Spark plug confusion

[kennyz]

The original plugs in my 2000 SSEi were AC 41-921 which I am told is a double platinum plug. I have also read that I shouldn`t use platinum plugs. So I shouldn`t replace my plugs with what came in the car originally??
What is the general consensus for what I should use as a replacement. I usually try to stay with OEM.

[haro1225]

Is that what you took out? Someone could have put those in there, the OE plug should be iridium. AC delco number 41-101.

[96 SSEi]

yes, when I wnt to GM, they list a platinum plug but all here stay with iridium or copper

[kennyz]

Is that what you took out? Someone could have put those in there, the OE plug should be iridium. AC delco number 41-101.

Yep, that`s what came out, even has a factory part number.
So you recommend replacing with the 41-101??

[nos4blood70]

Get iridium plugs, nothing else. Copper doesn't last and platinum will cause issues.

[00Beast]

Just because someone used an AC Delco plug at one point doesn't mean it was OEM. OEM plugs should have been the 41-101 or it's iridium predecessor.

[MKMike]

I have replaced my plugs with ACDelco 41-101 spark plugs, based upon the experiences of numerous members of this and other forums.

What they have happen was pre-ignition when using platinum plugs.
Pre-ignition can do serious engine damage, so it is far wiser to use either copper or iridium plugs instead.
ACDelco's website lists 41-101 as the iridium plug to use, so you can rest assured it is a proper replacement plug.

Although I drive much more like a little old lady than a racecar driver, I'd rather spend a couple of extra bucks and avoid any potential problems.

Just because someone used an AC Delco plug at one point doesn't mean it was OEM. OEM plugs should have been the 41-101 or it's iridium predecessor.

That "someone" was probably GM.
According to GM's manuals, the OE plug was not iridium.

The 2000 Bonneville owner's manual, page 6-70 states that the original spark plug was NGK Type PTR4B-15:

Spark Plugs . . . . . . . . . . . . . . . . . AC Type 41-921*
Gap: 0.060 inch (1.52 mm)
*On 3800 V6 Supercharged Engine (Code 1) only, this
replaces original spark plug NGK Type PTR4B-15.

View the original manual here https://my.gm.com/content/dam/gmownerce ... owners.pdf

My 2001 SSEI still had original platinum NGKs, (marked NGK PTR4B-15 12565030) when I bought it a couple of months ago
It also had what I surmise was the original fuel filter.
Ever see black gasoline?
I have
That's how filthy the filter was.


Even the 2002 owner's and service manuals list only 41-921 plugs for both NA and supercharged models BUT , as stated earlier it is advisable to use the 41-101 iridium plugs instead.

[CMNTMXR57]

I think an engine 101 course is needed. Pre-ignition IS NOT caused by the choice of metal used in the tip of a spark plug. The ignition coil in this car, as well as most modern electronic controlled spark systems, has WELL MORE than enough power to fire ANY metal @ .060" gap. That thing could fire a plug with a 10ft gap. Ok, that was a little sarcasm. But it's gonna easily fire platinum, iridium, titanium, plutonium, etc...

Pre-ignition is the ignition of the air fuel mixture, in the combustion chamber, BEFORE the spark plug fires. Seriously folks, it's right in the name... "PRE-IGNITION"

Now one "could" argue that a hot electrode on a plug could cause pre-ignition. But again, a coil that makes 30,000 - 40,000 volts of electricity (what the average automotive ignition coil makes, not 3800 specific), is gonna fire and get hot, the electrode of any plug, be it Platinum, Iridium, Titanium, Plutonium. So it's really an irrelevant issue at that point!

The choice of metal used in a spark plug is purely for longevity purposes. The harder the metal, the longer it lasts. If your goal is maximum maintenance and not having to change plugs on your car during the lifetime you own it. Go as hard a metal as possible. The downside to that is, the harder the metal, the more electrical resistance it has, meaning the coil does have to work harder to fire it. On the flip side, if you want the strongest spark possible, you want a softer more conductive, lesser resistance metal... I.E. copper is a good choice. I run coppers in the GTO. But I change them annually (typically) with only a couple hundred miles on them...

It's all in the goals.

To summarize, if your car CAME from the factory with Platinum, and the manual calls for Platinum, you will be fine going with Platinum. If you want to do one better, and you're restless at night because you're worried about some form of inobservable pre-ignition symptom (which the only way you would even know is via a live scan of the PCM and looking for knock retard), as the PCM will dial back and adjust before you even know it, you can go iridium.

