Original Equipment Spark Plugs

[jorton]

Since I own a Chrysler product I have been trying to figure out why some Chrysler models have standard/copper spark plugs as OE from the factory. I could understand my Jeep Patriot came with standard/copper plugs because it's a cheap car. But Dodge Ram Hemi uses the same style standard/copper plug. That is not a cheap car. Ram owners should not have to change plugs every 30,000 - 40,000 miles.

My co-worker owned a Suzuki SX4 that came with OE Irdium spark plugs. This is also a cheap car. He changed them @ 180,000 miles. Spark plug gap was still within spec.

Here is the best info I've found on Irdium Spark plugs:

"WILL AN IRIDIUM SPARK PLUG BE BENEFICIAL FOR MY PARTICULAR ENGINE?

This is very subjective. The vast majority of vehicles/engines will benefit from replacing a standard spark plug with an Iridium spark plug.

Most benefit will result if:

There is a very close Iridium spark plug match for your standard spark plug (i.e. overall design is very similar)

The standard spark plug you are replacing is a basic copper plug (the Iridium plug will then be a more significant upgrade)

The engine has a large cylinder capacity and a large number of cylinders

Least benefit will be realized if:

There is no close match for your standard spark plug, it isn't worth compromising plug design purely to use an Iridium plug type.

The standard plugs are already a performance or enhanced design. Some standard (Original Equipment) plugs are Iridium or fine wire platinum types, these may already provide the ultimate performance and service life for your particular engine. Fitting an aftermarket Iridium plug may actually result in a drop in performance and service life."
from: http://www.sparkplugs.co.uk/iridium-spark-plugs

Do you think Chrysler uses standard/copper spark plugs in new vehicles just to save money? And to make dealers service departments more money?

Well, you know, they can do that if they want to. Chrysler has had some very nice looking models to compliment cheap models like Patriot, Compass and Caliber.

 

[Ethan1]

Exotic plugs are not a panacea, that's why.

 

[BrocLuno]

Some ignition systems (like the one in my SAAB) use the plug corona gap resistance to set anti-detonation timing (mostly under boost). If you change the plug type, or the plug gap, it will run different. Maybe better/maybe worse.

you really need to spend time with your car model on some forums of like vehicles and see what others are finding out ...

That said, there are lot of old wife's tales about ignitions. Like a HEI can't rev past 5,000, or a Dura-Spark can't jump 0.060" - or you can't rev a Mopar w/o a Purple Box, etc.

It's all [censored] if you do the research and make appropriate upgrades and choices in parts

General wiring and Engine to ECU ground path is the number one failure of all these systems, especially as they age ... Remember, there is a voltage potential to move current around the system until it gets used up. Then it has to get back to the source with ZERO voltage and the same current load.

The number one improvement you can make is to run a big'ish premium fine stranded wire with crimped and soldered lugs from the engine to the firewall near the ECU. Use tinned marine grade cable and HD lugs. Clean the bolt surfaces. Use some grease on the threads to prevent corrosion in the future. Your engine will run better longer

 

[jorton]

Originally Posted By: BrocLuno


The number one improvement you can make is to run a big'ish premium fine stranded wire with crimped and soldered lugs from the engine to the firewall near the ECU. Use tinned marine grade cable and HD lugs. Clean the bolt surfaces. Use some grease on the threads to prevent corrosion in the future. Your engine will run better longer

Thanks! That'll my next project on my 05 Focus.

 

[asand1]

The ONLY advantage of iridium plugs is long life. Copper conducts better and is commonly believed to perform better. Some also believe replacing plugs more often will reduce the chances of plugs seizing and pulling the threads out of the head.

Iridium plugs are often used in engine/compartments that require much intensive labor to replace the plugs. A hemi should be very easy to replace the plugs and personally I would not want iridium plugs in one.

More expensive does not equal better, just ask Audi owners.

 

[SteveSRT8]

Yet the 5.7 and the 6.1, which have IDENTICAL ignition systems, ship with "coppers" and iridiums respectively. They are ridiculously easy to replace as a DIY.

Are you proposing that an SRT8 owner with iridiums should replace them with "coppers"? I quote that because all plugs have significant copper inside them and no car uses copper firing tips or any part involved inside the combustion chamber.

If there were any misfiring with any plug you can bet the OEM's would change them immediately. The main reason the 5.7 ships with "coppers" is cost, pure and simple. I'm sure the stealerships love hooking Hemi owners for big bucks to change out cheap plugs, too.

With a late model Hemi you can pick your plug by how often you wish to fool with them. Like to tinker?

 

[Y_K]

"Copper conducts better" is another thing people repeat without thinking.
yes, it is better, when you deal with kilometers of a conductor as opposed to millimeters. Geometry and Hot vs Cold is far more important

 

[nthach]

The firing end of a spark plug isn't copper - "regular" plugs use nickel alloys. And there are several different types of platinum/iridium plugs as well.

 

[AntsinmyEyes]

Since there is 16 plugs in the hemi i used iridiums in mine (didnt want to have to do the job again). Also switched to ngk as i believe them to he a better plug than champions, something that chrysler has also done in later model years. Have noticed no reduction in performance or misfires like everyone says you will get when you wlswitch from oem plugs.

The 2 that are under the brake booster are a [censored] but otherwise it a straightforward job. I wouldnt say that it was an easy car to change plugs in though.