I have a misfire on the #1 plug. I changed the plug and the misfire went away for about 15 minutes, then it started again. So, I changed the sparkplug wires. No change. So, I changed the coil pack......no change, still misses. I changed the plug again and the miss went away again......... for about 20 minutes.

HELP


ash

 

Try this.

Specifications
General
Coil resistance 0.2 to 1 ohm
Crank angle sensor resistance
Between terminals G1 and G2 110 to 210ohms
Between terminals Ne1 and Ne2 110 to 210 ohms

Torque specifications
Crank angle sensor locknuts 69.6 to 96 in-lbs

Ignition system
The ignition system includes the ignitions switch, the battery, the crank angle sensor, the leading and trailing side coil/igniters, the primary (low voltage) and secondary (high voltage) wiring circuits, the spark plugs and the spark plug wires.
When working on the ignition system, take the following precautions:
a) If the engine wont start, don’t keep the ignition switch on for more than 10 seconds.
b) Never allow an ignition coil terminal to contact ground. Grounding the ignition coil can damage the igniter and/or the coil itself.
c) Don’t disconnect the battery when the engine is running.
d) Make sure the igniter is properly grounded.

Ignition Check
1 Attach an inductive timing light to each plug wire, one at a time and crank the engine.
A) If the light flashes, voltage is reaching the plugs.
B) If the light does not flash, proceed to the next step.
2 Inspect the spark plug wire(s), and spark plug(s).
3 If the engine still wont start, check the coil/igniter assemblies.

Leading Coil Check
1 Detach the cable from the negative battery terminal.
2 Detach the high tension leads from the coil Note that the leads are marked (white dot on high tension terminal No. 1 and white band on leading high tension lead No. 1) If the leads on your vehicle are not marked, be sure that you mark them to prevent incorrect reassembly.
3 Remove the plastic cover from the primary terminals of the coil.
4 Using an ohmmeter, measure the resistance between the primary terminals of the coil and compare you measurement to the value (specifications listed).
5 If the indicated resistance is not as specified, replace the leading coil.

Trailing Coil Check
1 Detach the cable from the negative battery terminal.
2 Remove the plastic cover from the primary terminal.
3 Detach the high-tension leads; the leads should be marked (a white dot on the N0 .1 high tension lead). If they’re not marked on your vehicle, be sure that you mark hem to insure proper reassembly.
4 Using and ohmmeter, measure the resistance between the primary terminals and compare your measurements with the value listed in specifications.
5 Repeat this procedure for the other trailing coil.
6 If the indicated resistance of either unit is not within specifications, replace it.

Igniter
1 Testing the igniter assemblies requires special equipment and is therefore beyond the scope of the home mechanic. Take the vehicle to a dealer service department or other qualified repair shop to have the igniters checked.

 

Why does it not miss for a short time after changing the plug? Really weird!

 

NO. Try this. Next time if the flashing is irregular on one of the two LEAD plug wires, REVERSE the inductor that you have clamped on that wire. Usually it will have an arrow on it pointing the direction of the sparkplug. So the next time have the arrow on the inductor pointing in the direction of the coil instead.

The light should flash steady now. It's in the fsm.

 

How did you find out the "#1 plug" (L1?) is misfiring?
Are you using an inductive timing gun?
If so, those things are notoriously inconsistent on the RX-7 ignition system.


-Ted