You, sitting in the driver seat, ISN'T going to detect any pre-ignition. And if you are, it's fairly large and something else, NOT what metal is in the tips of the electrodes of your spark plugs.

[MKMike]

I think an engine 101 course is needed. Pre-ignition IS NOT caused by the choice of metal used in the tip of a spark plug. The ignition coil in this car, as well as most modern electronic controlled spark systems, has WELL MORE than enough power to fire ANY metal @ .060" gap. That thing could fire a plug with a 10ft gap. Ok, that was a little sarcasm. But it's gonna easily fire platinum, iridium, titanium, plutonium, etc...
The choice of metal used in a spark plug is purely for longevity purposes.

Maybe you're right and maybe not....

If these articles are to be believed, then your comments are seemingly not accurate.

http://www.carid.com/articles/types-of-spark-plugs.html states that ," Because platinum is a less conductive material, it doesn’t deliver the effective power transfer of copper and may become overheated easier under performance driving conditions. "

Supercharged engine boost would seemingly fall into the "performance driving conditions" category.

Lets face it, the sole reason you're expected to use premium gasoline in the supercharged Bonnies is to prevent pre-ignition, which supercharged engines are more susceptible to.

As for being "undetectable" IDK...
"A pinging noise on acceleration is a symptom of pre-ignition. Left untreated pre-ignition can severely damage an engine. The excessive pressure developed can damage pistons and cause head gasket failure. Many things cause pre-ignition and correction always depends on finding and correcting the cause(s)."
and this " The tip of a spark plug can become hot enough to ignite the fuel/air mixture prematurely."
are quoted from here
http://www.agcoauto.com/content/news/p2_articleid/60

I based my comments on reports by other L67 users AND after reading articles such as this one, which states ,"Pre-ignition caused by some other ignition source such as an overheated spark plug tip, carbon deposits in the combustion chamber and, rarely, a burned exhaust valve; all act as a glow plug to ignite the charge."
http://www.contactmagazine.com/Issue54/ ... asics.html



Last of all is a simple assessment of the practical differences between the 3 types of plugs:
http://www.carsdirect.com/car-repair/co ... erformance
asserts that, "Platinum and Iridium plugs perform at a lower level than copper spark plugs, because they are less conductive and they tend to overheat. However, the overall longevity of these two types of metal is better than copper plugs. In reality, copper has the best performance of all three and the worst longevity. Platinum has good longevity and the worst performance. Iridium has good longevity and a performance that is decent, which is why iridium plugs tend to be more expensive than any other type. Still, the difference between these plugs in terms of overall quality is minimal, as there is a trade off for each."

Are the differences in real world use significant enough to warrant avoiding platinum plugs in our aging supercharged engines?
Maybe the platinums were fine for a new engine, but as the engine deposits build up over the years and miles, copper and iridium are the safer choices.

Who knows?
What I do know about GM's build of these cars is that they chose to use cheap plastic lower intake gaskets which regularly fail despite their "special" Dex-cool antifreeze, on the often ridiculously leaky Bonnevilles.

Should I put my trust in the fact that they know best when it comes to the plugs?
If they knew it all from research, there would seldom be any recalls or TSBs issued.

What I can tell you with certainty is that I am too lazy to change the plugs annually and would rather not concern myself with the possible need for kicking myself if the engine was damaged because I spent 2 dollars less per plug

[AJT2004]

The reason pre-ignition would not be detectable (to the driver's ears) is due to the knock sensor(s) which will ultimately signal to retard the timing eliminating the pinging or knock. That is why (in theory) performance and MPG drop when you use regular fuel in an engine that is tuned for premium fuel. Interesting article(s) this was also quoted;

"A second system for reducing pre-ignition is the knock sensor(s). The knock sensor informs the computer that when knocking, such as pinging or valve clatter occurs. The computer modifies ignition and in some cases valve timing, to lower cylinder temperature. This helps the fuel/air mixture to ignite later, compared with piston position"

[MKMike]

The reason pre-ignition would not be detectable (to the driver's ears) is due to the knock sensor(s) which will ultimately signal to retard the timing eliminating the pinging or knock. That is why (in theory) performance and MPG drop when you use regular fuel in an engine that is tuned for premium fuel. Interesting article(s) this was also quoted;

"A second system for reducing pre-ignition is the knock sensor(s). The knock sensor informs the computer that when knocking, such as pinging or valve clatter occurs. The computer modifies ignition and in some cases valve timing, to lower cylinder temperature. This helps the fuel/air mixture to ignite later, compared with piston position"

Makes sense.

