Q: When I start my car on a cold morning I have to pump the accelerator to get it to start.

asked by on November 16, 2016

When I start my car in the morning and cold temperature I have to pump accelerator so it can start.

My car has 116000 miles.
My car has a manual transmission.

As a general rule, car engines do not like cold weather and do not do operate as well in cold weather. When you start your car in the morning and turn the key to on, the coolant temperature sensor immediately reads the temperature of the coolant and relays this to the computer indicating that the coolant is cold. The computer then knows at this point that it needs to enrich (add more fuel) the air/fuel mixture at startup due to the change in air density. When you start the car, you will notice that it idles high for a period of time until the engine warms up. This is the enrichment cold start process.

On the old carburetor engines, you pressed the gas pedal before starting to set the choke position and give a squirt of fuel into the engine via the accelerator pump. This was necessary because the carburetor does not feed fuel as efficiently as a fuel injection system does at low (starting) RPM. A cold engine also needs a little extra fuel to compensate for questionable vaporization at low temperatures.

The fuel injection system does nothing until the engine is turning (starting or running), so pressing the pedal before you start will make no difference. The fuel injectors work at any RPM, so a choke is not necessary. The computer simply feeds a little extra gas through the fuel injectors to start the engine. Cold temperature fuel delivery is also managed by the computer which checks the mixture with oxygen sensors.

With that said, it is likely that you may have an issue with a faulty oxygen sensor which is what provides feedback to the engine after it starts as exhaust gases flow through the catalytic converter and past the oxygen sensors.

I would recommend having an expert from YourMechanic come to your location to diagnose your starting issue and service your oxygen sensors if necessary.

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