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Q: My car is having starting issues - 2002 Hyundai Sonata

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Figured I would give this a shot. I drive my car a lot and it's not in all time best condition. But, since it has been getting colder out when I first start my car it starts but the rpms drop and it turns off. ill try to give it a little power but if I give too much I get a knocking sound from the engine. Eventually I'll get it I t up enough that it stays on but usually when I first go to drive I press a little harder because it doesn't want to go. Hoping somebody can give me an explanation on what to do before I put it back in the shop! Thank you in advance!

My car has 255460 miles.
My car has an automatic transmission.

A: Hi there. From the description you have pro...

Hi there. From the description you have provided, your vehicle's start and stall may be more serious due to the knock you hear. Assuming the engine does not have a mechanical problem (e.g., collapsed or worn piston skirt, connecting rod bearing failing, oil pressure loss), it could be the fuel pump failing to produce enough pressure when cold.

Low fuel pressure could produce a knock if detonation is occurring from a lean condition. A fuel pressure test when cold could prove the fault. A bad or dirty idle air control valve could cause the stall but not the knock. I recommend having your vehicle's [starting and turning off](https://www.yourmechanic.com/services/car-starts-and-then-dies-inspection diagnosed and repaired by a certified technician, such as one from YourMechanic.

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