How To Fix Diesel Engine Misfire?

Randy in Alabama has a question: What are some possible causes of diesel engine misfiring, and how do you remedy it?

Engine misfires are prevalent in diesel engines, but the good news is that they are usually a simple problem to diagnose.

Misfires in automobiles are a completely different beast than misfires in diesel engines. Diesel engines use compression to ignite the fuel, whereas gasoline engines use a spark from an ignition system. When it comes to automobile misfires, the ignition system is the first place to look. Inspection of the ignition wires, spark plugs, distributor cap/rotor components, and ignition coil are the next steps in diagnosing the problem. Because the components stated above wear down over time, the spark generated for ignition is frequently not correctly transported. The engine will not be able to turn over if the air/fuel mixture in the combustion chambers cannot be ignited.

1. Make certain you’re using high-quality diesel fuel. Examine the diesel fuel to ensure it is free of pollutants such as water, dirt, or oil.

2. Examine the service log for the fuel system. Replace the fuel filters as needed, and use a fuel water separator to drain water from the system.

3. After you’ve double-checked that the engine is in good working order and that the fuel filters have been replaced, look for any broken or leaking high-pressure fuel lines. Although you may pressure test the fuel line, most leaks are visible and easy to locate.

4. Check for low fuel supply pressure in the fourth step.

5. Inspect the gasoline line and transfer pump for bends or kinks.

6. Inspect the gasoline tank for a clogged suction pipe or a plugged suction hole.

7. Inspect the fuel system for air and fuel pressure.

8. Replace the fuel filters if the pressure is less than what is specified.

9. Check for a free-moving poppet in the return valve; if it is low, replace the transfer pump.

10. If none of the foregoing diagnoses the problem, there are four further possible causes of engine misfire:

The good news is that engine misfires are rather common and are not indicative of a more significant problem with the diesel engine. Each engine is unique, and Mack E-7 or E-Tech engines, for example, have a thicker fuel line than a Detroit Series 60 or a CAT 3406E. The problem with a Mack engine could be with the injectors rather than the fuel line. It’s critical to inspect each engine component individually to rule out problems one by one. Begin with the simplest problem and work your way up. If your engine continues to misfire, please contact a diesel parts specialist for assistance.

What would cause a diesel to misfire?

When the ignition in a diesel engine fails, a misfire occurs. Premature, delayed, or incomplete combustion are all examples of poor ignition. It’s vital to keep in mind that misfire doesn’t happen at all RPMs. It’s possible that it’ll happen when you’re not doing anything.

How do you diagnose a diesel misfire?

Rough running, a decrease of power and fuel economy, and the unwanted check-engine light flashing on the instrument panel are all common signs. Many system faults can be the cause, but let’s look at the three most common sorts of misfires.

What does a diesel misfire sound like?

Your engine produces a distinct and audible sound when it misfires. Even if you’re not an expert on car sounds, you’ll be able to tell when this occurs. You’ll either hear it coming from inside or outside the vehicle, or you’ll notice a sound coming from the exhaust. So, what does it sound like when an engine misfires?

A popping, sneezing, pounding, chuffing, or backfire sound is the most popular description of an engine misfire, which usually occurs between 1,500 and 2,500 rpm. When unburned gasoline left the cylinder and is pushed out during the exhaust stroke, it is ignited by the spark of the following cylinder, causing it to erupt out through the exhaust system, resulting in the sound.

If your car sounds like it’s straining, you’re probably dealing with an engine misfire. To hear it from inside your car, you may need to turn off the radio and close the windows. You’ll notice that your engine sounds different than usual if you listen intently. A change in engine sound could indicate that one of the cylinders isn’t working. Other signs of an engine misfire, such as the car lacking power under full throttle, can prove this.

How can I find out what is causing my misfire?

As previously stated, a misfire occurs when one or more cylinders fail to ignite properly or at all. Misfiring occurs when the combustion process, which involves the ignition of the air-fuel mixture that enters the cylinder, is disrupted in some way.

  • a failure of a component in the ignition system (including abnormal ignition timing advance),
  • Key valves or sensors that the automobile computer utilizes to calculate the correct air-fuel ratio are malfunctioning.

Misfires caused by a lack of spark, rather than a lack of fuel, are especially dangerous because unburned fuel can enter the exhaust system and catalytic converter.

If this happens, the raw fuel will eventually ruin the converter, necessitating immediate attention to the problem. If a misfire threatens to destroy your catalytic converter, the Check Engine Light (CEL) or Malfunction Indicator Light (MIL) will begin to flash on most modern vehicles.