Skip the auto shop - Our mechanics make house calls

Q: My car is accelerating on its own.

asked by on

Once I start my car it start to accelerate on its own , like if someone is pressing the gas , if I put it in drive the car starts picking up speed & its hard to brake . I feel like I'm steping on both at the same time .

My car has 140000 miles.
My car has an automatic transmission.

Inasmuch as you are writing in about uncommanded (aka, "unintended") acceleration, I can tell you the National Highway Traffic Safety Administration, one of the Federal agencies that tracks vehicle defects, would love to hear from you. You can file an on-line complaint at their website www.NHTSA.gov (go to https://www-odi.nhtsa.dot.gov/VehicleComplaint/ ) or call in the Complaint to the NHTSA Vehicle Safety Hotline (Toll-Free: 1-888-327-4236 / Hearing Impaired (TTY): 1-800-424-9153).

Engine speed is dependent on the amount and rate at which air and fuel are admitted by the engine control systems into the combustion chambers. Based on the NHTSA complaint database, and other sources, relative to your specific year, make and model, I would recommend testing your idle air control (IAC) valve as well as cruise control system. Both of these systems have been implicated in the type of symptom you are describing.

If the problem is not found in either system, since you are describing this as a non-intermittent problem, it should not be too hard to narrow it down just by looking sequentially at each and every other component that controls the "rate" at which air and fuel are admitted to the intake system. While this issue remains unresolved, obviously you have to exercise caution and just remember that, if faced with wildly uncontrolled acceleration, simply turn the ignition switch to the off (but NOT "locked") position and then place the car in neutral, while being mindful of your surroundings and adjacent traffic.

I recommend having a certified mechanic, such as one from YourMechanic, come to your location to determine why the car is accelerating without cause and replace the idle air control (IAC) valve or inspect the cruise control system.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. My car is accelerating on its own.

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: Hi. I o I've got various codes to do with air flow to the engine. I changed all spark plugs and the main air sensor with no result

Hello, and thank you for writing in. There are several air intake and exhaust sensors that your codes may be pertaining to. Without the actual codes to help diagnose the problem it is difficult to tell. There are air intake...

Q: I have a 2000 infinity I30 that is possibly leaking trans fluid. The dip stick is completely dry but I put fluids in it about 4 da

Hi there. Absolutely do NOT put a stop leak product like Blue Devil or anything else to fix your transmission leak. These products are designed to plug leaks in gaskets or seals. However, the transmission depends on smooth flow of...

Q: can a alternator belt make car not start because I was driving my car and I ran out of gas and i put a little gas in? belt broke

Hi there. It is very difficult to diagnose this type of hard to start issue remotely due to the fact that both issues; running the vehicle out of gas and the alternator belt being broken can cause the car to...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
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...