The spark plug is a small component of the ignition system, but one that plays an outsized role in keeping the engine running smoothly and optimally.
In this article I'm going to answer some of the most commonly asked questions about the spark plugs.
Contents of this tutorial at a glance:
APPLIES TO: This tutorial applies to the following vehicles:
- 3.1L V6 Buick Century: 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005.
- 3.1L V6 Buick Regal: 1994, 1995, 1996.
- 3.1L V6 Buick Skylark: 1994, 1995, 1996.
- 3.1L V6 Oldsmobile Achieva: 1994, 1995, 1996, 1997, 1998.
- 3.1L V6 Oldsmobile Cutlass: 1997, 1998, 1999.
- 3.1L V6 Oldsmobile Cutlass Ciera: 1994, 1995, 1996.
- 3.1L V6 Oldsmobile Cutlass Supreme: 1993, 1994, 1995, 1996, 1997.
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 does this by transmitting a spark from its center electrode to its side electrode (or vice versa).
Symptoms Of A Bad Spark Plug
The most common symptom of a bad spark plug is a misfire/rough idle condition.
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?
Quite a few different problems can cause the spark plug to stop sparking.
The following are the most common:
- 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?
Since a spark plug can cause a variety of problems, there's not just one thing that'll let you know that it's time to replace them.
Generally, spark plugs are replaced for the following reasons:
- 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?
When it comes to buying spark plugs, there is a huge selection of name brands and spark plug types to choose from.
My recommendation to you is to buy the original equipment spark plug that your vehicle came with from the factory.
This OE spark plug is the AC Delco brand of spark plugs. You can't go wrong buying the AC Delco brand of spark plugs for your vehicle.
Now having said that, any spark plug that is designed for your specific vehicle regardless of the name brand or the spark plug type, 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
If it's time to replace the spark plugs, keep the following important tips in mind:
TIP 1: Replace the spark plugs with a completely cold engine. The two cylinder heads of the 3.1L V6 engine are made of aluminum. This means that you've got to remove the spark plugs from a completely cold engine.
Why? Because you run the risk of damaging the spark plug hole threads if you remove the spark plugs from a hot engine.
Trust me, this is a nightmare that you want to avoid!
TIP 2: Check the air gap of the new spark plugs with a spark plug gapper. 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 3.1L V6 Buick, Oldsmobile Tutorials
You can find a complete list of 3.1L V6 Buick (Oldsmobile) tutorials in this index:
Here's a small sample of the tutorials you'll find in the index:
- How To Test Engine Compression Test (3.1L V6 Buick, Oldsmobile).
- How To Test A Blown Head Gasket (3.1L V6 Buick, Oldsmobile).
- How To Test The Fuel Pump (3.1L V6 Buick, Oldsmobile).
- How To Test The 24X Crankshaft Position Sensor (1995-1997 3.1L V6 Oldsmobile Cutlass Supreme).
If this info saved the day, buy me a beer!