Q: Cold idle start

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I have a cold idol start every morning in my garage for about 20 to 30 seconds. When my Eddie Bauer is left out in the cold below 30° the cold idol start last a few minutes . I have been told it's a vacuum leak but I have searched everywhere and cannot find nor hear a vacuum leak. I have cleaned the butterfly and inspected all of the breather hose connections and electrical connections. I have also taken apart the MAF sensor and cleaned it also . Thanks I hope you can help DJ
My car has an automatic transmission.

Hi There, If I am understanding your question correctly, your Explorer has a high engine idle when starting on exceptionally cold mornings. This is normal when starting an engine in very cold weather. 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 which causes the motor to require more fuel in order to properly maintain the correct air/fuel ratio due to the atomization process of fuel at colder temperatures. 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. This is done with what is called a cold start injector which injects more fuel into the motor until the engine reaches a specific operating temperature. The computer simply feeds a little extra gas through the fuel injectors to start the engine and then maintains a certain amount of fuel supply to the motor until it is warm. Normally, this should last a minute or two until the engine temperature gets closer to normal operating temperatures. This can also be impacted if the thermostat is not functioning properly and not opening and closing at the proper temperatures which can cause the motor not to reach the correct operating temperature. I would recommend having an expert from YourMechanic come to your location to take a look at your vehicle and diagnose your cold start issue.

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