Skip the auto shop - Our mechanics make house calls

Q: On a good day car starts very easily in the morning or if rested for about 30 mins. However, it does not start when warm

asked by on

i have changes MAF sensor and Coolant temperature sensor. car starts easy at mornings and once started can run all day without stalling and cutting out . if u cut the engine while warm and leave it for a few minotes it wont start.Leave it rested for 30 minutes then it will start
My car has an automatic transmission.

A: Hey there. This is a common sign of a fault...

Hey there. 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 as the copper beneath them expands and contracts faster than the insulation around them. The insulation develops small fractures that open when heated and close when cooled. When open, they allow shorting of coil windings decreasing 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 manifold, 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 truck to properly diagnose the hard start and proceed with the proper repairs.

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: How do I fix my cruise control brake switch. Brake light stays on

Hello. This is caused by a problem with the brake light switch. When the switch fails internally, it shorts and causes the lights to stay on. If the brake lights stay on, then the computer thinks that the brake pedal...

Q: What could it be when the transmission won't engage in either gear

Hello, thank you for writing in. When dealing with an unresponsive automatic transmission, always start with checking the fluid level. If the fluid is not full, then you need to inspect for a leak, and repair that damage first. There...

Q: Excessive oil consumption, oil in spark plug holes, normal compression

The oil getting into the spark plug holes is from the valve cover and spark plug tube seals. Replace both of these and clean out spark plug holes of oil. This will help with the misfires and coils shorting out....

Related articles

P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...