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Hello - I've seen a number of posts that explicitly advise against using platinum and iridium plugs in e28s, but I haven't seen much explanation beyond that. A mechanic I trust said definitely stay away from Platinum but that Iridium might be an upgrade.

What are the problems with Iridium plugs in these engines?

Thanks!

They are designed for cleaner burning engines, i.e. newer cars. They will have a good chance of fouling out if used on older, less classy vehicles.

Kyle in NO wrote:They are designed for cleaner burning engines, i.e. newer cars. They will have a good chance of fouling out if used on older, MORE classy vehicles.

See typo correction above

Kyle in NO wrote:They are designed for cleaner burning engines, i.e. newer cars. They will have a good chance of fouling out if used on older, less classy vehicles.

But what does this really mean? More valves? higher compression? Got a buddy running them in a 91 audi with great results. Apparently these are designed to fire on lower voltage because of the nature of the material.

Has anyone here run them on an e28?

Why not use the plugs that were designed specifically for these engines? The iridium shit is simply a sales gimmick. Ooooooo, they sound exotic! Let's spend $10 each on them.

Parkinen wrote:

Kyle in NO wrote:They are designed for cleaner burning engines, i.e. newer cars. They will have a good chance of fouling out if used on older, less classy vehicles.

But what does this really mean? More valves? higher compression? Got a buddy running them in a 91 audi with great results. Apparently these are designed to fire on lower voltage because of the nature of the material.

Has anyone here run them on an e28?

I ran a set of NGKs on my 535 for 45K, and passed smog at that mileage. Cali dyno smog including Nox. Isn't that good enough? I think the Platinums, and I'll include the iridiums with them as I think they're relatives, are really best used on coil pack cars, not on distributor cars with a single coil. What do you hope to achieve with them?

Overpaying for plugs. Hard to beat $2 and change for a spark plug. Especially given how long they last.

Mike W. wrote:

Parkinen wrote:

Kyle in NO wrote:They are designed for cleaner burning engines, i.e. newer cars. They will have a good chance of fouling out if used on older, less classy vehicles.

But what does this really mean? More valves? higher compression? Got a buddy running them in a 91 audi with great results. Apparently these are designed to fire on lower voltage because of the nature of the material.

Has anyone here run them on an e28?

I ran a set of NGKs on my 535 for 45K, and passed smog at that mileage. Cali dyno smog including Nox. Isn't that good enough? I think the Platinums, and I'll include the iridiums with them as I think they're relatives, are really best used on coil pack cars, not on distributor cars with a single coil. What do you hope to achieve with them?

I feel like I've read some posts warning against these plugs, but don't ever really hear why. Then I read another post of someone claiming performance gains from a different type of plug and people say its all imaginary: A plug is a plug - if it provides consistent spark it works - no performance gains to be had. These two approaches seem to contradict each other. If a plug works it works and the real measure seems to be longevity and consistency, which these Iridium plugs seem to market heavily. If an Iridium plug didn't work properly to OEM spec in a certain car it seems to me it would behest the manufacturer of that plug not to sell for that specific car.

I guess I'm wondering who's really right...

A Bosch WR-9-LS is $6.50 from Pelican Parts and an NGK IX is $7.00 at my local shop. If the NGK iridium works and gets significantly better longevity, then that's that. If a plug works a plug works, right? If there's anyone out there that's actually used these and had bad results I would love to know. Otherwise I might give em a whirl! Measurable consistency is good in any electronics application. Is there data out there that proves that OEM Bosch silver of copper plugs provide the best bang for the buck? <-----Ignition pun intended.

Parkinen wrote: Otherwise I might give em a whirl! Measurable consistency is good in any electronics application. Is there data out there that proves that OEM Bosch silver of copper plugs provide the best bang for the buck? <-----Ignition pun intended.

I'd say go for it and provide our first data points. You may be starting a trend. Which model number are you thinking of using?

seeing the post title, I was expecting a connector problem with one of these.

waynet1 wrote:seeing the post title, I was expecting a connector problem with one of these.

that was a good chuckle.

demetk wrote:

Parkinen wrote: Otherwise I might give em a whirl! Measurable consistency is good in any electronics application. Is there data out there that proves that OEM Bosch silver of copper plugs provide the best bang for the buck? <-----Ignition pun intended.

