Q: When you slow down then re-accelerate..sounds like severe downshift.

asked by on

When I slow down then re=accelerate, very easily, it's like the car downshifts from 6th to 1st gear. This is a 300hp engine. I accelerate as though I am in a 1985 Chevette automatic, yet it slams down as though I went to WOT, in a Corvette?

I am a 52 year old male, and I normally drive this car like an old lady. I rarely push this car, though it is very powerful. I bought Jan. 2015 used, and have no idea who drove it before me.

I suspect Transmission, Torque Converter lock-Up, or possibly CV joint (Inner). Any Thoughts?

This is a sudden acceleration that some fly by wire vehicles have been suffering from. Think of the Toyota Prius. Your throttle is electronically controlled and the PCM (Powertrain Control Module) takes a position reading from your foot pedal to know what you intend for your car to do. Unfortunately this system creates the possibility for problems such as you are having. Your transmission is also electronically controlled. In short, for some reason your car believes you want it to accelerate like your driving a Corvette.

You need to have your car diagnosed by an experienced technician. It will require an advanced level scan tool and a technician with experience with throttle control systems. This sounds like it is intermittent, so be prepared to give your technician extra time to figure this out. Intermittent problems can be difficult to recreate, making diagnosis very difficult.

In addition, this isn’t likely caused from how you drive your car. Failures happen just like a light bulb burns out. It just does when it is its time. Hopefully there is a Check Engine Light that indicates there is a code stored. This will often contain freeze frame data that can be used to understand what is occurring.

I recommend having your car looked by a qualified technician, such as one from YourMechanic, who can diagnose your car with a scanner to pinpoint the issue and help you fix it accordingly.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 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
  1. Home
  2. Questions
  3. When you slow down then re-accelerate..sounds like severe downshift.

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: My Chevy starts, switch gears, moved about 5 feet, started to make a clanking noise and would not move forward or reverse.

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...

Q: 2005 Chrysler 300C changed battery and alternator. Car started, ran, and then battery light came on. Shut car off and wouldn't start.

Hi. There is a couple of things that could be wrong here. The battery or alternator that was just installed could be defective. Theses parts need to be tested for proper operation. There also could be a fuse, fusible link,...

Q: Overheating

It sounds like you may have a blown head gasket. I would suggest performing a leak down test to see how each cylinder responds to a loss of pressure (if any). This should help to eliminate the guess work involved...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.