How Much Does a Cylinder Misfire Cost?


Written by:  Howmuchisit.org Staff
Last Updated:  August 9, 2018

 

A cylinder misfire can happen for various reasons, and when it happens, it generally causes the car to run rough, jerk or buck.

With every spark plug electronically timed to fire at an exact instant to deliver the engine’s specified output, one slight change can cause this so-called “misfire.”

Repairing a misfire isn’t as straightforward as other car repairs as the problem can be due to a variety of reasons, including worn-out spark plugs, a vacuum leak or worn valve seals, for example.

If your engine were to misfire, it’s important to bring it to a mechanic as soon as possible, as the problem will worsen over time, often damaging the internal components of the vehicle.

smoke em if you got em by frankieleon, on Flickr
smoke em if you got em” (CC BY 2.0) by frankieleon

How much does a cylinder misfire repair cost?

As mentioned, a cylinder misfire can happen due to a few reasons, and to make things simple, we created a table to show you exactly what repairs may be required to fix the misfire condition.  As you can see, the costs can greatly vary, depending on the reasons why the misfire is happening in the first place.  With so many variables, you could spend as little as $150 for new spark plugs to as much as $1,000+ for a vacuum leak.

What May Cause the Engine MisfireAverage Estimate
Bad fuel delivery$200 to $1,000 or more, depending on the reason for the bad fuel delivery
Bad spark plug wires$100 to $300
Broken piston rings$1,500 to $3,000
Broken valve springs$450 to $650
Carbon or oil-fouled spark plugs$100 to $250, depending on the costs of the plugs and local labor rates
Faulty ignition coil$150 to $250
Fuel injector$275 to $400
Vacuum leak$200 to $800

For older vehicles, YourMechanic claims the culprit is almost always the ignition system as these vehicles often lack the sophisticated sensors which can cause the misfire.  As for modern vehicles, misfiring will be accompanied by a “check engine” light, telling you exactly which cylinder is to blame and whether it’s a problem related to the injector service the cylinder or the systems responsible for the ignition spark.  These codes can read as a cylinder 1, 2, 3, 4, 5 or 6 misfire, and the numbers often refer to the spark plug in question.

On this Reddit thread, a forum member’s check engine light had come on due to a cylinder 1 misfire.  The local mechanic he had gone to quoted $609, excluding the $80 diagnosing cost.

Cylinder misfire repair overview

Common reasons an engine may misfire can be due to a faulty spark plug, faulty ignition coil, broken piston rings, burnt out valves, broken valve springs, a worn out camshaft or the fuel injector isn’t working.

To diagnose the issue, a mechanic will first use their code reader to see what the problem is related to.  From there, if the spark plug may be to blame, a mechanic will run the engine at an idle speed to see if the spark plug can hold its own, followed by removing the leads from the coil pack to see which wire may be to blame.  If the ignition and spark plugs weren’t the issue, then the injectors will be closely examined to see if it needs to be replaced.  Using a multimeter, the mechanic will check the resistance value to read the value in Ohms.  If read outside of the specified values, then they may need to be replaced.  Lastly, the fuel pump, which can cause an engine to misfire, could often be the blame.  This can simply be checked via a fuel pressure check.

Engine misfire causes

When driving, you may hear more than one cylinder misfiring, similar to a popping or sneezing-like sound.  Backfiring is a common sound heard as well.

Along with louder noises, a misfiring engine can produce a foul smell, similar to gasoline, but with a combination of coolant and engine oil.  If you do notice a distinct smell, this could be due to damaged cylinder walls.

A loss of power, often caused by the vibration of the engine, can cause the internal parts to rotate unevenly, causing unnecessary wear and tear.

Large clouds of black smoke coming from the exhaust could also be a sign requiring attention immediately.

How can I save money?

While it may be too late, an engine misfire can be prevented as long as you follow through with your scheduled maintenance in your manual.  Keep the engine tuned to the manufacturer specs to help uncover any problems which may arise in the future.

Any sign of a misfire should be taken care of immediately to prevent problems from arising in the future.  Waiting too long can lead to a much higher repair bill than expected.


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Less Expensive $1 $1.5K $3K $5K $6.5K More Expensive $8k

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