I'd say go for it and provide our first data points. You may be starting a trend. Which model number are you thinking of using?

Got a set of NGK BPR5EIX for 6.99/each at Oreilly. I'll throw em in and see what happens.

No data, just experience and and hearsay. I get about 40 K from coppers and 80k from silbers. I could have gotten more from either. Ron Webster got 150k out of a set of silbers. I switched to NGKs simply because Bosch quality has slipped in recent decades Platinum and iridium are less conductive than silver or copper. Fine for a modern high voltage ignitions, not so much for lower V single coil systems

a wrote:Platinum and iridium are less conductive than silver or copper. Fine for a modern high voltage ignitions, not so much for lower V single coil systems

This is helpful.

As I understand it Platnum and Iridium plugs with the miniscule center electrode are designed for higher energy ignition system which an e28 does not have. Newer coil over systems run higher voltage which will keep these electrodes clean for 100+ miles. In our cars it may run fine or it may foul too easily since there isn't enough energy to keep the tip as clean of deposits. Sort of like matching the bulb voltage to your flashlight.. 2 cell, 3 cell and so on use different bulbs. The 3 cell bulb will work in a 2 cell flashlight but not burn as bright. For a spark plug that equates to fouling more easily.

The NGK ZGR5A is the one I use in M20 & 30's.

Found this. May be worth a look - may be unfounded but on first glance it looks legit.

They're saying that because you can make an Iridium tip so much smaller than a conventional plug it actually requires less voltage to ionize and spark.

http://www.weaponxperformance.com/techn ... ECH_V1.pdf

Once burned, twice shy. I put a set of plats in a Bav I had way back when and fouled them in a few weeks. That car was hard on plugs, but that was the only time I ever fouled plugs. A year or two after that in an imported parts store I was talking with the owner and he said he wouldn't even sell them unless a customer demanded them, his experiences had been so poor. Granted E3s had a weaker ignition system than an E28, but my experience, combined with his, not to mention an assortment of stories here, lead me to believe they are not a good product for these cars. IMO, a basic spark plug works fine. A "better" plug may last longer, but won't run any better, kind of like premium gas in an 8:1 compression car. With a good basic plug being cheap, I see no reason to experiment because of a buzzword or some company's whitepaper. The best that can be said for plats is they work just fine. And I'm sure sometimes they do, but they don't often enough for me not to use them.

Mike W. wrote:Once burned, twice shy. I put a set of plats in a Bav I had way back when and fouled them in a few weeks. That car was hard on plugs, but that was the only time I ever fouled plugs. A year or two after that in an imported parts store I was talking with the owner and he said he wouldn't even sell them unless a customer demanded them, his experiences had been so poor. Granted E3s had a weaker ignition system than an E28, but my experience, combined with his, not to mention an assortment of stories here, lead me to believe they are not a good product for these cars. IMO, a basic spark plug works fine. A "better" plug may last longer, but won't run any better, kind of like premium gas in an 8:1 compression car. With a good basic plug being cheap, I see no reason to experiment because of a buzzword or some company's whitepaper. The best that can be said for plats is they work just fine. And I'm sure sometimes they do, but they don't often enough for me not to use them.

Good to know. I guess the real measure of a plug is consistency and longevity through that period.

Interesting that the OP is trying so hard to use anything except what is KNOWN TO WORK after a billion miles for his spark plug.

I understand the curiosity as to why we don't use the latest plug design and the answer is someone tried it and it wasn't any good. But I don't understand the continued desire to go against the grain.

The NGK ZGR5A and Bosch WR9LS are the only two plugs to use in the M30B34 based on the experiences of hundreds of owners over three decades.

The NGK can be had cheap, too.


Why rock the boat? if it will not lead to an improvement (based on past knowledge)?



As to why those fancy fine tipped plugs not working in our cars, maybe it is because our cars are designed to allow oil in to the combustion chamber and this clogs up those plugs but quick. Or it could be something else. We are not at all interested in why and are not going to all the trouble of running a fully monitored test to determine the answer as there are more than adequate plugs available for these motors.

Blue Shadow wrote:Interesting that the OP is trying so hard to use anything except what is KNOWN TO WORK after a billion miles for his spark plug.

