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Q: Transmission is not shifting

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Car will not shift it gets to about 25 mph and won't shift I floor it and get it up to 4000 rpm and it makes a backfire noise after I do this a few times it start to run better I checked the fluid and it's ok

My car has 98000 miles.
My car has an automatic transmission.

This may be a sign of low transmission fluid or a faulty transmission control solenoid. As you know, automatic transmissions use pressurized hydraulic fluid to change gears. Every time a gear change is required, the car’s computer activates a transmission solenoid, which directs transmission fluid into the valve body to engage the correct gear. When this is faulty or not working properly, this can cause a delay in gear shifting or in some cases cause the car to not shift at all. This type of problem is amplified any time the transmission is low on fluid creating a drop in hydraulic pressure.

This may also suggest a failing speed sensor. The transmission speed sensor is a magnetic sensor that provides this information, allowing the transmission to shift smoothly. The sensor counts the internal number of revolutions of the transmission and transmits that information to the transmission control unit, where the data is used to determine the rotational speed. As the rotation increases, the control unit directs the changing of gears. When this is not working properly, this may cause the transmission to shift erratically or in some cases not at all. I would recommend having an expert from YourMechanic come to your location to take the car for a test drive to more specifically determine the cause for this.

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