Q: Car shakes while in idle and doesn't want to accelerate

asked by on November 26, 2016

My spark plugs look wet but its not oil just left the shop they said my head gasket is ok... Do you think the spark plugs are wet from me keep trying to start my car ? What will cause the car to have problems starting and shaking while in idle and less acceleration

My car has 100000 miles.
My car has an automatic transmission.

Idle Control Valve Replacement $162.54 - $1028.01 Get a Quote

The spark plugs are wet from trying to start the vehicle which is a good sign because this means that the motor is getting fuel. When the motor struggles to idle, this is generally a result of things like low fuel pressure or a dirty or faulty idle air control valve. The idle air control valve reads the air intake as it is mixed with fuel prior to being injected into the engine at low speeds and at idle. As this valve is controlled by the vehicle’s computer, it will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage. When you accelerate, the engine RPM increases, and as you let off the gas, the RPM slowly returns to the normal idling speed. When the engine RPM drops below the normal range of 750-800 RPM (for most cars), this often times will cause the engine to stall indicating a dirty or faulty idle air control valve. There is a brief transition period between idle and acceleration in which the idle air control valve no longer functions as it’s purpose is to regulate idle speeds and deceleration. The struggle to accelerate may suggest other fuel delivery issues such as dirty or faulty fuel injectors. I would recommend having an expert from YourMechanic come to your location to diagnose and repair your idle air control valve.

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

What does it mean if the Supplemental Restraint System light in the dash comes on?
Your car is equipped with a supplemental restraint system (SRS). This includes your air bags, as well as seat belt components and more. If the controlling computer notices a problem with the air bags, the front passenger sensing system or...
Engine and steering making a weird noise
It sounds like you may be having a power steering system fault. The most common cause of this is a power steering fluid leak or a power steering pump failure. With the power steering causing the vehicle to be hard...
Car won't turn over but has new battery
YourMechanic next door was most likely correct and you have a problem with the key anti-theft system disabling the vehicle. You will either have to have a specialized locksmith come to you, program the key and make new ones, or...
Loose emergency brake lever
Yes, this is a safety issue. This means the parking brake may be broken, installed incorrectly, or out of alignment. This also means the brake may not be working to its full potential, or at all. The parking brake lever...
car overheated.fixed cylinderhead gasket replaced sparks n wires cant get it running
Hello, thank you for writing in. When the engine overheats to a certain point, there is damage done to the engine that is irreversible. The biggest concern is that inside of the engine, the pistons can heat up to the...
VDC OFF light comes on and SLIP light's comes on that is when you drive the car for 15 min or so and hesitate then go back to norm
Hi There, It sounds like you may have a faulty cam position sensor that may be causing the jerking reaction (which is normal when the cam sensor begins to fail), resulting in the traction control system to engage. The camshaft...
My 2007 Nissan Murano gas gage stays at empty and recently I started the car and I drove 3ft and it stopped what is going on?
Hi Brittany. Thanks for contacting us today. If the fuel sensor is not working on your Nissan, it may or may not be the cause of the acceleration problems you are having. In most cases this type of symptom is...
2004 lexus es330. check engine, VSC and TRAC OFF warning lights on
I would recommend having your vehicle inspected by a qualified professional to determine which check engine light codes are stored in your vehicle system. Once this has been done the mechanic and have a better indication of what the vehicles...
At first my brakes lights went out. Not a fuse or bulb. Than it wouldn't start. We jumped the car and now it surging.
What you have described are possibly all electrical problems but it is not clear if they are interrelated, that is have a common cause. Initially, though, the battery should be load tested (https://www.yourmechanic.com/services/battery-is-dead-inspection) and the battery us faulty install a...

Related articles

Symptoms of a Bad or Failing Distributor O Ring
If your car has a distributor, common signs the o-ring must be replaced include oil leaks and engine performance issues.
Symptoms of a Bad or Failing Exhaust Gas Recirculation (EGR) Tube
Common signs include rough idle, rattling noises from the engine, and the Check Engine Light coming on.
Understanding the Mercury Intelligent Oil Life Monitor and Service Indicator Lights
Car symbols, or dashboard lights, are a car service reminder. The Mercury Intelligent Oil Life Monitor indicates when and what service your car needs.