I understand the curiosity as to why we don't use the latest plug design and the answer is someone tried it and it wasn't any good. But I don't understand the continued desire to go against the grain.

The NGK ZGR5A and Bosch WR9LS are the only two plugs to use in the M30B34 based on the experiences of hundreds of owners over three decades.

The NGK can be had cheap, too.


Why rock the boat? if it will not lead to an improvement (based on past knowledge)?



As to why those fancy fine tipped plugs not working in our cars, maybe it is because our cars are designed to allow oil in to the combustion chamber and this clogs up those plugs but quick. Or it could be something else. We are not at all interested in why and are not going to all the trouble of running a fully monitored test to determine the answer as there are more than adequate plugs available for these motors.

Where did you find on this forum someone having first hand specific issues with a fine tip iridium plug? I have been unable to locate such a post. Platinum yes.

By the way it seems a little presumptuous to say "We are not all interested in why..." ----just saying

I think it's an honest question: Tell me why specifically iridium plugs should avoided seeing as they:

a) are designed to spark and ionize at much lower voltages than traditional tipped plugs (like the ZGR5A and WR9LS)
b) are typically known to last more than 20% longer than traditional plugs
c) have worked in people's M30 engine already who have shared their experiences in this thread

I can't find the smoking gun, so to speak. At this point all the nays just say they're designed for modern cars and the yeas say they worked fine in an M30. Don't get high and mighty on me for noticing a discrepancy.

So anyway...

If anyone has such an experience, I would love to hear it.

The iridium plugs have a very small center electrode and I believe that this is the reason another small center electrode plug is crap in these motors, not enough surface area to get the spark through was the electrode gets covered in combustion products.

Sure they are the latest and greatest for motors and ignition systems that can take advantage of them. But the M30 uses a 20W-50 oil vs. the new vehicles using a 0W-20. This heavier oil means much wider tolerances, passages and gaps, allowing more oil into the combustion chamber to foul the <1mm center electrode.

If the car runs right with the proper plug, what are you going to get with a different plug? A combustion that is the same as with the proper plug? Or will it provide that extra phenomena of being able to burn more of the fuel in the chamber than is really there?



So give em a try to report back in 60,000 miles how they did. We want to know, but will probably still be using the Bosch or NGK specified for the motor.

Blue Shadow wrote:The iridium plugs have a very small center electrode and I believe that this is the reason another small center electrode plug is crap in these motors, not enough surface area to get the spark through was the electrode gets covered in combustion products.

Sure they are the latest and greatest for motors and ignition systems that can take advantage of them. But the M30 uses a 20W-50 oil vs. the new vehicles using a 0W-20. This heavier oil means much wider tolerances, passages and gaps, allowing more oil into the combustion chamber to foul the <1mm center electrode.

If the car runs right with the proper plug, what are you going to get with a different plug? A combustion that is the same as with the proper plug? Or will it provide that extra phenomena of being able to burn more of the fuel in the chamber than is really there?



So give em a try to report back in 60,000 miles how they did. We want to know, but will probably still be using the Bosch or NGK specified for the motor.

I'm not interested in any benefits I'm just curious what the specific issues are and why. If they get longer life that might mean more consistent operation through a normal range (40-60k???). Like I said, my mechanic buddy said they're designed for low voltage operation, and then some people say they're designed for high voltage coil pack cars. Maybe that's intentional?

I used iridium plugs on my TCDs1 car. Densos, don't remember the exact model. I was tired of fouling plugs and having to clean them to get the car to run right. I also used an aftermarket coil with a pretty big secondary. The plugs never fouled again in the 30-40k miles I had them in there before selling the car. So I know they can work, and do work as advertised in terms of not fouling if you have enough spark energy to light them off properly.

That said, I see no reason to use such tricks on an otherwise stock motor. Normal plugs last plenty long enough on a healthy motor. If you're having fouling problems on a stock motor, it's time to either look at rebuilding what's allowing excessive oil into the combustion chamber and ashing up the plugs or simply getting the thing in proper tune to begin with.

Jeremy

Parkinen wrote:I can't find the smoking gun, so to speak. At this point all the nays just say they're designed for modern cars and the yeas say they worked fine in an M30. Don't get high and mighty on me for noticing a discrepancy.

