2014 Jeep Cherokee with check engine light on. Our customer reported the engine was running “rough” and shook when accelerating. We had no maintenance records for this vehicle and the owner could not remember when or if the spark plugs had been replaced.
Problem
2014 Jeep Cherokee with check engine light on, engine running rough and vibrating during acceleration, poor engine performance, and a lack of power.
Diagnosis
When our Jeep technician drove the vehicle into our shop they noticed that the Check Engine Light was on, the engine was running rough, and had a misfire condition on at least one cylinder. The technician checked the engine management computer with a scanner and found an engine error code indicating an engine misfire on cylinder #4. Further testing showed that the #4 ignition coil was not functioning.
We had no maintenance records for this vehicle, and the owner could not remember when the spark plugs were last replaced. The technician removed the spark plugs and found they were very worn and needed replacement. The valve cover seals were leaking and the spark plugs were coated with burnt oil which may have contributed to the misfire and failure of #4 ignition coil.
The technician recommended replacing the four spark plugs, all four ignition coils, and the valve cover gasket and seals.
We sent the vehicle owner a digital inspection report with a detailed description of what the technician found, supporting photos, and a detailed repair estimate. The customer approved the repair and we got to work.
Cause
Spark plugs wear out with use. They are considered a maintenance service like an oil change. The electrodes where the spark is generated operate under extreme temperatures and pressure in the engine cylinder and are constantly being worn away. This electrode erosion causes the gap the spark has to jump to widen, increasing the load on the ignition coils as they struggle to create a spark. This Jeep had 118k miles on the odometer and the spark plugs look to have never been replaced. The excessive spark plug gap most likely overloaded the ignition coil and caused it to fail. In this case, all four ignition coils should be replaced as they were all stressed by the worn condition of the spark plugs and would most likely also fail soon.
Driving conditions and the age of the vehicle affect the life of spark plugs. The factory-specified spark plug life of 100k miles is under optimum driving conditions. If a vehicle is used mostly for short-trip city driving like this SUV, the life of the spark plugs can be significantly decreased. Also, as the vehicle ages, it will start to burn engine oil, significantly shortening the spark plugs' life. It is common for spark plug life to decrease as the vehicle ages.
The type of spark plug can also greatly affect spark plug life. Inexpensive spark plugs have a maximum expected life of 30k miles. High-quality Iridium spark plugs can last as long as 100k miles. But there are many factors that affect spark plug life. We recommend replacing the factory installed Iridium spark plugs at a maximum of 100,000 miles, and thereafter replace them every 50,000 miles.
Not removing spark plugs for extended periods can result in the spark plugs becoming seized into the cylinder head. The spark plugs are very fragile and can break during attempted removal if they are seized into the cylinder head. Most cylinder heads are aluminum and the spark plug hole threads can be striped out if the spark plugs become seized.
Also, spark plugs can become loose from the repeated hot and cold cycles as the engine warms and cools. When combustion gases leak past the loose spark plug threads carbon deposits can build up and prevent the spark plug from being removed. There is a high risk of the seized spark plug breaking when removal is attempted.
If spark plugs are not removed periodically, they can seize into the cylinder head. This can often require disassembly of the engine to remove the seized spark plug and repair the threads in the cylinder head. Many times the cylinder head will need to be replaced.
A valve cover oil leak can cause missfire on some engines. The oil will burn onto the hot spark plugs and the ignition spark will travel through the burnt oil contamination rather than jump across the more difficult excessive spark plug gap.
Repair
The vehicle owner decided to follow our recommendation to replace the spark plugs, all four ignition coils, and replace the valve cover seals and gasket.
Our Jeep technician cleaned the leaked oil from the engine, replaced the valve cover seals and gasket, installed the new spark plugs after checking they had the correct spark gap, and installed four new ignition coils.
To ensure the problem was solved, the technician cleared the previous engine management computer error code, test ran the engine, did a follow-up diagnostic scan test to check that the ignition problem was fixed and that the engine was operating correctly.
The engine ran smooth with no error codes so the owner was contacted and told their Jeep repair was completed and was ready to be picked up.
Cost
How much does it cost to replace spark plugs in a Jeep Cherokee?
How much does it cost to replace 2014 Jeep Cherokee spark plugs?
How much does a 2014 Jeep Cherokee tune-up cost?
Jeep Cherokee Spark Plug Replacement Cost Estimate
Note: A 2014 Jeep Cherokee tune-up cost will depend on the engine the vehicle has. The V-6 and V8 engines have more spark plugs and ignition coils than the 4-cylinder engines, so additional parts and labor costs for those engines.
The national average for Jeep Cherokee Spark Plug Replacement cost is between $229 and $301. Labor costs are estimated between $138 and $174 while parts are priced between $91 and $127.
The price varies depending on the repair shop's location within the country, vehicle year, make, model, options, and the quality of the replacement parts.
Diagnosis, labor, and additional parts required for related problem repair, shop supplies, environmental and disposal fees, and taxes are not included.
Tips
Replace spark plugs at the factory recommended mileage to prevent damaging the ignition coils.
If one ignition coil fails replacing all ignition coils simultaneously is your best value. The labor to replace a single ignition coil at a later date can equal the cost of installing four new ignition coils.
Repair engine valve cover leaks as soon as possible. The burnt oil will short-circuit the spark plugs.
FAQ
How do I know if Jeep spark plugs need replacing?
8 Signs Jeep Spark Plugs Need Replacing:
- 100,000 miles since the original spark plugs were replaced.
- 50,000 miles since replacement spark plugs were last changed.
- Fuel economy decreases.
- Decreased power, slower acceleration.
- Rough engine idle.
- Engine misfire.
- Difficulty starting.
- Check Engine Light Warning.
Note: Spark plug replacement is a regular maintenance service. Check your vehicle owner's manual for the Jeep Cherokee spark plug replacement interval as every Jeep year, model, engine size, and option package can be different. Your driving conditions will vary on how often spark plugs should be replaced. An experienced Jeep technician can recommend the best spark plug replacement mileage for your local conditions and Jeep use.
Why is replacing Jeep spark plugs so expensive?
Modern vehicle design and high labor costs.
Modern vehicle engine compartments are very compact. Often many accessories and covers must be removed from the engine to access the spark plugs. Each ignition coil must be removed before the new spark plugs can be replaced.
Jeep Repair Shop in Ann Arbor, MI
Contact Abbott Street Auto Service for Jeep tune-up service and repair in the Ann Arbor, Michigan area. Our Jeep technicians have the skill and experience to correctly diagnose and repair your Jeep Cherokee problems. We are Jeep service specialists.
You can trust your Jeep service to Abbott Street Auto Service. Located in Ann Arbor, MI, Abbott Street Auto Service also serves the surrounding areas, including Pittsfield, MI; Ypsilanti, MI; Saline, MI; and Dexter, MI.