A misfire code or misfire condition can have one of several root causes. For example: bad spark plug wires, a bad fuel injector, low engine compression. Unfortunately, this list of 'possible' bad components can grow quite a bit, which makes it seem like it's almost impossible to find the cause of the misfire or rough idle condition on your Chrysler 2.0L or 2.4L equipped vehicle.
The good news is that testing a misfire code, or misfire codes, or a rough idle condition is not that hard and it's something you can do!
In this tutorial, I'm going to explain in some detail the most common causes of misfires and misfire codes (P0300, P0301, P0302, P0303, P0304) and more importantly, I'm also gonna' offer you a simple diagnostic strategy that I'm certain will help you 'nail down' the cause of the misfire condition, misfire code, or rough idle condition your Honda is experiencing.
Let's get started!
Contents of this tutorial:
What Is A Misfire Condition?
In layman's terms, a misfiring cylinder is a cylinder that's 'dead', either because it's missing fuel, or spark, or air.
Since the 2.0L and 2.4L engines have only 4 cylinders, having just one of those cylinders misfire will have pretty obvious consequences due to the fact that the engine in your Chrysler is running on only 3 cylinders. If the engine in your car has one or two misfiring cylinders, you'll have one or more of the following symptoms:
- The Check Engine Light will be on.
- One or more misfire codes (P0300-P0308) will be stored in your Chrysler's PCM memory.
- P0300 Random Cylinder Misfire.
- P0301 Cylinder #1 Misfire.
- P0302 Cylinder #2 Misfire.
- P0303 Cylinder #3 Misfire.
- P0304 Cylinder #4 Misfire.
- Sometimes, even tho' the engine is suffering a bonafide misfire, no misfire codes are registered and no check engine light (CEL) comes on.
- Lack of power upon acceleration.
- Smell of unburned gas exiting the tail pipe.
- Rough idle and may stall.
- Cranks but does not start.
- Will not pass the emissions tests.
- Bad gas mileage.
Although the misfire codes don't tell you what exactly is the cause of the misfire or rough idle condition, there is a way to find out exactly what is causing it.
One of the most important things you need to know, to successfully diagnose a misfire or rough idle condition, is what causes a misfire. Let's go to the next subheading and find out.
What Causes A Misfire Condition?
Each engine cylinder needs 3 things to be able to produce power. In a nutshell, these 3 things are:
- Air
- Fuel
- Spark
It's when one of these three things is missing from the mix that the engine in your 2.0L or 2.4L Chrysler starts to misfire. Let's look into more specifics:
Ignition System: The ignition system is responsible for the production and delivery of spark. The ignition system is usually the culprit behind most misfires.
The usual suspects (that cause a misfire) are:
- Bad spark plugs.
- Carbon tracks on the spark plug and spark plug boot.
- Bad spark plug wires.
- Bad ignition coil pack.
- Oil dripping (from the valve cover) onto the spark plugs and COP ignition coil boots.
Fuel System: The fuel system is responsible for the delivery of fuel. If fuel is missing from any one specific engine cylinder, it will misfire.
Fuel system problems could include some of the following:
- Bad fuel injectors.
- Broken fuel injector connector (this is a very, very common problem).
- Electrical short in the fuel injector wires that are keeping the fuel injector pulse signal from reaching the fuel injector.
- This is usually the result of human error and after a major mechanical repair where the wiring harness was damaged.
- Bad fuel injection computer not pulsing the fuel injector (this is a very rare condition, but it happens).
- Bad fuel pump.
Engine Mechanical Condition: The pistons and cylinder head valves are the ones that draw air into the engine. Usually all cylinders wear out evenly but every now and then, either thru' lack of maintenance or some mechanical problem, you'll have one or more wear out at an accelerated pace.
To make the long story short, those cylinders (with accelerated wear and tear) to produce a less than average compression value that will cause a misfire condition.
Other issues, that can not be overlooked are vacuum leaks.
What Tests Can I Perform To Find The Cause Of The Misfire Condition?
Now that you have an idea of what are some of the causes of a misfire condition, you might be asking yourself, 'Where should I start?'.
In this section, I'm gonna' offer you a simple diagnostic strategy that should help you find and resolve the root cause of the misfire or 'dead' cylinder on your 2.0L or 2.4L Chrysler.
