1. Verify the Problem:
* Multiple Cylinders? Is it *only* cylinder #1, or are other cylinders also not firing? If it's multiple cylinders, the problem is likely in a component shared by multiple cylinders (distributor, coil, ignition module). If it's just #1, the issue is likely more localized.
* Spark Tester: Use an inline spark tester (available at most auto parts stores) to definitively confirm the lack of spark at the #1 plug wire. Don't rely solely on visually checking the spark; the tester gives a more reliable indication.
2. Ignition System Components (in order of likelihood):
* Distributor: Even with a new cap and rotor, the problem might be within the distributor itself.
* Points (if equipped): Older systems might use points and a condenser. Inspect these for wear, pitting, or incorrect gap. If present, carefully check the gap and replace if necessary. A faulty condenser can cause weak or intermittent spark.
* Pick-up Coil (or Hall Effect Sensor): This is the component inside the distributor that senses the position of the rotor. A faulty pick-up coil won't generate the signal needed to trigger the ignition module (or coil in simpler systems). Testing this requires a multimeter and understanding the distributor's wiring. A shop manual will be helpful here.
* Rotor Button: Ensure the rotor button is securely attached and making good contact with the distributor cap. A loose or worn button can cause misfires.
* Distributor Shaft: Check for excessive play or wear in the distributor shaft.
* Ignition Coil: The coil is responsible for boosting the low voltage from the ignition system to the high voltage needed for the spark plugs.
* Primary Resistance Test: Use a multimeter to check the primary coil resistance (should be within the specifications in your shop manual). A faulty coil will often have resistance readings far outside of specifications or an open circuit.
* Secondary Resistance Test: Check the secondary coil resistance (also specified in your shop manual).
* Visual Inspection: Look for any cracks or burns on the coil casing.
* Ignition Module (if equipped): Many 1978 cars use an ignition control module (also called an electronic ignition module or ICM). This module controls the ignition timing and switching of the coil. A faulty module often leads to intermittent or no spark in one or more cylinders. Testing often requires a specialized tool or oscilloscope.
* Wires: Check all high-voltage wires (from the coil to the distributor cap, and from the distributor cap to the spark plugs) for cracks, fraying, or loose connections. A cracked wire can leak high voltage and cause a misfire. Sometimes just touching a wire is enough to cause a short.
* Ignition Switch: A faulty ignition switch might not be providing the power needed to the ignition system. Make sure you're getting 12V at the correct points in the ignition system.
3. Testing and Procedures:
* Wiring Diagrams: A shop manual for your specific year and model Olds Cutlass is invaluable. It will provide wiring diagrams and component specifications.
* Multimeter: You'll need a multimeter to test the resistance of the coil and other components.
* Test Light: A test light can help trace power through the system.
* Careful Inspection: Look for any obvious signs of damage, corrosion, or loose connections.
4. Troubleshooting Steps (Systematic):
1. Spark Tester on #1 Wire: Confirm NO spark at the #1 plug wire with a spark tester.
2. Check Coil Primary Resistance.
3. Check Coil Secondary Resistance.
4. Visual Inspection of all wires and connectors.
5. If points are used, check their condition and gap.
6. Check for continuity at the pickup coil (if applicable).
7. If all else fails, check the ignition control module (ICM) if it is present.
Important Considerations:
* Safety: High voltage can be dangerous. Be careful when working on the ignition system. Disconnect the negative battery cable before starting any work.
* Professional Help: If you're not comfortable working with automotive electrical systems, it's best to take your car to a qualified mechanic.
By following these steps systematically, you should be able to pinpoint the cause of the no-spark issue on your Oldsmobile Cutlass. Remember to refer to a shop manual for your specific vehicle for detailed wiring diagrams and component specifications.
