Common Causes Of Spark Plug Failure (1997-2003 2.0L Ford Escort, Mercury Tracer)

  • By: Abraham Torres-Arredondo
  • Created: 10 September 2025
  • Updated: 10 September 2025
  • Articl Id: 3
Common Causes Of Spark Plug Failure (1997, 1998, 1999, 2000, 2001, 2002, 2003 2.0L Ford Escort, Mercury Tracer)

Spark plugs may be small in size, but man, do they do a lot of the heavy lifting when it comes to keeping your Ford Escort or Mercury Tracer running the way it should.

Once one or all of the spark plugs wear out or fail, you'll notice engine performance issues like cylinder misfires, rough idle, and loss of performance across the board.

In this guide, I'll explain the main reasons spark plugs end up failing and give you some pointers on when it's time to replace them.

Contents of this tutorial:

APPLIES TO: This tutorial applies to the following vehicles:

  • 2.0L SOHC (P) Ford Escort: 1997, 1998, 1999, 2000, 2001, 2002.
  • 2.0L DOHC (3) Ford Escort ZX-2: 1997, 1998, 1999, 2000, 2001, 2002.
  • 2.0L SOHC Mercury Tracer: 1997, 1998, 1999.

What Causes Spark Plugs To Wear Out?

Every time you crank and start the engine, those spark plugs take a beating. With each ignition event, you've got a spark jumping from the center electrode over to the side electrode —and that nonstop arcing wears down even the toughest metal bit by bit.

That kind of wear doesn't kill a spark plug right away, but after you've been racking up tens of thousands of miles, the erosion adds up and eventually leads to worn and failing spark plugs.

If you're using original equipment copper plugs in your Escort or Tracer, you can usually count on about 50,000 to 60,000 miles of service before they wear down to nubs.

If your vehicle has platinum-tipped spark plugs installed, you'll get about double that distance —close to 100,000 miles before, you're needing to replace them.

But here's the thing —on a high-mileage engine, spark plugs usually don't just fail from age or miles. The #1 culprit behind premature spark plug failure is carbon buildup.

This buildup happens as the engine ages and starts burning engine oil. That oil sneaks into the combustion chamber and leaves heavy carbon deposits behind, especially on and around the spark plug electrodes.

Once carbon clogs up the gap between the electrodes, the spark isn't able to jump across the way it should. The end result? You'll have a dead cylinder causing a cylinder misfire and a rough idle.

When a spark plug fouls like this, you'll see the check engine light come on and have a misfire code —like P0300 through P0304, depending on which cylinder is giving you trouble.

When Should I Replace The Spark Plugs?

Figuring out the best time to change the spark plugs really comes down to two main things:

  1. Following the spark plug replacement interval listed in your owner's manual.
  2. The actual condition of your Escort or Tracer's engine —especially if it's burning engine oil.

The mileage schedule in the owner's manual is written with "perfect world" conditions in mind. That means the engine is running in tip-top shape, not burning oil, and has the correct spark plugs (copper, platinum, or iridium) installed. If your engine is healthy, that schedule is a solid guide you can go by.

Now, once your Escort or Tracer's engine starts burning oil, carbon deposits build up on the spark plugs a lot sooner than normal (even before they physically wear out). In that case, you may find yourself changing spark plugs every few months to keep it running smooth.

If the engine burns oil, you'll know the spark plugs are carbon-fouled and need replacement when you notice:

  • The engine idles rough (like when you're waiting at a traffic light),
  • Or the check engine light comes on with a misfire code stored in memory.

If you're wondering whether your Escort or Tracer's engine is burning oil, here are some dead giveaways:

  • You're having to add engine oil every week to keep it at the full mark (on the dipstick).
  • You're seeing blue smoke coming out of the tailpipe (especially when accelerating).
  • You're noticing blue smoke right after starting the engine —especially after it's been sitting for a while.

On the other hand, if your engine isn't burning oil, that's the good news. You're probably getting the full service life out of your plugs without any early surprises.

For engines running on copper spark plugs (OEM type), you should plan on changing them at about 50,000 miles.

If your Escort or Tracer is equipped with platinum or iridium-tipped plugs, they're usually lasting much longer —you're looking at close to 100,000 miles of service before you need to swap them out.

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

From the factory, your 2.0L Ford Escort (Mercury Tracer) rolled off the line with Motorcraft copper spark plugs installed.

Because Motorcraft plugs are the original equipment (OE), you can always stick with them when it's time for a tune-up —knowing they're a solid choice.

That being said, you're not locked into Motorcraft only. As long as the spark plugs are the correct match for your 2.0L Ford Escort or Mercury Tracer, any quality brand will do just fine.

Here's the part you should pay attention to:

  • If the engine is burning oil, it's not worth dropping cash on pricey spark plugs. You're better off installing the cheapest copper plugs you can pick up —brand doesn't matter. Once carbon starts fouling them, you'll be dealing with misfires no matter what name is on the box.
  • If the engine isn't burning oil, then you can step up to platinum-tipped spark plugs for longer service life and better performance. Any good brand of platinum spark plug will serve you well —you don't have to stick with Motorcraft unless you want to.

Other Causes Of Spark Plug Failure

As I've mentioned before, when a spark plug stops firing, you'll have a cylinder misfire on your hands —plain and simple. Most of the time, you'll also see the check engine light come on with a stored misfire code (P0300 thru P0306).

We can group the reasons why a spark plug stops sparking into two main categories:

1. Engine mechanical problems that foul the spark plug with engine oil, raw fuel, or carbon deposits.

Here are some of the things to look for:

  • The engine is burning oil in one or more cylinders because the piston rings are worn or the valve stem seals are leaking.
  • A fuel injector is sticking open and flooding the cylinder, leaving the plug soaked in gasoline.
  • A spark plug wire has failed and isn't delivering spark to its spark plug —whether it's from age, physical damage, or a poor connection.
  • The ignition coil has failed and one of its towers isn't sending spark to its spark plug.
  • One or more cylinders are running with low compression, which causes incomplete combustion and fouled plugs.

2. Installation mistakes that damaged the spark plug or keep it from firing the way it's supposed to.

Some common ways this happens include:

  • The spark plug was over-tightened and its ceramic insulator cracked.
  • The spark plug got dropped before being installed and ended up with a cracked ceramic insulator.
  • The spark plug air gap accidentally got closed up while handling the plug.
  • The spark plug was installed with the wrong air gap setting.
  • The engine was washed while still hot, and the sudden temperature change cracked the spark plug's 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:

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

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

More 2.0L Ford Escort And Mercury Tracer Diagnostic Tutorials

You can find a complete list of 2.0L Ford Escort and Mercury Tracer tutorials in this index:

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

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