STEP 1: Identify the dead cylinder. This usually entails connecting your scan tool to your vehicle and reading the misfire diagnostic trouble codes. Then by matching the misfire code to its engine cylinder using an illustration of the engine cylinders.
In many cases, the PCM does not give you any misfire codes, even though the engine is suffering a bonafide misfire. In these cases, you'll need to do a manual cylinder balance test by unplugging one injector at a time (to see which one has NO effect on the engine's idle).
The fuel injector that does not worsen the engine's idle when unplugged, tells you that that specific cylinder is 'dead'.
STEP 2: Test the ignition system . Since the majority of misfires are caused by a failed component in the ignition system, it's important to make sure that the misfiring cylinder is getting spark. You should:
- Perform a spark test (using a dedicated spark tester) on the spark plug wire of the cylinder that the misfire code is accusing of being dead.
- Testing for spark with a spark tester is the most important first test since you'll know right away if the misfire is due to a lack of spark.
- Check to see if the spark plug boots and spark plugs are swimming in engine oil from a leaking valve cover gasket.
- If you got spark from your spark tester (from the cylinder the misfire code is accusing of misfiring), the next step is to remove the spark plug or spark plugs (of the affected cylinders) and check them for wear and tear, carbon tracks, anti-freeze, etc.
- If you get no spark, then the next step is to check for spark directly on the ignition coil pack tower.
- You can find all of these ignition system tests here:
- How To Test The Coil Pack (Chrysler 2.0L, 2.4L) (at: easyautodiagnostics.com).
- Carbon Tracks Are A Common Cause Of Ignition Misfires (at: easyautodiagnostics.com).
STEP 3: Test the fuel injectors. If the ignition system is not the cause of the misfire, then the next step is to check the fuel injectors.
You'll need to:
- Resistance test each of the 4 fuel injectors.
- Do a Noid light test of each one to make sure the PCM is pulsing them (activating them).
- You can find the fuel injector tests here:
STEP 4: Test the compression of each engine cylinder. Other tests that should be done, if the ignition system and fuel injectors check out OK are:
- Engine compression test.
- Checking for vacuum leaks.
- You can find the engine compression test here:
The above list of steps may seem/sound like troubleshooting a misfire is a complicated thing but it really isn't. Depending on your level of 'wrenching' experience, this is something that you can accomplish without taking it to the shop.
What Tools Do I Need To Test The Misfire Code(s)?
Finding the exact cause of the misfire codes or misfire condition is possible with the proper tools. Without them, you won't be able to diagnose/troubleshoot those issues on your 2.0L or 2.4L Chrysler car or mini-van.
Depending on what the root cause of the misfire is, you may need several tools. Most of these you can buy online, none of these will break the bank and I'll make some recommendations on them. Here's a guide to some of the basic tools that can be and are used:
- Ignition System Tests:
- Spark Tester.
- Multimeter.
- Test Light.
- Fuel System Tests:
- Noid Light.
- Fuel Pressure Gauge.
- Multimeter.
- Engine Mechanical Tests:
- Compression Tester.
Now of course, you'll also need basic hand tools like: screw-drivers, ratchet wrenches, sockets, etc. You'll also need a generic scan tool to retrieve the diagnostic trouble codes (DTCs) from the computer's memory.
Keep in mind that using the right tool for the job will save you time, frustration, and /or keep you from damaging the component that you're testing.
In Conclusion
Testing a misfire or a rough idle condition on your 2.0L or 2.4L Chrysler equipped vehicle can seem hard but if you follow the above troubleshooting steps, you'll be able to avoid replacing parts that are good.
Take advantage of the other tutorials in the 2.0L or 2.4L Chrysler section since I've written all of them from practical every day experience and tailored for the home mechanic.
You can find a complete list of tutorials here: Chrysler 2.0L, 2.4L Index Of Articles.
Here's a small sample of the tutorials you'll find in the index:
- P0108 MAP Sensor OBD II Trouble Code (Chrysler 2.0L, 2.4L).
- How To Test The Fuel Pump (Chrysler 2.0L, 2.4L).
- How To Troubleshoot A No Start (Chrysler 2.0L, 2.4L).
- How To Test For A Blown Head Gasket (Chrysler 2.0L, 2.4L).
- How To Test The Engine Compression (Chrysler 2.0L, 2.4L).
If this info saved the day, buy me a beer!
