What Do The Spark Plugs Do? (3.4L V6 Buick, Oldsmobile)

The spark plug is not much to look at, but oh boy does it have a big job to do! Your 3.4L V6 engine comes equipped with six of them.

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

APPLIES TO: This tutorial applies to the following vehicles:

• 3.4L V6 Buick Rendezvous: 2002, 2003, 2004, 2005.
• 3.4L V6 Oldsmobile Alero: 1999, 2000, 2001, 2002, 2003, 2004.
• 3.4L V6 Oldsmobile Silhouette: 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004.

What Does A Spark Plug Do?

In a nutshell, the job of the spark plug is to transmit the spark that the ignition coil pack creates into the cylinder it is attached to.

This spark is delivered from the ignition coil pack to the spark plug by an ignition high-tension wire (commonly known as a spark plug wire).

Symptoms Of A Bad Spark Plug

Here's a basic list of the symptoms you'll see when a spark plug stops functioning:

• Rough idle.
• 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.
• Misfire trouble codes lighting up the check engine light:
  • 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.

What Causes A Spark Plug To Stop Working?

There are a couple of things/conditions that can cause a spark plug to stop transmitting spark. These 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?

There are quite a few factors that will have you changing the spark plugs.

The three 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?

If you have to replace the spark plugs, you should replace them with the factory original spark plugs. On all GM vehicles, the original equipment spark plug is the AC Delco brand of spark plugs.

Of course, it's important to note that any spark plug that is made for your specific vehicle will work (even if it's not the OE brand).

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

If you're about to replace the spark plugs, keep in mind the following important tips and suggestions:

TIP 1: Replace the spark plugs with a completely cold engine. This is a very important suggestion because you run the risk of damaging the spark plug hole threads by replacing them with a hot engine.

Stripping a spark plug hole thread is a nightmare that you can easily avoid by removing the spark plugs with a cold engine.

TIP 2: Check the air gap of the new spark plugs with a spark plug gapper. I strongly recommend that you double check that the spark plug gap is correctly set to your vehicle's recommended specification when installing spark plugs.

Don't trust that they are gapped! I've solved more than one driveability problem that was due to incorrectly gapped spark plugs.

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 Buick, Oldsmobile Tutorials

You can find a complete list of 3.4L V6 Buick (Oldsmobile) 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 Buick, Oldsmobile).
• How To Test A Blown Head Gasket (3.4L V6 Buick, Oldsmobile).
• What Does The CKP Sensor Do? (3.4L V6 Buick, Oldsmobile).
• How To Test The Throttle Position Sensor (3.4L V6 Buick, Oldsmobile).