Q: My car is juddering between 20 and 30 miles per hour And high revving after 40. Your issue or question fully describe your

asked by on

My car is starting a little slowly. When you drive it between 20 and 30 miles per hour it starts juddering. It drives slowly and if I push down on the the gas at 40 miles per hour to get on the highway it revs really high and then when I let off it's stops for a little bit and may judder more. What is it?

My car has 175000 miles.
My car has an automatic transmission.

What you are describing may be a result of a faulty speed sensor, potentially low transmission fluid or a even a faulty transmission control solenoid. As your vehicle travels down the road, the computer analyzes data being sent by vehicle speed sensors and engine speed sensors. Based on this information, the Engine Control Unit (ECU), or the Transmission Control Unit (TCM), executes the appropriate upshifts and downshifts by sending a signal to one of several shift solenoids. These transmission solenoids have spring-loaded plungers inside them, which are wrapped with wire. When this coil of wire receives an electrical charge from the TCM / ECU, it causes these plungers to open, allowing transmission fluid to flow into the valve body and pressurize the desired clutches and bands. When this happens, the transmission changes gears and you continue down the road. The computer controls the transmission solenoid in several ways. If the vehicle is equipped with a dedicated Transmission Control Unit, it can open or close the hydraulic circuit using a direct 12v signal. In some cases, the Engine Control Unit (ECU) can control the solenoid’s plunger by turning the ground circuit on and off. When this is not working properly, this can cause a jerking reaction, a delay in shifting or in some cases may cause the transmission to hesitate in shifting gears. I would recommend having a professional from YourMechanic come to your location to diagnose and inspect your transmission.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. My car is juddering between 20 and 30 miles per hour And high revving after 40. Your issue or question fully describe your

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Experiencing a "rough shift" from 2nd to 3rd gear

This kind of reaction is often 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...

Q: How do I program the HomeLink?

You can use the universal garage door opener to open your own garage door or another garage door of a friend or family member. Hold the remote control transmitter between one and three inches from the control buttons for...

Q: I just changed the transmission with a rebuild from the transmission shop and I followed all the directions an it still doesn't work

Hello. Yes, problems with the transmission controller can prevent the transmission from going into gear. Double-check the fluid level to be sure it is at the proper level. Also, double-check the hydraulic pressure from the transmissions input pump to be...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.