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Q: Car not starting sometimes

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My van starts right up in the morning but after being driven for a while it sometimes won't start again and I have to wait about an hour until it will start again. Unless the car is failing, no one can diagnose it and it only fails at the most inopportune times. I've had some ignition thingy (technical term) replaced. I have a new fuel pump and spark sensor. It's baffled a few mechanics. It turns over just fine so it's not a starter issue. It just keeps turning over, and over, and over... Any thoughts?

My car has 147000 miles.
My car has an automatic transmission.

This is a common sign of a faulty ignition coil. Ignition coils are coated with a varnish-like insulation that becomes brittle over time after being stretched then contracted repeatedly The insulation develops small fractures that open when heated and close when cooled. When open, they allow shorting of coil windings and decrease or eliminate the coil’s ability to function. This type of temperature cycling happens because every time you shut the engine off, the fan stops running, the coolant stops flowing and the temperature under the hood rises. Every time you start the engine again the coolant flows, the fans turn on, and the temperature drops. When this heat dissipates and is absorbed under the hood, it is trapped causing this cycling effect. Components that contain heat sensitive materials include parts like coils, injectors, igniters, and some sensors. Any of these may be potentially subject to this same kind of heat problem which can be very difficult to trace. I would recommend having an expert from YourMechanic come to your location to take a look at your vehicle to properly diagnose your ignition system.

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