RPM goes up but the car does not accelerate
The buyer question: "RPM goes up but car doesn't accelerate"
Arrange an inspection before driving in traffic or on a long trip. Stop if the car cannot maintain speed, smells strongly of hot friction material, or shifts violently.
What could cause it
More than one problem can cause the same symptom. These are places to inspect, not a diagnosis.
- Clutch slip in a manual transmission
- Automatic or CVT transmission slip
- Low, degraded, or leaking transmission fluid where the vehicle uses it
- A control, axle, or drivetrain problem
Safe things to check
Keep clear of moving parts, hot components, and traffic. Use the owner's manual for vehicle-specific instructions.
- Note the gear, temperature, road grade, and whether RPM rises during a shift or under steady throttle
- Look for transmission warning lights or fluid spots from outside the car
- Do not repeatedly force acceleration to reproduce the slip
Stop driving if the car cannot accelerate with traffic, the transmission engages harshly, a burning smell appears, or the symptom worsens quickly. Arrange professional help.
What a mechanic may check
A technician may inspect for leaks, check fluid according to the vehicle procedure, scan the transmission, test clutch or converter behavior, and inspect axles and mounts.
If you are considering this car
This symptom can change the risk and cost of a used car. Ask for a transmission diagnosis, fluid-service history, and an independent inspection before you consider it.
Questions for the seller
- Is the transmission manual, automatic, or CVT, and when does the slip occur?
- Has the transmission, clutch, converter, or axle been repaired?
- Will the seller provide service invoices and permit an independent road test?