What Do The Spark Plugs Do? (3.4L V6 Chevrolet, Pontiac)

The spark plug is such a small component of the ignition system, but it plays a very important role in starting and keeping the engine running.

In this tutorial, I'm going to answer some of the most commonly asked questions about the spark plugs.

You can find this tutorial in Spanish here: La Bujía ¿Qué Es Y Para Qué Sirve? (1996-2005 3.4L V6 Chevrolet, Pontiac) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to the following vehicles:

• 3.4L V6 Chevrolet Impala: 2000, 2001, 2002, 2003, 2004, 2005.
• 3.4L V6 Chevrolet Monte Carlo: 2000, 2001, 2002, 2003, 2004, 2005.
• 3.4L V6 Chevrolet Lumina Minivan: 1996.
• 3.4L V6 Chevrolet Venture: 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005.
• 3.4L V6 Pontiac Aztek: 2001, 2002, 2003, 2004, 2005.
• 3.4L V6 Pontiac Grand Am: 1999, 2000, 2001, 2002, 2003, 2004, 2005.
• 3.4L V6 Pontiac Montana: 1999, 2000, 2001, 2002, 2003, 2004, 2005.
• 3.4L V6 Pontiac Trans Sport: 1996, 1997, 1998.

What Does A Spark Plug Do?

The spark plug has the job of igniting the air/fuel mixture inside the cylinder that it's connected to.

It accomplishes this by transmitting a spark from its center electrode to its side electrode.

As you're probably already aware, this is the spark that the ignition coil pack creates and delivers to the spark plug via a spark plug wire (high-tension wire).

Symptoms Of A Bad Spark Plug

Generally, a bad spark plug will cause a misfire problem or a rough idle condition.

Since all of the 3.4L V6 equipped vehicles are equipped with OBD II, you're going to see one or more of the following diagnostic trouble codes (when one or more spark plugs fail):

• P0300: Random Cylinder Misfire.
• P0301: Cylinder #1 Misfire.
• P0302: Cylinder #2 Misfire.
• P0303: Cylinder #3 Misfire.
• P0304: Cylinder #4 Misfire.
• P0305: Cylinder #5 Misfire.
• P0306: Cylinder #6 Misfire.

Besides a misfire trouble code illuminating the check engine light, you'll 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.

What Causes A Spark Plug To Stop Working?

Quite a few factors can cause a spark plug to stop sparking. The most common are:

• 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 (like for example during a tune-up).

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

You can tell these engines apart because:

• They have blue smoke coming out of the tailpipe (when the engine is running or when under load).
• They need to have engine oil added on a regular basis.

How Do I Know My Spark Plugs Need Changing?

Spark plugs are replaced for a number of reasons. The most common are:

• They've been removed and are showing signs of heavy wear and tear.
• They're causing an engine performance problem.
• You are following a recommended spark plug change interval.

Which Spark Plugs Should I Buy?

Your vehicle came equipped with AC Delco spark plugs when it left the factory.

This means that the AC Delco brand of spark plugs are the original equipment (OE) spark plugs for your Chevrolet (Pontiac).

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.

Now having said that, any other brand of spark plug that is specifically designed for your specific vehicle will work.

Should I Use 100,000 Mile Spark Plugs?

Spark plugs that are advertised as having a service life up to 100,000 miles have platinum or iridium tipped electrodes. Regular spark plugs, which have 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 got a high mileage engine that is burning 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 cylinder heads of your 3.4L V6 engine are made of aluminum, and this means that the spark plug hole threads 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 with a completely cold engine.

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.

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.

More 3.4L V6 Chevrolet, Pontiac Tutorials

You can find a complete list of 3.4L V6 Chevrolet (Pontiac) tutorials in this index:

• GM 3.4L Index Of Articles.

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

• How To Test Engine Compression Test (3.4L V6 Chevrolet, Pontiac).
• How To Test A Blown Head Gasket (3.4L V6 Chevrolet, Pontiac).
• What Does The CKP Sensor Do? (3.4L V6 Chevrolet, Pontiac).
• What Does The Throttle Position Sensor Do? (3.4L V6 Chevrolet, Pontiac).