
The target idle speed is determined by the ECU based on coolant temperature and electrical load. To modify these values, update the lookup table within the ROM:
| Parameter | Description | Typical Value |
|---|---|---|
| Target Idle | Base idle RPM at operating temp | 750â800 RPM |
| Cold Idle | High idle during warm-up | 1200â1500 RPM |
Sensor Management
The PM7 utilizes standard OBD0 sensor inputs. Refer to the following table for critical signal paths:
EACV
- ECU to EACV Solenoid
TPS
- Sensor to ECU
No matching connections.
Tip
If the idle is erratic, verify the EACV duty cycle and check for vacuum leaks in the intake manifold before modifying ROM values.