[CMNTMXR57]

No, my statements are not inaccurate.

Platinum is a harder metal than copper. Iridium is a harder metal than Platinum (both harder and stronger than Platinum). The harder the metal, the higher the resistance for the metal, the higher resistance, the more power from that coil is needed to fire that plug at that gap.

For a S/C engine (or any forced induction engine essentially), especially as you increase boost, it is sometimes recommended that you reduce the gap to avoid potential flame kernel blowout. Meaning OEM boost, on an OEM intake, on an OEM pulley, etc, etc. .060 is fine. However once you start modifying, adding boost, adding air intake volume, etc. this needs to change. Change perhaps to a colder range plug if neccessary, as well as a smaller gap.

THIS is where people may be getting what they're calling "pre-ignition". Running a colder heat range plug and/or running a too large gap for the amount of boost, which translates into higher cylinder pressure, causing potential blowout, leading to a stumble and/or misfire.

As I also mentioned, and then AJ reiterated, any "pre-ignition" is picked up by the Knock sensors, and knock retard dials back timing. Some level of KR can be acceptable at WOT. This is a whole different conversation though.

Your comment about GM's LIM/UIM issue and not being able to trust them with spark plugs on your engine is unfounded. GM has a lot of highly intelligent individuals that are engineers that create this stuff and they do a lot right. At least they get a lot more right than their failures otherwise they'd be out of business. And truth be told, I'm going to trust them first with what they tell me to put in the product THEY designed.

With that said, GM lists this for 2000 Bonneville's (and I know it's repeat information);
VIN K (RPO L36): Plug AC Delco 41-921 (a Platinum Plug), gapped @ .060
VIN 1 (RPO L67): Plug NGK PTR4B-15 (a Platinum Plug), gapped at .060

However, GM also addresses the use of either Platinum or Iridium plugs in their engines;

#PIP3069C: Information - Iridium and Platinum Tip Spark Plug Maintenance - keywords 30K major minor preventative removal remove replacement tune up - (Apr 4, 2006)


Subject: Information - Iridium and Platinum Tip Spark Plug Maintenance


Models: All GM Passenger Cars and Trucks

with Iridium or Platinum Tipped Spark Plugs




--------------------------------------------------------------------------------

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
The information below was originally sent to all GM Dealers on October 14, 1999 as a DCS message. This information applies to all vehicles equipped with Iridium or Platinum Tipped Spark Plugs.

Recommendation/Instructions:
Iridium and Platinum tipped spark plugs are designed to operate under normal vehicle operating conditions for up to 100,000 miles (160,000 kilometers) without periodic maintenance. As stated in the owner's manual, maintenance needs may vary because of all the different ways people use their vehicles. As a result, more frequent inspections and replacements may be needed if the vehicle is operated in extreme conditions.

When no engine performance concerns are present, Iridium and Platinum tipped spark plugs should not be removed for periodic inspection and cleaning of threads, doing so may compromise the spark plug's ability to withstand their corrosive environment. The threaded area, although not sealed, serves as a protective environment against most harmful elements. Removing and cleaning spark plugs will introduce metallic debris and brush scrapings into the thread area which may further the corrosion process.

Chromate coated spark plugs should not be wire brushed or handled in any way once they are put in service. Chromium topcoats form a protective oxide on spark plugs that is not effective if scratched. Both coated and uncoated spark plugs will have the best chance of surviving a corrosive environment if they are left in position. Attempts to maintain spark plugs by removing them and cleaning the threads can actually create the corrosive condition that the procedure was intended to prevent.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

Doing so can also potentially lead to issues. So leave them alone unless you're completely changing them...

So, in summary, GM specs a platinum NGK PTR4B-15 for an SSEi. It WILL work in your engine and it is the specific version for your engine. If you feel it is for some reason insufficient, and you will sleep better at night knowing you purchased a better plug, purchase the Iridium verson. GM is fine with it.

[MKMike]

No, my statements are not inaccurate.

