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Q: Difficult startup, chugging and rough revving

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My car has difficulty starting. The first time I try to turn it up, it starts pretty quickly. But, during the day, the startup becomes difficult. If I go somewhere for a while and go back to my car and try to turn it on, it has troubles starting. At very low RPMs, it can start with a lot of chugging. Occasionally, when it wouldn't turn on at all, I would give it gas and it would start revving up roughly as I turn the key, keeping my foot on the gas pedal. At that point, I cannot let go off the gas so as not to let it turn off completely. I go to RPMs as high as 2500 for a few minutes. Then, the car would idle and can run normally. While this is happening, the gasoline can be smelt. Also, there is white residue from the exhaust. What do you think could be the problem? Is this serious? Thank you.

A: Hello. If the engine is having trouble star...

Hello. If the engine is having trouble starting after it has ran for a while and you are getting the smell of fuel, then it may be a failing fuel injector or an issue with a bad sensor. Most of the time this is caused by a bad crank position sensor.

When this sensor stops reading, the engine will not start because the computer cannot see an engine RPM reading. I would start installing a scan tool to see if the crank sensor is reading and to see if the coolant temperature sensor is reading correctly. If not, then it needs to be replaced. If it is fine then the fuel system needs to be checked for leakage. If you are going to have this repaired, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose car's rough starting issue.

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