If your vehicle is newer than the mid 2000s, it likely doesn’t have a once-popular ignition system which uses a distributor cap and rotor.  But if your vehicle is old enough to have them, it’s important to make sure they receive regular attention since they’re instrumental to your engine running smoothly.

Here’s now a distributor cap and rotor system works.  The distributor cap sits on top of the distributor, while the rotor goes around underneath it. They take high-voltage electricity from the ignition coil and send it to each spark plug in the correct firing order. That is what enables your engine to run smoothly and efficiently.

Because they’re mechanical, eventually the distributor cap and rotor will wear out. Think how much heat, vibration and electrical stress the distributor cap is endures. That can result in it cracking and the terminals corroding.  Another problem may develop called is called carbon tracking where a line of carbon acts as a conductor to bypass the usual route the electricity takes. Plus, the rotor can wear down and the spark may wind up going to the wrong cylinder.

You’ll notice signs like the engine is hard to start (if it starts at all), it misfires, your fuel economy deteriorates, your power decreases or idling is rough. If you drive in a damp or humid climate, moisture can also interfere with the electrical path.

It’s important to have a technician regularly replace the distributor cap and rotor, typically anywhere from 30,000-50,000 miles/50,000-80,000 km.  Each manufacturer has its own interval, so it’s best to follow their recommendation.  After the distributor cap and rotor are changed out, you should notice much better performance. And your vehicle will be more likely deliver the reliability you’re expecting.

Commerce Auto Repair
9575 Commerce Rd.
Commerce, Michigan 48382
248.363.3749

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