Q: Reduced engine performance that smooths out after 40 MPH until acceleration.

asked by on December 17, 2015

Vehicle runs roughly and has a read out thats says reduced engine performance. Initailly, the vehicle runs rough at 40 mph, then smooths out until I try to accelerate.

Engine hesitates during acceleration Inspection $94.99 - $114.99 Get a Quote

Hello, being that the engine and transmission are computer controlled, a scanner needs to be connected to retrieve codes. If there are no codes present the technician will be able look at data retrieved by the scanner and come to a possible solution. When symptoms like this occur with the "reduced engine performance" message, the vehicle is going into limp home mode trying to protect the engine and or transmission from further damage. You should enlist the aid of a mechanic to inspect your engine.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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


Experienced Mechanic?

Earn up to $70/hr

What others are asking

Brakes not working correctly.
Do not drive your car in this condition, have a mobile mechanic come inspect your car to inspect the damage. (https://www.yourmechanic.com/services/brake-safety-inspection-inspection) The hydraulic master cylinder is the heart of your brake system, it provides flow to the brake calipers and...
Car shakes violently and 'check engine' flashes
Since you are only getting a misfire on cylinder number 3 specifically, this informs me that the cylinder ignition is not the problem. Since the engine has a coil pack that powers two cylinders at the same time and if...
Rpms won't drop.
It is possible you have a large vacuum leak or the idle air control valve is stuck in a position best suited for colder weather. A vacuum leak will allow unmetered air into the engine causing the computer will add...
shifting problems and the vehicle will not go backwards. Plus it will try to lunge forward in park.
Hi there. What could be the issue is the main valve to the transmission may have disconnected from the shifter lever on the side of the transmission. Raise up the vehicle and put it on four (4) jack stands. With...
Rear wiper arm
The rear wiper arm (http://lgcdn.morris4x4center.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/j/e/jeep-wiper-ramp_1676.jpg) is part of the collar that you are referring to. The arm and collar are made and molded together. Once you remove the retainer nut you can use a small puller to grab the arm...
My Buick LeSabre 1998 model misfires on cylinder #3.
Hi there. The fuel is warm when the level is low and when the fuel tank is filled up the fuel tends to get cooler than it was before. In general, the fuel is low dense when it is warm...
Car loses rpms and stalls
Hi There, The sloshing sound you are hearing is likely your radiator low on coolant. I would suggest having it flushed (https://www.yourmechanic.com/services/cooling-system-flush) to be sure there are no air pockets in it. The stalling you are referring to is likely...
vibration and shaking at idle. also very loud and noisy engine. replaced all motor mounts, spark plug components, and intake syste
Often noise is related to exhaust system leaks or internal failures in the exhaust such as loose baffles in the muffler. To rule out accessory drives and pulleys as a source of noise what you can do is momentarily run...

Related articles

What Does It Mean When My Car Is "Burning" Oil?
Burning oil is usually caused by leaking oil that burns up on hot engine or exhaust components. Fix leaking oil to prevent expensive car repairs.
How Long Does a Thermostatic Vacuum Sensor Last?
Winter Winter can make for tricky driving conditions - just starting up your vehicle can be a bit more of a chore. When the engine is cold, it takes a few minutes before it reaches optimal temperature and you should...
How to Determine Compression Ratio
Whether Whether you’re building a new engine and you need the metric, or you’re curious to know how efficient your car uses fuel, you have to be able to calculate the engine’s compression ratio. There are a few equations needed...