izzyz28

Hi all. At 64,000 miles I am in need of a fresh set of plugs. I've searched the forums/internet for a while and found a little information on spark plugs for the 55 cars.

1. It looks like the original plugs are NGK ILFR6A.
2. Bosch makes the FR6MPP332 which supposedly fits.
3. It also looks like every parts store lists the NGK BKR(or BRK, can't remember) plugs, which are incorrect.
4. The correct plug reach is ~28mm(over 1 inch), while most plugs listed for these cars are 3/4" reach
5. The two correct plugs listed above go for ~$11 apiece, which works out to ~$180 for a set of plugs.

My question is, does NGK/Bosch/Anyone make a standard copper or single-platinum plug that works properly for the 55's? I don't mind changing plugs every 20K or whatever it takes, but I do mind spending almost $200 on a plug change. I would imagine that at least NGK would offer a 28mm reach standard copper plug for $2 that will work in these applications.

If I am incorect or crazy please tell me, but I am getting nowhere with internet searches. I would love for some members with REAL experience chime in on this and tell us what they are running, how well it works, plug change intervals, etc... Thanks!

komp55

Factory specified plug change interval is 100,000 miles. Some guys have changed them sooner, and some guys have installed one step colder plugs.

Given the change interval, spending $180 for a set of plugs seems pretty reasonable. There's no sense in putting in some cheap plugs when the factory specified NGKs work so well. I'd say if you're worried about spending $180 for a set of plugs, the E55 may not be the right car for you. These cars love being pampered with money and mods.

ohlord

NGK 7090 single side electrode platinum plug.
.039 gap use no anto seize,they are bivalent plated.
$3 each last 100k
bosch 7422 about 4 bucks.
M113 engines love them.
Do not use pricey multi tip plugs,m112 and m113 engines hate them.
do you have the metal boot wires?If so you will enjoy the plug change and not damage the wires if you use the 17mm mercedes boot tool
pm me if you need one.
Free phone support
Have you had the transmission fluid and filter changed or will you be doing it yourself.722.6 fluid only.
If I were you that would be my primary focus,well before changing out 100k plugs.
I have the special dipsticks and pan magnets also.

chiromikey

+1! considering the change interval for a set of "good" plugs, there's no reason to worry about the cost.

izzyz28

Thanks for the replies so far! It's not the outright cost of the plugs, I can easily afford it. However, if there is a single-platinum plug available such as the NGK ohlord posted, I would rather use it. Call it principle or whatever you want, but that's what I'm looking to do. I appreciate all comments!

Though the factory plugs are SUPPOSED to last 100K, I am experiencing rough idle on cold startup, and through searching have found that other board members have experienced the exact same thing at around 60K miles and fresh set of plugs did the trick. I do have the wires with metal sheath, so barring a broken wire I am going install fresh plugs and use the stock wires. If the plugs don't fix the issue I'll get a set of the aftermarket wires(can't remember the company name, Evosport??) that seem popular here.

I will service the tranny very soon, that is on my list of things to do. I will keep ohlord in mind if I need /when I need the dipstick/assistance.

Komp55, I know these cars love money and mods! This is part of reason I don't want to dump a ton of money into plugs. I'm going to use the stock heat range for now, and if/when I go for a pulley and tune I'll likely go one heat range colder.

I mainly started this thread to get all of the GOOD spark plug information in one place. Keep the comments coming!

Edit: It looks like the 7090 is a 3/4" reach plug. I've heard that these will not work. I would imagine the electrode would sit inside the spark plug hole instead of the combustion chamber. Can anyone confirm/deny that the correct plugs are 28mm reach? If that is the case I will simply buy the proper ILFR6A Iridiums.

TexasSteele

I used:
http://cgi.ebay.com/ebaymotors/ws/eB...ht_4231wt_1606

But think I paid just under $100 shipped during a 10% off ebay sale... FCP has top quality parts and super quick service/shipping. I used them all the time buying for my m5.

Also recommend:
Magnecor 8.5mm wires
http://www.alamomotorsports.com/Magn..._mercedes.html

85240 2005-1998 4.3, 5.0, 5.4, 5.5 - M113 V8 engines, $169.43

For under $300, you'll be in good shape for the next 50-100k miles. And only need to do the labor once. Threading 16 spark plugs into 16 aluminum threaded holes isn't something I'd want to do every year.

Also-I will say a spark plug is a spark plug, and I've been tempted to try the new NGK offering. Especially with dual plugs, I don't know if platinum performance is really necessary (and I need 1-2 heat ranges colder for the big nitrous shot).

izzyz28

TexasSteele, thanks for the links. I used to work for Bosch, and the spark plug application engineers would readily admit that +2, +4, iridium, etc... was a load of marketing crap. There is a huge difference between copper and platinum, but there is no benefit going from a $3 platinum to a $10++ iridium.Knowing this, I thought I would look into alternatives.

Were the plugs from FCP the correct reach? When you had the plugs replaced, did they compare favorably to the original ones? I ask this, because I have seen the incorrect plugs listed for the 55 cars from many vendors.

TexasSteele

Right on to the thread indexing...different brand, but other than that seemed to fit very well. If I hadn't spent all day yesterday in the car I'd go pull a pair and snap a photo...actually still might.

I'll agree on the marketing on +2+4 +12, etc...but at $6.25/plug I thought why not.

