Automatic trasmission gear lock when accelerating

Question

For awhile now since getting my first car (and only driving Automatic transmissions) I've had plenty of experiences where when making a turn out of a parking lot with my wheels turned a bit too much, or even when I'm switching lanes on the highway (jumping 55 to 65 due to trucks ahead) it seems that if I floor my car or push the gas too much, I end up with a dangerous acceleration block where my engine revs and stays around 4k RPM, and the only way out has been to release the gas and floor again.

On the second round it usually accelerates normally, and typically this issue never comes up when I'm not immediately doing a full floor.

Anyway, I wanted to know what causes this issue and if it's specific to automatic transmissions or any car type, or if this is an issue across the board. In addition, any tips on prevention and getting out of the gear lock are greatly appreciated.

I know that misfiring can cause stalled acceleration, however every time my engine has misfired I promptly replaced the spark plugs and the check engine light always came on, and I have a code reader so I occasionally check even if the light isn't on.

Also I know that turning the wheels a bit too much might cause a bit more tension on acceleration, but shouldn't cars be able to make tight turns (such as when on a blind curve) rapidly?

Answer 1

What you are describing sounds like activation of the automatic's kickdown switch. Which is just that, a switch that forces the engine to downshift to provide more immediate acceleration. This is normal, and is usually a physical switch attached to the end of the gas pedal's travel path. It is activated when, say, 90% or more throttle depressed. Newer cars activate this just using the Throttle Position Sensor data.

Either way, this is designed in on automatic vehicles. Otherwise, if your car had just shifted into overdrive and you really need to accelerate, you'd have no way to force it to downshift (although some cars have a separate overdrive lockout switch). It is so your car can provide more immediate feedback. Think emergency situations, drag racing, late for work, etc.

When the kickdown switch is activated, the car will only downshift if possible. If you are already at 5000 RPM it will not downshift again and force the engine past its redline.

Usually upon letting off the pedal (not necessarily all the way) the car will shortly return to normal.

This is in addition to any programmed downshifting due to engine load. Which may be what you are encountering. A car is much harder to move with the wheels turned all the way, and depending on other factors, the car's computer may detect a large amount of engine load and downshift. Some cars handle this more gracefully than others.