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Misfire Problem

Good day good people. Hoping someone can assist with a weird problem.

Driving a 1984 Opel Rekord 2.0 (4 Cyl)

The car is currently running on only 3 Cyl. Replaced the plugs, and replaced the plug leads. Problem persists. Through some troubleshooting, I have determined that number 4 Cyl is the offending one.

Funny thing is, when I pull the number 4 plug lead half way off the plug, it starts running right. Tested this with different plugs, and different leads.

Any ideas on what the cause may be?

Greetings

Try finishing the tune up by replacing cap and rotor.

3 Likes

& compare the resistance (ohms) from the distributor cap to each of the plugs. It sounds like you have a high resistance connection at some point in the 4th cylinder high voltage path. Check the resistance to chassis ground too. (Good idea to remove the battery negative connection before checking ignition system resistance.) Weak coil can cause this symptom, but since it only occurs on cylinder 4, the coil is probably ok. No harm done to measure the resistance of the coil’s primary and secondary turns though. Might provide a clue. A corroded ignition system ground connection is another possibility.