Q: only passenger side plug is carbon build up driver side is clean change plug doing same thing

asked by on August 04, 2017

my car was hesitate when go up hill and start to go change plug and wire only passenger side plug was heavy carbon build up driver side was clean burn after 100 mile car was acting up same problem check plug only passenger side plug carbon build up again

My car has 90000 miles.
My car has an automatic transmission.

Oil/Fluid Leak Inspection $79.99 - $99.99 Get a Quote

Hello, thank you for writing in. The most common cause of carbon build up on the spark plugs is unburned fuel, also known as "running rich". Despite the assumption that the injectors are to blame, it usually has more to do with how the spark plug is firing. Since it has happened to two separate sets of plugs, you are concerned with the ignition circuit at that side or plug. The coils and wires are the first to rule out. Oil being burned in the engine can also cause extra carbon deposits. If the ignitions system checks out, start looking for signs of an internal oil leak. For more help with diagnostics and repairs, contact our service department to schedule an appointment.

If only one side of the motor is clogged with excessive carbon build-up, it may represent a lean mixture issue with the fuel injection system. Unless you are experiencing loss of power, fuel mileage of the engine is running extremely hot, I wouldn’t worry about it. If you experience those symptoms, have a professional mechanic inspect the fuel system for issues.

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

Will a fender from a coupe fit a sedan?

Hi there. In most cases, the front half of the vehicle is similar in dimensions for both sedans and coupe's of the same model. However, what can vary is the location of bolt holes and brackets for installation. In order...

Theres grease oozing from the inner cv joint

The CV joint boot is leaking out its lubricant grease. This is most commonly caused by a joint rubber boot is cracked or torn and also the clamps that hold the boots in place can be loose or out of...

Cylinder Deactivation System in Bank 1

The diagnosis and repair of this type of problem will require the work of a professional. The cause may be as simple as a low oil level or the need for an oil change or as complicated as the need...

Muffler is loud and the van jumps when in idle. When it jumps the muffler makes a puffing noise and smells.

This may be related to a failing catalytic converter or potentially a dirty or failing idle air control valve. The idle air control valve reads the air intake as it enters the motor and relays this information to the computer...

There's a bad smell after I rebuilt the transmission

Hi, and thanks for contacting YourMechanic. What seems to be happening is that your vehicle is having a parasitic draw (power drain with key off) within the electrical system of the transmission. Check the harness to the transmission and look...

Noise when turning to the left

It's difficult to say without inspecting the vehicle firsthand just what the noise is. A worn or damaged wheel bearing will make a rotational growling noise that often gets worse when turning. To check for a bad wheel bearing, lift...

crankshaft position sensor problem

No it will not work. Do not try and install it since it will not fit or work. If you start a quote for a crankshaft position sensor replacement with YourMechanic, the right part will be found for your Jeep....

Related articles

The Best Used Cars to Buy If You're a Rock Climber
If If you’re a rock climber, you want a vehicle that gets you where you need to go, even if the terrain gets rough. You may be living out of your vehicle at times, so you also want a rig...
The Best Used Cars to Buy If You're a Skier
When When summer ends, skiers start thinking about hitting the hills, and that means having to contend with winter driving conditions. Not just any vehicle is going to get the job done. We have evaluated several used ski-worthy vehicles, and...
What Are the Best Spark Plugs for Normal Use?
Spark Spark plugs are essential components of your ignition system. They’re responsible for supplying the spark that ignites fuel and starts the combustion process. However, not all spark plugs are created equal. You’ll find “normal” plugs on the market, but...