Common Causes Of Spark Plug Failure (1990-2000 3.0L V6 Dodge And Plymouth Minivan)

Spark plugs are such a small ignition system component, but they play a huge role in keeping your minivan's engine running smoothly.

When they wear out or fail, misfires, rough idling, and poor performance are sure to follow.

In this guide, I'll walk you through the most common reasons spark plugs go bad and when they should be replaced.

Whether you're dealing with worn-out plugs or ones fouled by oil and carbon, you'll know exactly what to look for and what to do next.

APPLIES TO: This tutorial applies to the following vehicles:

• 3.0L V6 Dodge Caravan: 1990, 1991, 1992, 1993, 1996, 1997, 1998, 1999, 2000.
• 3.0L V6 Dodge Grand Caravan: 1990, 1991, 1992, 1993, 1996, 1997, 1998, 1999, 2000.
• 3.0L V6 Plymouth Voyager: 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000.
• 3.0L V6 Plymouth Grand Voyager: 1990, 1991, 1992, 1993, 81994, 1995, 1996, 1997, 1998, 1999, 2000.

What Causes Spark Plugs To Wear Out?

Spark plugs take a beating every time the engine fires. With each ignition event, a spark jumps from the center electrode to the side electrode —and over time, that consistent arcing wears down even the toughest materials.

Now, normal wear and tear doesn't kill a spark plug overnight. But after tens of thousands of miles, it adds up and eventually causes the spark plug to fail.

If your minivan came with original equipment copper spark plugs, you can expect them to last about 50,000 to 60,000 miles before they wear out.

If it's equipped with platinum-tipped spark plugs, they usually last twice the distance —around 100,000 miles of service before needing replacement.

But here's the thing —on high mileage engines, most spark plugs don't fail because of age or mileage alone. The #1 cause of premature spark plug failure is carbon buildup.

This buildup happens as the engine starts to age and starts burning oil. That oil gets into the combustion chamber and leaves carbon deposits behind, especially around the electrodes.

Once that carbon clogs up the gap between the electrodes, the spark can't jump across like it's supposed to. The result? You get a dead cylinder, which leads to engine misfires and rough idle.

If you're driving a 1996+ minivan with OBD II, a clogged or fouled spark plug will usually trigger the check engine light and set a misfire code —like P0301 through P0306, depending on which cylinder is misfiring.

When Should I Replace The Spark Plugs?

The best time to replace your spark plugs really depends on one of two things:

1. Following the recommended spark plug change interval set out in the owner's manual.
2. The condition of your engine —especially whether or not it's burning oil.

That owner's manual recommendation is based on ideal conditions —meaning the engine's running clean, not burning oil, and the right type of spark plugs are installed (copper plugs or platinum or iridium types). So if your engine's in good shape, that schedule is a solid guide.

If your engine is burning oil, carbon deposits can build up quickly and foul the spark plugs long before they're actually worn out. In fact, you might end up changing them every few months just to keep the engine running smoothly.

You'll know it's time to replace the spark plugs in an oil-burning engine when:

• The engine starts idling roughly when you come to a stop,
• or the check engine light pops on with a misfire trouble code.

Wondering if your engine is burning oil? Here are a few telltale signs:

• You have to add oil every week just to keep it topped off.
• You see blue smoke from the tailpipe when accelerating.
• You see blue smoke when first starting the engine —especially after it's been sitting for a while.

Now, if your engine isn't burning oil, great news —you'll likely get the full service life out of your spark plugs without any surprises.

For minivans equipped with copper spark plugs (OEM), you should plan to replace them at around 50,000 miles.

If your minivan uses platinum or iridium tipped spark plugs, they generally last longer —you're looking at a typical service life of about 100,000 miles before they need to be replaced.

Which Spark Plugs Should I Buy: Champion Or Brand X?

The original factory spark plugs for the 3.0L V6 Dodge Caravan or Grand Caravan (or Plymouth Voyager or Grand Voyager) are Champion brand copper spark plugs.

Since Champion spark plugs are what came installed from the factory, it's a solid option when it's time to replace them.

That said, you don't have to use Champion. Any spark plug brand that's a proper match for your 3.0L V6 minivan will do the job just fine.

Now here's the important part:

• If your engine is burning oil, don't waste money on expensive spark plugs. Go with the cheapest copper plugs you can find —even if they're a different brand. Oil-fouling will likely cause misfires and ruin them anyway, no matter the brand or price.
• If your engine is NOT burning oil, then you can go with platinum tipped spark plugs for better longevity and performance. Brand X platinum plugs will work just fine —you don't need to stick with Champion in that case.

Other Causes Of Spark Plug Failure

If a spark plug stops firing, the result is a misfire —plain and simple. And if your minivan is OBD II equipped, you'll usually see the check engine light come on along with a misfire trouble code like P0300 through P0306.

There are two main categories of problems that can cause a spark plug to stop sparking properly:

1. Mechanical or engine-related issues that foul the spark plug with oil, unburned fuel, or carbon buildup.

Some common causes include:

• Excessive oil burning in one or more cylinders due to worn piston rings or leaking valve stem seals.
• A faulty fuel injector flooding the cylinder and soaking the plug with raw fuel.
• A spark plug wire that's no longer delivering spark —either due to age, damage, or poor connection.
• A bad distributor cap with one or more towers that aren't transmitting spark anymore.
• Low compression in a specific cylinder, which leads to incomplete combustion and plug fouling.

2. Mistakes during spark plug installation that damage the plug or prevent it from working right.

Examples of installer error include:

• Over-tightening the spark plug and cracking the ceramic insulator.
• Dropping the plug before installation and unknowingly damaging it.
• Accidentally closing the spark gap while handling the plug.
• Installing the spark plug with the wrong gap setting for your engine.
• Washing the engine while it's hot, causing thermal shock and cracking the porcelain insulator.

CASE STUDIES:

I've diagnosed and resolved quite a few cylinder misfires caused by installation errors (it happens), here's one case study I wrote about a few years back ago on this subject:

• Diagnosing A Toyota Corolla Misfire Case Study.

The following case study involved my brother-in-law's vehicle, which had a cylinder with low compression causing a cylinder misfire:

• Troubleshooting A Hard To Diagnose Misfire Case Study (GM 3.1L, 3.4L).

In this last case study, the spark plug and spark plug wire had carbon tracks causing a cylinder misfire:

• Carbon Tracks Are A Common Cause Of Ignition Misfires (at: easyautodiagnostics.com).

More 3.0L V6 Dodge And Plymouth Minivan Tutorials

You can find a complete list of tutorials in this index:

• 3.0L V6 Dodge And Plymouth Minivan Index Of Articles.

Here's a sample of the tutorials you'll find in the index:

• How To Test For A Blown Head Gasket (1991-2000 3.0L Caravan, Grand Caravan, Voyager, Grand Voyager).
• How To Test For A Broken Timing Belt (1988-2000 3.0L SOHC Chrysler).
• How To Replace The Distributor (1988-2000 3.0L V6 Chrysler, Dodge, Plymouth).
• How To Test Engine Compression (1987-2000 3.0L V6 Chrysler, Dodge, Plymouth).