Chasing down a cylinder misfire can be frustrating —especially when it keeps coming back or doesn't set a clear code.
But if you take a step-by-step approach, you can zero in on the cause without wasting time, money, or replacing good parts.
In this tutorial, I'll walk you through the exact method I use to figure out if a misfire is caused by ignition, fuel, or a mechanical problem. Whether you're wrenching in your driveway or working in a shop, this process works.
Contents of this tutorial:
APPLIES TO: This tutorial applies to the following vehicles:
- 3.3L V6 Chrysler Town & Country: 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010.
- 3.3L V6 Chrysler Voyager: 2000, 2001, 2002, 2003.
- 3.3L V6 Dodge Caravan: 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007.
- 3.3L V6 Dodge Grand Caravan: 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010.
- 3.3L V6 Plymouth Voyager: 1996, 1997, 1998, 1999, 2000.
- 3.3L V6 Plymouth Grand Voyager: 1996, 1997, 1998, 1999, 2000.
What Is A Cylinder Misfire?
When we say an engine has a cylinder misfire, we mean that one (or more) of the cylinders isn't firing the air-fuel mix properly. That cylinder is basically "dead weight" —it's not contributing to power like it should.
Each cylinder needs three things to fire: spark, fuel, and compression. If even one of those is missing or weak, the cylinder won't fire right, or won't fire at all. That's a misfire.
When a cylinder misfires, you'll usually notice a combination of performance problems and a warning light on the dash.
- Rough idle.
- Hesitation or stumbling during acceleration.
- Noticeable loss of power under load.
- Check Engine Light flashing or staying on.
- Diagnostic trouble code (DTC) like P030X —where X is the misfiring cylinder (e.g., P0302 for cylinder #2).
Misfires aren't just annoying —they can cause engine or catalytic converter damage over time if ignored. That's why pinpointing the root cause fast (ignition, fuel, or mechanical) is key to saving time, money, and frustration.
How To Troubleshoot A Cylinder Misfire
Tracking down a performance problem caused by a bad or plugged-up injector isn't always easy —especially since three injectors are located under the upper intake plenum (1996–2000), and all six are located underneath it the 2001–2010 models.
To help you pinpoint the exact cause of a misfiring cylinder —whether it's an ignition issue, an engine mechanical fault, or a fuel injector that's not doing its job— I'm going to walk you through the method I use to get to the bottom of the problem.
Here's the core idea: every cylinder needs three things to fire —spark, fuel, and air.
If any one of those is missing, that cylinder goes "dead." The good news? It's usually just one —and with the right tests, you'll find the missing link fast.
Here's how I go about it:
- Start by figuring out which cylinder isn't firing:
- Once you've found the "dead" cylinder, you're halfway there.
- If your minivan is OBD II equipped (1996+), just scan for misfire codes —that'll usually tell you exactly which one's misfiring.
- If no codes show up or you have an OBD I minivan (with no misfire diagnostics), you can still ID the "dead" cylinder by doing a manual cylinder balance test.
- Check if that cylinder's getting spark:
- Now that you know which one's misfiring ("dead"), make sure its spark plug is actually firing.
- Start by testing the plug wire —make sure it's delivering spark to the plug.
- If there's no spark, then you're looking at an ignition system issue, not fuel —and now it's time to zero in on what part of the ignition system is failing.
- These other guides will walk you through the ignition system tests step by step:
- How To Test The Coil Pack (1990-1998 Chrysler 3.3L, 3.8L) (at: easyautodiagnostics.com).
- 1999-2001 Coil Pack Diagnostic Tests (Chrysler 3.3L) (at: easyautodiagnostics.com).
- Confirm that the misfiring cylinder has solid compression:
- Once you've ruled out a spark issue, your next move is to check compression on that "dead" cylinder.
- This step gets skipped way too often when diagnosing a misfire or a rough idle —but it's critical.
- The compression reading for that cylinder shouldn't be more than 15% lower than the highest reading from the other five. If it is, that cylinder won't fire correctly and will keep misfiring.
- You can follow this tutorial, it'll walk you through a compression test:
- Check the injector resistance:
- Once you've verified that the "dead" cylinder is getting spark and has good compression, it's injector testing time.
- Depending on which cylinder is "dead", you may or may not need to remove the intake manifold plenum to get to it.
- If the misfiring cylinder is on Bank 1 (cylinders 1, 3, or 5), you'll have to remove the upper intake plenum to access the injector —there's no way around it.
- Grab your multimeter and test the injector's resistance. It should fall within the correct range:
- Remove the intake manifold plenum for Noid light and injector spray test:
- With the plenum off, it's now possible to plug in a Noid light at the injector connector and make sure the PCM is sending it power and a pulse signal.
- This short guide covers how a Noid light is used:
- How To Use A Noid Light And Where To Buy It (at: easyautodiagnostics.com).
- Pull the injector and check the spray pattern:
- This is your next step —but only after you've confirmed the cylinder has spark, solid compression, and the injector's resistance is within spec.
- At this point, remove the injector and connect it to a fuel injector cleaner/tester tool (I'll show you where to get one).
- What you're looking for is a clean, even, cone-shaped spray coming from the nozzle.
The important thing to keep in mind when you're chasing down a misfire is that the key to success is ruling things out one step at a time —it's all about process of elimination.
The first thing to do is figure out which cylinder isn't firing —the one that's "dead". After that, your job is to confirm it's getting spark, compression, and fuel.
Working through the tests I outlined above, in that order, will help you quickly find what's missing —and zero in on the real issue without wasting time or money.
Vacuum Leaks Causing A Misfire Or Rough Idle
If your 3.3L V6 is idling rough —especially when cold— don't overlook a vacuum leak as the root cause. One of the most notorious troublemakers here is the lower intake manifold gasket, also known as the "valley pan" gasket.
When this gasket starts to fail, it can let in unmetered air right at the base of the intake —and the engine's gonna let you know. The first signs usually show up as a rough idle on a cold start —and just to be clear, "cold" doesn't mean winter weather.
I'm talking about when the engine hasn't been running for several hours, like first thing in the morning after it's been sitting overnight and is at ambient temperature.
You might also notice engine coolant leaking from the corners of the lower intake, with the passenger side being the most obvious spot.
That combination —coolant at the corners and rough idle when cold— is a big red flag that the valley pan gasket's on its way out.
If you suspect a vacuum leak but aren't 100% sure, go check out this guide where I show you exactly how to test for one using carb cleaner spray:
More 3.3L V6 Chrysler, Dodge, And Plymouth Minivan Tutorials
I've written several more tutorials for the V6 Chrysler, Dodge, and Plymouth minivans that you might find helpful. You can browse them all in this index:
If this info saved the day, buy me a beer!