So anyway...

If anyone has such an experience, I would love to hear it.

No one said they would not work. I think most are saying they may foul more easily and several have passed that experience on. Maybe not in this thread and maybe not specifically Ir versus Pt so who knows for sure what your experience will be. Buy them, run them, let us know. But the combined wisdom is saying that as soon as you have a little trouble with your m20/30 maybe running rich from a bad CTS or O2 sensor you will get fouling and misfires and maybe no start. Then you get to fix that AND clean your plugs. And these things are common with these old motors especially with all the miles on them and no OBDx.

So if none of this ever happens to your car maybe you get extra miles out of the plugs. But since these are not 100k no service engines you should still be doing regular valve adjustments at about 25-30k. I don't think skipping a change of the lower cost plugs every other valve adjustment is a big time and money saver. Maybe even a higher total cost of ownership if you get 3 versus 2 valve adjustments over an NGK ZGR5A for example.

Not trying to be high and mighty but my guess is you are (at this point) less educated about all the other service you should be doing on a regular basis and more interested in fancy new spark plugs. I hope that is wrong and I hope you are learning what you can about these old cars and plan to keep it going. On the other hand maybe you haven't put 10k miles on a 80's BMW and you have a very slim chance of running or keeping this car long enough to see if the Ir plugs will matter. (and if that were true I just made the best case for the cheapest plugs)

Take no offense, it's not intended. The collective wisdom here has helped me so much I don't ignore it. I have 4 80's era BMW's between my son and I that all run great based on what folks here say regarding service and brands and parts.

tn535i wrote:

Parkinen wrote:I can't find the smoking gun, so to speak. At this point all the nays just say they're designed for modern cars and the yeas say they worked fine in an M30. Don't get high and mighty on me for noticing a discrepancy.

So anyway...

If anyone has such an experience, I would love to hear it.

No one said they would not work. I think most are saying they may foul more easily and several have passed that experience on. Maybe not in this thread and maybe not specifically Ir versus Pt so who knows for sure what your experience will be. Buy them, run them, let us know. But the combined wisdom is saying that as soon as you have a little trouble with your m20/30 maybe running rich from a bad CTS or O2 sensor you will get fouling and misfires and maybe no start. Then you get to fix that AND clean your plugs. And these things are common with these old motors especially with all the miles on them and no OBDx.

So if none of this ever happens to your car maybe you get extra miles out of the plugs. But since these are not 100k no service engines you should still be doing regular valve adjustments at about 25-30k. I don't think skipping a change of the lower cost plugs every other valve adjustment is a big time and money saver. Maybe even a higher total cost of ownership if you get 3 versus 2 valve adjustments over an NGK ZGR5A for example.

Not trying to be high and mighty but my guess is you are (at this point) less educated about all the other service you should be doing on a regular basis and more interested in fancy new spark plugs. I hope that is wrong and I hope you are learning what you can about these old cars and plan to keep it going. On the other hand maybe you haven't put 10k miles on a 80's BMW and you have a very slim chance of running or keeping this car long enough to see if the Ir plugs will matter. (and if that were true I just made the best case for the cheapest plugs)

Take no offense, it's not intended. The collective wisdom here has helped me so much I don't ignore it. I have 4 80's era BMW's between my son and I that all run great based on what folks here say regarding service and brands and parts.

No offense taken, I owned an e32 for almost 10 years so I became pretty versed in the general maintenance of the M30 (B35).

I work in an industry that is bombarded by kind of trivial technical improvements that also preys on the pro-sumer believing most of it, so I certainly don't believe marketing until I actually use the stuff. Like I said I just got some differing information and the more I dissected it the more I realized there was a lack of good hard information and evidence (specifically about Iridiums fouling).

The kicker for me was when I read that the Iridium plugs were designed to work at pretty low voltages under traditional Copper of Silber plugs. Which is like the proliferated reason on the forum not to use them. So you can imagine my confusion at that point. Also, I still can't find any posts from people getting fouled Iridium plugs...platinum stories abound.

Anyway I didn't find any answers so I thought I would ask. I still don't know if I've really gotten an answer. Anyone here foul out a set of Iridium plugs in an E28?