What Are the Reasons for Difficult Cold Starts in Cars?
2 Answers
One of the most common reasons for difficult car starts is a faulty fuel injector. There may also be the following three situations: 1. Faulty fuel pressure regulator: The fuel pressure in the fuel system directly affects the mixture concentration. If the vehicle has difficulty starting, the fuel pressure should be checked first, and the fault location should be determined by inspecting the fuel pressure regulator. 2. Coolant temperature too low: If the temperature inside the engine is insufficient, both the fuel and lubricating oil temperatures will be inadequate. Therefore, during a cold start, more fuel should be injected to meet the power requirements. Poor fuel atomization at low temperatures leads to reduced ignition energy, affecting performance and causing the car to shake. 3. Excessive carbon deposits leading to frequent faults: Gasoline sprayed by the cold start injector can be largely absorbed by carbon deposits, resulting in an overly lean mixture during cold starts and making it difficult to start.
I've been driving a taxi for nearly twenty years, and cold start difficulties are all too common, especially in winter. The most frequent issue is an aging battery that can't hold a charge in cold weather, resulting in clicking sounds or weak cranking when turning the key. For older vehicles, it's also essential to check the spark plug gap—excessive erosion can prevent ignition, and you might even smell gasoline from the exhaust. Engine oil is another critical factor; if it's too thick, it turns into sludge in the cold. Last time my car wouldn't start, it was due to using the wrong oil viscosity. Clogged fuel injectors are even more troublesome—poor atomization makes the fuel spray like a water gun, leaving the cylinders drenched. The worst culprit is carbon buildup on the intake valves; thick carbon deposits can steal fuel, causing an overly lean air-fuel mixture. If the RPM fluctuates wildly during a cold start, it's likely due to a faulty coolant temperature sensor sending incorrect data to the ECU. And if pumping the throttle a few times actually helps the engine start, the problem probably lies with the intake pressure sensor.
