Honda Prelude 1993 Service Manual page 1170

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Table of Contents

lgnllion Timing Control:

The programmed ignition (PGM-|G) used in this engine provides optimum control oJ ignition timing. A microcomputer

determines the timing in response to engine speed and manifold vacuum. The input signals are transmitted by the

TDC/CKP/CYP sensor, throttle position (TPl sensor, engine coolant temperature (ECT) sensor, and MAP sensor. This system,

which is not dependent on a governor or vacuum diaphragm, is capable of sefting lead angles with complicated charac-

teristics which cannot be provided by conventional governors or diaphragms.

Basic Control:

The control unit has stored within it the optimum basic ignition timing for ope.ating conditions based upon engine speed

and intake maniJold pressure, With compenssting signals from sensors, the system determines optimum ignition timing

and duration for ambient conditions and sends vottage pulses to the lCM.

Compensation of ignition timing:

Control at Start:

lgnition timing is fixed at 7o BTDC Jor cranking. The cranking is detected by the TDC sensor (cranking rpm) and slarter signal.

Engine coolant temperature (ECT) com-

Compensation ltem

Related Sensor and Information

TDC/CKP/CYP sensor

lgnition timing is controlled to the ta.get speed

with compensation according to the idling speed.

Comoensation at warm-up

Lag angle is adjusted according to warm-up con-

ditions to bring about a good balance between

operating performance and exhaust gas level.

ECT compensation

Compensation for lead angle at low engine

coolant temperature and lag angle at high engine

coolant temDerature.

Troubleshooting