What Do The Spark Plugs Do? (1988-1993 2.8L Chevrolet S10 Pickup, GMC S15 Pickup, GMC Sonoma)

The spark plugs are an important component of the ignition system and sooner or later, they'll need to be replaced.

In this article, I'll answer some of the most commonly asked questions about spark plugs.

APPLIES TO: This tutorial applies to the following vehicles:

• 2.8L Chevrolet S10 Pickup: 1988, 1989, 1990, 1991, 1992, 1993.
• 2.8L GMC S15 Pickup: 1988, 1989, 1990.
• 2.8L GMC Sonoma: 1991, 1992, 1993.

What Does A Spark Plug Do?

The spark plug is the component responsible for igniting the air-fuel mixture in the cylinder to which it's connected with a spark.

This spark is a high voltage spike that emanates from the ignition coil and travels through the distributor and spark plug wires to the spark plug.

Once this high voltage spike reaches the spark plug, it turns into a spark as it jumps from the spark plug's center electrode to its side electrode.

Symptoms Of A Bad Spark Plug

Spark plugs work under extreme conditions and eventually fail for one or more reasons, causing one of several engine performance problems.

The most common engine performance problem caused by a bad spark plug is an engine cylinder misfire.

You'll also see one or more of the following symptoms:

• Bad gas mileage.
• Extended engine cranking (engine takes longer than usual to start).
• A heavier-than-normal exhaust smell coming out of the tailpipe.
• The engine is not as peppy as it used to be.
• Hesitation when you accelerate the vehicle on the road.
• Fuel smell coming from the tailpipe.

What Causes A Spark Plug To Stop Working?

Quite a few things can cause the spark plug to fail:

• Normal wear and tear. In other words, they simply wear out.
• Carbon deposits blocking the air gap between the center and side electrodes.
• Damage caused by the installation process (for example, during a tune-up).

Carbon deposits blocking the spark plug's electrodes are usually caused by engine oil burning inside the cylinder the spark plug is connected to.

You can tell these engines apart because:

• Blue smoke comes out of the tailpipe (when the engine is running or when under load).
• You need to add engine oil to the engine on a regular basis.

How Do I Know My Spark Plugs Need Changing?

The time to replace the spark plugs varies from vehicle to vehicle. In general, spark plug replacement is warranted when one of the following conditions is met:

• You're following a recommended spark plug change interval.
• An engine performance issue has been attributed to a faulty spark plug.
• The spark plugs have been removed and are showing heavy wear and tear.

Which Spark Plugs Should I Buy?

The AC Delco brand of spark plugs are the factory original spark plugs used in your 2.8L V6 Chevrolet S10 pickup (GMC S15 pickup, GMC Sonoma).

The AC Delco brand of spark plugs are the spark plugs that I would recommend you install in your vehicle when it comes time to replace them.

Having said that, any other brand of spark plug specifically designed for your vehicle will work.

Should I Use 100,000 Mile Spark Plugs?

Spark plugs advertised as having a service life of up to 100,000 miles have platinum or iridium-tipped electrodes. Regular spark plugs with copper electrodes do not last that long.

Now the catch here is that if the engine is in perfect working condition (e.g. It's not burning oil) then these spark plugs will give you a service life of about 100,000 miles.

But if you have a high mileage engine that burns oil, you're not going to see anywhere near 100,000 miles on those spark plugs. Carbon buildup will eventually close the air gap between the spark plug electrodes and cause a misfire.

Important Tips And Suggestions

Here are a couple of important tips that will save you time (and frustration) when replacing the spark plugs:

TIP 1: Replace the spark plugs with a completely cold engine. The spark plug hole threads (in the cylinder head) can easily be stripped if the spark plugs are removed with a hot engine.

Stripping the spark plug hole threads in the cylinder head is a nightmare that can easily be avoided by removing the spark plugs when the engine is completely cold.

TIP 2: Check the air gap of the new spark plugs with a spark plug gapper. Don't trust that the spark plugs are already pre-gapped.

I've diagnosed quite a few misfire problems that were caused by spark plugs that were advertised as being pre-gapped but were not.

NOTE: If you're using multi-electrode spark plugs, like the Bosch Platinum+4 spark plugs (which have four side electrodes), then you don't need to check the air gap.

TIP 3: Use a torque wrench to tighten the spark plugs. If you don't tighten the spark plugs enough you run the risk of having them come out as you're driving down the road. This could also damage the spark plug hole threads in the cylinder heads.

If you over tighten the spark plugs, then you run the risk of damaging the threads of the spark plug hole.

The way to avoid any of these problems is to use a torque wrench to tighten the spark plugs. Now, it's easier said than done because some of the spark plugs are in very tight places and it can be challenging to use a torque wrench on them. Still, you won't go wrong if you use a torque wrench.