Skip the auto shop - Our mechanics make house calls

Q: Starts and idles fine but then stalls. What causes this?

asked by on

Truck starts and idles just fine but after 15-30 minutes it warms up and dies. But if you give it 30 minutes or so, it will crank but up and i can't get it to stall again.

My car has 150000 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 repeated as the copper beneath them expands and contracts at a higher coefficient than the insulation. 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. The areas in and around the tops of the combustion chambers, the exhaust manifolds, and the exhaust components are hundreds of degrees hotter than the outside temperature under the hood. 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.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: My car is rattling am I still able to drive it

Rattling noises have many varied causes, some more serious than others. Rattling can be caused by a loose or worn sway bar, strut, body panel, or other suspension component or even the exhaust system. As you are describing it, the...

Q: ignition coil has a melted connector.

It sounds like the coil primary side circuit has excessive low resistance, and is like a short. This could have overheated the wiring. I would recommend replacing the coil and also replacing or repairing connector. If you would like to...

Q: I need to buy an alternator today. Mine had to much wattage due to my new sub and amp. How do I know what alternator to buy? 2003 Chevrolet Suburban 1500

Hello - the real question here, and this is for your sound system person, is "How many watts does all this new gear pull?". Then you calculate how many amps that translates to what capacity alternator you need. (Amps =...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.