6 Fixes for Your Misfiring Truck
A misfiring engine robs you of power, and fuel economy, not to mention all the unburned hydrocarbons polluting the air. Check these simple things and be back running on all cylinders in no time.
1. Failing Coil Packs
A gas powered truck with a bad ignition coil pack should give you a check engine light, as well as exhibit a rough idle and cough running under load. You can either head to an auto parts store or your local dealer to read diagnostic trouble codes indicating misfiring coils, or, if you are a responsible Ford truck owner, use an OBD-II reader to check them yourself. These codes will reveal which cylinder is misfiring, and swapping the suspect coil pack for another one on the motor that reads good will tell you if the coil itself is bad. If it is you can change it out yourself, and new coil packs are around $40. Refer to this helpful How-to guide to get the job done right.
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2. Clogged Fuel Filter
If you notice your gas or diesel powered truck sputtering and misfiring during sustained cruising, you'll want to check for a clogged fuel filter. An accumulation of dirt or rust from the fuel tank, or contaminated fuel at a gas station, will cause clogging here. Simply replacing the filter should remedy the misfiring issue, but if it persists then you may have clogged fuel injectors. Keep reading to troubleshoot this next possible culprit.
Related articles:
- How to Replace the Fuel Filter in Ford F-150 - Ford-trucks.com
- How to Replace the Fuel Filter in Ford F-250 - Ford-trucks.com
3. Bad Injectors
If the fuel filter is clogged, the injectors may follow suit and become clogged themselves. Clogged injectors mean poor spray patterns which mean uneven fuel mixture, flame propagation, and low fuel flow. This issue will usually throw a diagnostic code, so have your trusted OBD-II reader ready. To diagnose the troublesome injector, you can troubleshoot it by swapping the injectors between cylinders and determining whether or not the misfire follows a particular injector. If you find that an injector is faulty, it's recommended to have all of them cleaned and flow matched at the same time. They've likely all got the same mileage on them, so it makes sense that if one fails, another is not far behind.
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4. Failing Spark Plugs
These days, spark plugs are less likely misfiring culprits, as computer controlled fuel injection and higher coil power has all but eliminated fouling. They are long-lived components and should only have to be changed around 100,000 miles. Still, if your engine is not running well, your injectors may cause the plugs to foul, and the useful lifespan of the spark plugs will very much be shortened. Check that no antifreeze is leaking into the spark plug tubes, or getting into the cylinder via a leak in the intake manifold, as that will cause engine misfiring. Since spark plugs are easily accessible and removable, there's no reason to not make the effort to replace them yourself with help from our guide below, of course.
Related article: How to Replace Spark Plugs in F-150/F-250 - Ford-trucks.com
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5. Low Cylinder Compression
Engine misfires can be caused by cylinders with low compression due to a blown head gasket, a worn cylinder wall, cracked piston rings, stuck valve, or worn valve seats. Proper cylinder compression is necessary, along with the correct air/fuel mixture, and the spark from the ignition, to complete the combustion process. A compression test gauge threaded into the spark plug hole should tell you how much each one it pumping. All of the cylinders should be about the dame reading, with only about a 10% variation maximum. If one of them is bad, you'll have to tear into the motor and examine the cylinders for any signs of wear or damage, then fix or replace the bad parts.
For more help diagnosing and repairing issues with your truck, check out the how to section of Ford-Trucks.com
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6. Clogged or Melted Catalytic Converter
A clogged or melted catalytic converter, or one that's experiencing carbon buildup as shown in the image above, will cause back pressure from the exhaust which disrupts the combustion process. This, in turn, strains the engine which leads to misfires. The reason for a melted or clogged catalytic converter is an engine that runs rich and sends unburnt fuel to this component where it does burn.
Related articles:
- How to Replace the Catalytic Converter in F-150 - Ford-trucks.com
- How to Replace the Catalytic Converter/Diesel Particulate Filter in F-250 - Ford-trucks.com
For maintenance and repair guides for your Ford truck, browse our technical How-to articles right here at Ford-trucks.com!