Platinum is a harder metal than copper. Iridium is a harder metal than Platinum (both harder and stronger than Platinum). The harder the metal, the higher the resistance for the metal, the higher resistance, the more power from that coil is needed to fire that plug at that gap.

For a S/C engine (or any forced induction engine essentially), especially as you increase boost, it is sometimes recommended that you reduce the gap to avoid potential flame kernel blowout. Meaning OEM boost, on an OEM intake, on an OEM pulley, etc, etc. .060 is fine. However once you start modifying, adding boost, adding air intake volume, etc. this needs to change. Change perhaps to a colder range plug if neccessary, as well as a smaller gap.

THIS is where people may be getting what they're calling "pre-ignition". Running a colder heat range plug and/or running a too large gap for the amount of boost, which translates into higher cylinder pressure, causing potential blowout, leading to a stumble and/or misfire.

As I also mentioned, and then AJ reiterated, any "pre-ignition" is picked up by the Knock sensors, and knock retard dials back timing. Some level of KR can be acceptable at WOT. This is a whole different conversation though.

Your comment about GM's LIM/UIM issue and not being able to trust them with spark plugs on your engine is unfounded. GM has a lot of highly intelligent individuals that are engineers that create this stuff and they do a lot right. At least they get a lot more right than their failures otherwise they'd be out of business. And truth be told, I'm going to trust them first with what they tell me to put in the product THEY designed.

With that said, GM lists this for 2000 Bonneville's (and I know it's repeat information);
VIN K (RPO L36): Plug AC Delco 41-921 (a Platinum Plug), gapped @ .060
VIN 1 (RPO L67): Plug NGK PTR4B-15 (a Platinum Plug), gapped at .060

I do appreciate the further explanation.
It is certainly understandable that a modded engine would require a different heat range plug and you're probably right in surmising that the reported issues with platinum tip plugs came from those owners.
I don't have an Alldata subscription, so I did not know if GM recognized and addressed issues with platinum or iridium plugs.

Didn't intend to slam the intelligence of GM engineers and it can be argued that often issues that occur in production vehicles are due to the bean-counters winning out in the debates on quality levels, at least sometimes.
No doubt it is a very delicate balance, particularly with the added burdens of complying with the ever-changing government regulations and high labor costs.

IMHO, the LIM/UIM issues are an example of a problem which should never occur in a well maintained engine.
The fact that they are expected to fail, often before 100K, tells me that either the engineers goofed or management decided that the cheaper option was worth the risk.
Does any vehicle manufacturer currently use plastic engine gaskets, to your knowledge?

As for the ubiquitous water leaks, some blame can be placed on the fact that the vehicles are aging but I believe it is fair to attribute at least part of the blame to some design flaws.
Love my Bonnevilles, for the most part but there are some problems that just seem ridiculous.

[crash93ssei]

One more thing to add is the confusion I see above about OEM parts.

OEM = Original Equipment Manufacturer. This is simply saying that AcDelco, NGK, Delphi etc are just the companies that made the original part. A part you buy tagged as OEM will not necessarily be the original part that came on the car.

OE = Original Equipment. This means you are buying a part that is an original factory part made by the OEM and should be the original part number.

[MKMike]

One more thing to add is the confusion I see above about OEM parts.

OEM = Original Equipment Manufacturer. This is simply saying that AcDelco, NGK, Delphi etc are just the companies that made the original part. A part you buy tagged as OEM will not necessarily be the original part that came on the car.

OE = Original Equipment. This means you are buying a part that is an original factory part made by the OEM and should be the original part number.

Great info!
Thanks.

[redzmonte]

Irridiums are the way to go. I have had bad luck with Coppers (fail quickly and gap opened up on all plugs). Irridiums and no problems. I have ran platiums on my other boosted GM cars without any issues. but everyone has an opinion... Irridiums last longer and work great so no reason not to run them.. They are pricy compared to others but you get the life out of them and you dont have to spend the time swapping them..

S

[1oldman]

is gonna fire and get hot, the electrode of any plug, be it Platinum, Iridium, Titanium, Plutonium.

CALLING DOCTOR TELLER, CALLING DOCTOR TELLER!! Hummm. I thought close only counts in horse shoes, hand grenades and nuclear war. OOOPPPPS, we're talking spark plugs. SORRY !!!!!!!!!! just trying to add a lil levity and be a sa at the same time. - BC