I'm very pleased with the magnecor wires, even without the metal heat shield on the plug boots.

AZIPOD

I replaced all 16 of my plugs with Bosch FR6MPP332 at around 51k miles. The engine is noticeably smoother and got about about .5 mile more per gallon.

I don't go for the 100k mileage thing. I feel it's somewhat of a marketing ploy. It'll go 100k, but you've already lost a lot of its spark efficiency by half that time. I'm not a technical expertise, but I'm just going with personal experience.

Either way you look at it, 100k miles is A LOT spark cycles and heat for one piece of spark plug to endure. The plugs are not expensive ($10 x 16) and you can do it yourself at home with basic tools. Budget for 2-3 hrs for a first timer. Don't we all love working on our cars?

TexasSteele

Glad you mentioned the reach...I checked the indexing at full thread, and they were all within 10* of each other...

But seems the Bosch plug is about 6mm shorter

TexasSteele

Sorry for the Treo camera phone pics...all I had handy. And I refuse to buy an iPhone

And at 95k miles (car has 98k on it now) I didn't notice a big difference. I did install the plugs, wires, headers, remove the secondary cats and resonator/silencer all at once...and it made very little seat of pants difference.

I'd say the strongest pull since the changes has felt better than the strongest pull before, but thats looking for a sub 75 degree cool dry night in Texas.

izzyz28

Thanks for the pics! It looks like the Bosch plug is noticeably shorter. It may not affect performance, but if you ever try to install the 28mm plugs, the last few threads in the head will very likely have some carbon stuck to them which can and will cause problems. I've seen this happen before on other cars.

As far as longevity, 100K is a ridiculously long time. On an N/A application I could and have seen plugs go that long, but with forced induction and a heavy foot those plugs are going to erode a LOT faster. This must be why several people are experiencing a rough cold idle at 50K-60K.

TexasSteele

The OEM plugs I'm guessing had 95k miles on them, and you could see in that pic (better on other plugs removed) that it looked like some oil on the threads. May have been carbon. If only we had someone on this board with a cylinder head off the car...*ahem* anyone???

mekantor

Here is a photo of the Bosch FR6MPP332 plug next to the plug I pulled out of the engine.



The old plug has the Merceds logo on it, does that mean its a factory original, or would a dealer-replaced plug have that logo on it as well?

AZIPOD

It also depends. Not too long ago, I replaced the front pads on a BMW. There were two options for "factory" pads.

First Option: By OEM from Jurid or Textar. They came in plain boxes and were priced around $40.

Second Option: By "Genuine BMW" from the dealer. Those came in a pretty box with a BMW propeller logo on it. Cost? About $65!

The pads were exactly the same. But the ones from BMW did have a BMW stamp on it. Not sure if it was worth the extra $25!

mekantor

Good point. The thing is that the old ones are NGK, and the local dealer said they use Bosch for their replacement plugs, so I assumed that was true for all NA MB dealers. They quoted me at $35 for EACH sparkplug

izzyz28

I ended up getting the original NGK's from Advance Auto Parts. Total price with tax was $173. I think it was $9.99 a plug. Changing them was easy, did it in less than 2 hours(warranty book time is 2.2) but unfortunately it didn't fix my rough idle, so I have no idea what's going on with the thing. It runs fantastic otherwise!

mekantor

So did you go with the ILFR6A plugs? I called all the local stores and no one had plugs in stock for the E55, at least according to what their computers had listed for the engine. Mine were purchased through rockauto.com, paid ~$180 shipped but got 20 plugs because they are sold in packs of 10.

PDC

izzy - Can you tell me how in the heck you were able to reach the 3 plugs closest to the firewall on both sides of the motor? Did you use a special tool to get ahold of the boot?

I recently tried to swap plug wires myself - not even the plugs, just the wires - and (embarassingly) had to 'tap out' and let my dealership do it for me!?! I'm no certified mechanic, but I know my way around the garage, having done far more extensive work than plugs and wires in the past. It wouldn't have donned on me thta I would have had any trouble at all swapping out a set of plug wires. I couldn't reach the boots for the back plugs and the boot removal tool I had was like trying to sew a button on a shirt with a hunting arrow. I can't imagine getting a plug socket back there. What am I missing??

Thanks!

JoelE55

chiromikey

check your motor mounts. even if they're not completely broken they can still cause a rough idle.

mekantor

What I used for all plugs was a deep socket (16mm I think) attached to 3" extention, both 3/8".

For the wires, get a 17 or 18mm wrench on it, and put apply some leverage against the valve cover, there is just a bit of resistance and then they pop off.

mekantor

Nice! Now I know what plugs I removed.

izzyz28

Hi all.....

I went with the NGK ILFR6A plugs from Advance. I walked in and told them the stock number(3588). They tried to look up the application anyways and of course their listing was wrong. They had to get them sent in from a couple differnet stores, but I had them the next day.

As far as getting the wires off, I used one of those insulated plug wire removal tools(probably $10 at any store), which got them all off no problem, even though they were really baked on.

The plugs came out with nothign more than a standard 5/8" plug socket, a 3" extension, and a ratchet. Even the back plugs were super-easy this way, no swivels or trickery required. Good luck!

prodigymb

yup. advance does have the lowest price on these around !!

http://shop.advanceautoparts.com/web...GRPTUNEAMS____