1987 Nissan Sentra After it warms up

Hi Norm,

Thank you for the donation.

Is your vehicle carburetted or fuel injected?

This should be the ECCS system as shown in the diagram.

Here are procedures for retrieving trouble codes. Let me know if any found.

STARTING & CHANGING MODES OF SELF-DIAGNOSIS

Turn ignition switch to "ON" position. Turn diagnostic
mode selector of ECU fully clockwise and wait for inspection lights to begin flashing. See Fig. 11.

Count the number of flashes. Right after the number of flashes which correspond to the diagnosis mode you wish to enter appears, immediately turn the mode selector fully counterclockwise.

MODE 3: SELF-DIAGNOSIS

1. The ECU constantly monitors the operation of sensors and actuators, regardless of ignition key position. When a malfunction is suspected, the information can be retrieved from system memory by turning the diagnostic mode selector (or on/off on Van models to "ON" position) on the side of ECU. See Fig. 11.

2. When properly activated, the Red and Green LED lights will flash appropriately to signal the number of the malfunctioning part(s). First the Red light will flash and then the Green light will follow. Red light flashes refer to number of tens in the code number. Green light flashes refer to number of ones in the code number.

3. All codes are classified in 2 digit code numbers. For example, if Red light flashes once and Green light flashes twice, code 12 is detected. If diagnostic code(s) have been obtained, refer to the SYSTEM INSPECTION TABLE that applies to the model vehicle your working on and perform the test that it refers you to.

4. If no diagnostic codes are obtained, define the driveability symptom and refer to the DRIVEABILITY INSPECTION TABLE that applies to that vehicle (perform Mode 4 first). There you will find a list of common driveability symptoms, find the symptom that your vehicle is exhibiting and check all the components in that column as well as any tests listed.

5. If engine cranks, but fails to start, crank engine more than 2 seconds prior to starting self-diagnosis. Do not erase stored memory codes prior to self-diagnosis or intermittent malfunctions will be lost. Stored memory is lost if battery is disconnected or if Mode 4 is selected after Mode 3.