Stalling in Automatic Transmission Vehicles
Automatics
Automatic vehicles use what’s called a torque converter to manage transmission fluid and keep your engine running while at a stop. If your torque converter fails, the engine can stall out. Torque converters can fail for many reasons, including dirty fluid, overheating and problems with stall speed, which is the RPM at which your torque converter shifts power from the engine to the automatic transmission. In order to check your torque converter, you might have to perform a stall-speed test. Here’s how:
1. First, find out what your car’s RPM should be in the car's manual, then locate your tachometer (a tool that measures RPM).
2. Place immobilizers behind your wheels to prevent your car from moving. Crank that parking brake. (Then crank that Soulja Boy.)
3. Press the foot brake all the way to the floor and start your engine. Vroom, vroom. Change gears from park to drive, but instead of hitting the gas pedal, do not take your foot off the brake. We repeat: do not take your foot off the brake!
4. Keep pressing the brake pedal, but use your other foot to engage the accelerator pedal for a maximum of five seconds. Check your tachometer for the stall speed and see if it reads lower than it should be. When you're done, be sure to remove your foot from the accelerator pedal first, then the brake pedal. Then you're safe to crank the parking brake back down.
5. If you need to get a new torque converter, visit an auto shop. Or, if this whole process sounds like something you totally want to avoid, just head to a mechanic and ask them about performing a stall-speed test for you. They can make a recommendation on whether or now you need a new torque converter.
