Diagnosing Automobile Ignition System Problems - dummies

Diagnosing Automobile Ignition System Problems

By Deanna Sclar

If your car is having problems, and you think that your engine is getting enough air and fuel, you’re probably having ignition system trouble. On traditional vehicles, the “fire” that lights the fuel/air mixture is really electric current that’s stored in the battery, replaced by the alternator, monitored by sensors, and directed by the ECU to the spark plugs in the cylinders at the proper time. If something along the way goes wrong and the spark fails to reach the plugs, all the air and fuel in the world won’t produce combustion in the cylinders, and the vehicle won’t go. If the engine was running before it died, it’s probably not the fault of the battery, solenoid, or starter.

If just one spark plug suddenly malfunctions, the engine will continue to run on the other cylinders. It won’t run smoothly, but it will get you off the road and into a repair shop.

If your car has an electronic ignition system, the ignition module may have gone bad. Because these vehicles have high-energy ignition systems that operate at 47,000 volts or higher, the old technique of pulling a distributor or spark plug cable to test for a spark is unsafe. Whether the vehicle has a distributorless ignition system or has an electronic ignition, you need to have a professional check it out. The good news is that these systems aren’t prone to breaking down, so they probably aren’t the problem.

If your vehicle is an older model with a non-electronic ignition system, you can check the distributor cap to see whether the spark is getting from there to the coil and on to the spark plugs.