One of the most common problems that can occur is a vehicle that shakes when accelerating. If your Toyota Prius shakes during acceleration, this is something you should not ignore. While vibration can be annoying, it is often indicative of a serious problem.
speed is important
Vehicle speed is important when you feel a vibration. Different problems will occur when you drive at different speeds. If you have found that the problem only occurs when you accelerate your Prius, this really helps narrow down the problem. Vehicle speed can help even more.
For example, a vehicle thatshakes when brakingwill have almost no overlap of causes with a vehicle thatshakes when accelerating. For this reason, we have tried to include the most common speed associated with the various causes of horror listed below.
Toyota Prius shakes during acceleration: causes
There are a few reasons why your Prius shakes when you accelerate. Here are the most common ones. They are presented in a somewhat logical progression.
1. Failure
Vehicle Speed: A misfire can be felt at any speed, but is most noticeable at low revs.
A malfunctioning engine is one of the most common reasons why your Prius shakes when you accelerate. A vehicle's ignition system consists of spark plugs, coil assemblies, and perhaps spark plug wires. If it's an older model, it will have a distributor and coil instead of coil packs.
If any of these ignition components do not provide enough spark, your vehicle will stall. With one failure you will almost certainly get a Check Engine Light. Check the codes. You more than likely haveP0300(Random Misfire) or you will get P030X where the number of the failed cylinder is represented by X. For example P0301 is acylinder 1 misfire.
Diagnosis
If you diagnose a failure at home, start with the spark plugs. Do they appear to be in good condition?
On the left here you can see a dirty spark plug. This particular plug was from a 5 year old Honda with 60,000 miles. Modern vehicles can and do make dirty plugs, especially when cylinder deactivation technology is involved (as was the case in this example).
If you have a cylinder-specific fault code, there's an easy way to tell if it's the spark plug or the coil assembly. It's called the trade-off test. Here's how to do it:
- Check the fault code of that particular cylinder and note it down.
- Clear ECM trouble codes.
- Replace the coil assembly and plug wire (if present) with another coil.
- If the fault code "moves" to a new cylinder, you have found the problem parts. If it remains, replace the spark plug even if it looks good.
Here are some good resources with more detailed information:Bad spark plug diagnosis,Causes of spark plug oil
2. Bad motor mount
Vehicle Speed: A poor engine mount will be felt during direct acceleration. You should feel a vibration as you release the gas, although it may not be as strong.
The engine mount is responsible for connecting the Toyota Prius engine to the frame. It also needs to absorb a significant amount of shock. There are a few different types of engine mounts, but the most common type uses a rubber bushing to absorb vibration.
If the engine mount comes off, the vehicle will shake a lot when you accelerate. It could still get worse. A broken engine mount will allow the engine to roll under the hood and you will hear a screeching sound.
There is more than one engine mount on a vehicle. If one of them breaks, in addition to the extra vibration and shaking, it also creates extra stress on the other bases. Here's more aboutbad engine mountdiagnosis.
internal fixed connection speed
Vehicle Speed: If you have a damaged CV joint, it will likely be noticeable at all speeds. But it can be worse when cornering and accelerating hard.
The CV joint is responsible for sending power to the front wheels of front and all wheel drive vehicles. Most likely the inner CV joint is the part of the CV shaft that is damaged.
Most of the time, a bad CV joint is caused by a torn boot. The guard goes over the CV joint and keeps oil in and debris out. It is very easy to tell if the boot is bad. Just take a look. There will probably be grease all over the bottom around the boot. The boot shown above has a small tear.
transmission shaft
Vehicle Speed: When a universal joint or drive shaft fails, there is usually a certain speed at which the shudder is more pronounced. If you continue to accelerate, many times it will "go forward" and stop vibrating.
Rear-wheel drive and four-wheel drive vehicles use a drive shaft to transfer power from the engine to the rear wheels. The driveshaft is a simple tube that connects the transmission to the rear axle.
It is possible for the drive shaft itself to bend. It is much more likely that a universal joint is bad. The universal joint needs to change the direction something rotates.
See the chart below. As it wears, there will be play between it and the drive shaft, which causes shuddering during acceleration and constant shuddering at certain speeds. Here is onea little moreabout it if you suspect this is happening to your vehicle.
stuck brake caliper
Vehicle Speed: If you have caliper brakes, your Prius will shake more and more as you accelerate. You will also feel it on the steering wheel and it will probably pull left or right depending on which side the caliper sticks.
A stuck brake caliper can happen to any vehicle. This can happen for a number of reasons, such as the caliper piston sticking or a bent brake line. Most likely, you will need to replace the caliper. See more about how to tell if your Prius isthe brakes lock up.
Diagnosis
It's easy to tell if the caliper is bad.
- Said wheel will have a strong smell coming from it, soburning carpet.
- The steering wheel will shake.
- The vehicle will pull in one direction.
- The wheel in question will have more brake dust than the other wheels.
- The brake pad will probably be glass.
loose nuts
Vehicle Speed: Shaking and vibration should be felt at any speed. It will feel worse at some speeds and better at others. It depends on the vehicle, the wheel in question and how loose it is to know exactly what the speed will be.
Nuts can cause the vehicle to shake during acceleration. If you have any doubt as to whether or not they are fully tightened, you should take your Prius off the road as soon as possible and have it checked.
Diagnosis
Loose lug nuts usually appear after a tire change, rotation, or any other work recently done on the vehicle that would require the removal of a wheel. Take a torque wrench and tighten all four to factory specifications.
Tire balance or wheel misalignment
Vehicle speed: You are more likely to feel the vehicle shake as you increase speed. You shouldn't notice much below 30 mph.
Tire balance can cause the car to shake during acceleration. Tires use wheel weights to achieve "balance". This corrects any chatter that would otherwise occur. These weights may drop over the life of the tire. When this happens, the tire will vibrate.
Poor wheel alignment can cause uneven tire wear and vehicle shaking. It is very likely that the vehicle is misaligned if you have recently climbed a curb, hit a large pothole, gone too fast over a bump, etc.
Diagnosis
Take a look at your wheels. If you see a spot where the weight of the wheel was, that's a good indication that you've found the problem. You will see the other wheel weights. The outline of the missing wheel weight is obvious and not something you can easily miss.
A misalignment will manifest itself in tires that have not been properly worn. If the vehicle hasn't been aligned recently, you won't see any physical evidence looking at the tires. The mechanic of your choice can check your alignment for you.
Other engine problems
Vehicle Speed: Other engine problems are felt at any speed, but are most noticeable at low revs.
If your engine is not running well, you should check if the check engine light is on. There's a lot stored in the ECM that can tell you what's going on. Here are some of the problems that can cause a vehicle to jerk when accelerating and that can originate from the engine:
- vacuum leak
- MAF sensor ruim
- Fuel delivery problem
- Valves need adjustment
- Air and fuel mixture
- Clogged fuel injector
Any of these problems can cause the engine to shake. Although the list may seem daunting, if there is no trouble code associated with the items listed on your computer, it is unlikely to be the problem.
Here's more for onespraying machine.
Bottom line: The Prius shakes under acceleration
It is clear that there are a number of problems that can cause the steering wheel to shake during acceleration. We hope this article helped you narrow them down. If you have discovered the cause of your Prius jerking problem, please leave a comment below. You can help the next person who finds their way here. Good luck!