rspizzi

So what the verdict on the plugs? Will plugs with a 3/4 ' reach work on a 03 E55 or should I go for the longer plug? I'm leaning towards the Bosch Iridium's,
part #9652, which has the 3/4" reach. Please help!

jpohl402

so, any feedback on the type of plug that works best or that most here use....??

jpohl402

Got some questions regarding which plug to use - could use some insight.....

Went to a friend who pulled up CarQuest auto supply company for repair facilities. Put in vehicle year, info, etc...
About 12 types of plugs came up (though Bosch isn't a supplier)
Very confused as to specs !!!! Need to know which to choose....

ALL 3 are listed as OE Exact Fit - but all different
1. Denso Part 3324 - (Gap??) 0.044 - Iridium Plug - 9.35/each
2. AutoLite part APP5325 - Gap of 0.032 - Double Platinum ?? - 4.66/ea
3. NGK part 3588 - Gap 0.039 - Iridium - 12.06/ea

Thanks for help !!

izzyz28

As far as I know the NGK ILFR6A(3588) and the Bosch FR6MPP332 are the only two that have the proper reach. All the rest, even if they are listed in the catalog(which they all seem to be) for this application are 3/4". I'm sure they work and I know some have used them, but with a shorter reach they will be shrouded by being up in the hole and will leave a few threads exposed to the combustion chamber. I would stick with the two above.

rspizzi

Thanks for the input. I went with the Bosch FR6MPP332. They will be installed this weekend along with the supercharger belt I'll let you know how it turns out.

izzyz28

Great! Glad to help and good luck.

Infiniti

Rock auto has the Bosch FR6MPP332 for 7.83 per plug.

rspizzi

Had the Bosch FR6MPP332 plugs installed and they were identical in size to the original plugs that were removed which, by the way,still had plenty of life left in them at 48,000 miles. So for those interested this bosch plug can be used in our vehicles. By the way, my car is a 03 E55.

AMG903L

NGK Iridium Resistor LFR7AIX

Buxton

At 76k miles I used the Bosch FR6MPP332 and my 2006 e55 loves them. Purchased from rock auto $127 shipped......didn't feel like having the wife nag me for working on my car so I had my mechanic do it for $192. (Only took him 1.5 hour)

The car ripped *** before but now holy crap what a difference. Feels like the ECU reset only permanent.......but very smooth acceleration and much improved throttle response.

Anyone debating waiting for 100k miles forget it I'm so glad I did this.

It's my daily driver and round trip sitting in traffic 96 miles 2 hours 30 minutes after start and average speed only 38 mph and spirited driving when possible 19 MPG achieved........up from 17.7.....added bonus to improved performance!

seven6zero

Sorry to dig up an old thread, but are these still the plugs to go with? My E55 only has 44k miles but are using the original plugs. Idle isn't rough, is just the life span a good reason to replace?

Buxton

I used the Bosch noted above on this thread and still swear by them....82k on the clock now and this car purrs smooth and never hesitates when I punch it.

Max.H

I wouldn't over think it. Spend the money and buy the recommended plugs or a step colder. I did mine already and the car idles smoother butt dyno still feels strong. I don't see the point in changing out 16 plugs often.

The plug wires will start to lose connectivity and thats more money. Not to mention the increased possibility of stripping the threads in the block etc etc. I say why?

Just my 2 cents.

Gadget

I do not think that Denso part number is correct.

That is a 16 heat range plug.

The correct heat range for the stock E55 is 20.

I have upped the power from my E55 and I am using heat range 22.

I use the IKH22 Power Irdium plug.

Just FYI- all heat range 22 plugs from Denso are VERY HARD to come by right now. The demand is out running the production. I have had a 1000 of them on back order since September.

G

RAWAMG

+1

caigarage

hi all, new here.
Just changed plugs on my s/c s55. When I pellud the plugs, I saw they were the original iridium plugs. (which I hate). Sourced outcopper plugs in the same heat range. Ended up with ngk lfr6c 11 specd for Toyota.
Why do I dislike platinum or iridium plugs? As indicated by my handle, I run a garage that specializes in muscle car resto and racing. Dyno and plug testing has shown me time and again that copper core plugs still provide more spark since copper is still a better conductor.

Ended up finding this thread to see if anyone has done the same. Was hoping to see how long copper core plugs would last since this is my first s/c Benz. All my other benzes have run copper core plugs with positive results.

As I expected, the copper core plugs seem to be doing better but then again Im comparing a 9 year old plug to a bnew one. I also did an oil change using monograde 30 highzinc diesel engine oil so improvement would be a combination of fullervice. Bought the car 3 months ago and its the first service ive done.
I do service my cars every six months by the way. Not a fan of 5k intervals either. ( labor is free, parts are wholesale price )

3BNick

I agree. Some cars respond well to copper. On my last boosted car I removed factory platinums for NGK coppers one heat range cooler as well. Car ran great but I found myself changing the plugs every 2nd or 3rd oil change which I'm sure a conservative tune may have played a part in. I have a shop as well so it was no big deal for me especially with plugs going for under two dollars a pop. I have yet to do the 55k plugs but I feel I will follow the heard here and heed the advice of those who have already been there.

Perhaps I may run a copper vs. iridium/platinum plug shoot out.

Gadget

The only part of a iridium plug that is iridium is the very tip of the conductor. The rest of the plug is very conventional.

Using iridium at the very tip prevents erosion of the electrode and provides superior plug life. It also allows the electrode to be made very small for a very focused spark that is very consistent.

If you look closely at the iridium electrode you will see that the iridium part is very short and LASER welded to a larger conductor.

Every dyno test I have seen where the only change was swapping in Denso Iridium plugs has shown an increase in power.

Iridium plugs in aircraft engines has resulted in huge savings from dramatically increased plug life and they are much more resistant to fouling and lead contamination.

G

e55amgrocket

I know the denso 22 heat range stuff is hard to get lately. Figured there wasn't much demand so they don't make that much. I've been using good ole standard plugs and and will continue to do so with the new build. I like to pull the plugs to read them and the new engine will is being built for spray so ill be pulling/reading/replacing a lot of plugs. $1.89 each is a lot easier on the pocket. Nitrous doesn't like iridium anyways

2EASy

You mind posting the part number of the conventional plugs you use?

e55amgrocket

I have different heads but I use BCP7ES.

2EASy

Thanks for posting, but I'm assuming those wont work on stock heads.

advance has a part number: Part No. 6702

http://shop.advanceautoparts.com/web...034%7CL3*16071


wonder if those work

03'55AMG

I just ordered a set too, of the FR6MPP332's. Get here Thursday or Wednesday. Original plugs now, at almost 80,000 miles. Was going to do wires, but figured if the plugs make a big difference, I will hold off on those for now.

Question for seasoned E55 plug changers w/stock heads- How hard should it be to remove the plugs themselves form the head? I pulled a few from cylinder #8 just to peak and the first one (closest to front of car) was easy, then the other #8 plug was extremely difficult. Like I thought I was going to snap the plug.. I hit all the plugs with healthy doses of WD-40s version of PB Blaster, and it helped a lot, on most plugs. Why are these in there so tight? I would hate to damage a head...

e55amgrocket

Yes that's normal. They have fine threads and are .750 inches long so they take awhile to get out. If you have time to waste break them all loose a few turns then spray some penetrating lube on and let them sit. A few hours later they will come out with ease.

03'55AMG

Good Idea! Thanks mang!