@TECHNICIAN hey sorry to bubble up this old thread on plug indexing but wanted to ask if you could confirm something based on the MB photos of the proper indexing here where the open side of the electrode must face the injector per MB.

***Based on the MB photo above - is the injector (not visible in the photo) located ABOVE the spark plug hence the plug electrode open end is correctly pointing up around the 12 o'clock position if looking at this from the side/fender? My apologies for being confused but I really appreciate your feedback here. Thx JV

Yup. BUT, the injector is staring you in the face. That little dark nipple that the open end electrode is sorta pointing at. Also, intake valves are up/inboard. Exhaust valves are down/outboard. UNLESS you have a 4.0, then everything's upside down.

thanks @S63C4 I feel like a dummy as I assumed dark circle/nipple in the photo was injector but was confused... Mine is a w212 / M157 (not 147!!!!) would be as you stated intake values up/inboard and exhaust values down/outboard.

found this video from MB explaining the M157 engine ( ) and at the 2:45 min mark shows some very clear animation of the injector/plug position .

thanks again and apologies for the novice question :)

You need some sleep. Your E63 has an M157, so I'm hoping that M147 is just a typo, or else you have Essen wheels on the brain.

BTW, I ended up pulling the Iridium plugs after the heads were torqued onto the block because I opted to go with Ruthenium plugs instead. The ones I used (LKAR8BHX) are supplied with soft crush washers installed instead of hard copper. Every time I reached 23nm, I yelled out, "GOD, I LOVE CRUSH WASHERS!!" Every single plug was indexed at 12 o'clock on the dot! SO DAMN EASY to adjust torque/index! I used one indexing washer because one plug just wouldn't hit 12 exactly and I'd run out of crush. The Rutheniums have been absolute beasts for 800 miles and yeah, I've pushed it early, but it's fine. With 1050 HP and 1010 lb ft of torque and WMI with a BOV and the MCT 7 full of racing clutches, I challenge anyone to break it in gently the entire 1000 miles! Damn, this car is SO MUCH FUN! I only wish it did what Weistec advertised, but 2.7 seconds 0-60 is an outright lie. It's impossible.

BTW... Seen that vid over a year ago, but ty.;)

Ha yes @S63C4 i do need some sleep and should wear my glasses when I'm typing!!! Appreciate the heads up on the NGK Ruthenium plugs (https://www.ngk.com/ngk-91784-lkar8b...henium-hx-plug) and awesome to hear they correctly index with the MB spec torque of 23nm. I would also YELL out like you my love for crush washers if these suckers index that easily and correctly since guys like us with tuned M157 motors gotta be changing the plugs every 5k-10k miles and its a PITA job! Your S63 is a monster congrats cannot imagine what that power must feel like! Not many tire set ups out there which can handle that much power on a car like yours!!!!

Super appreciate your feedback I may buy a set of those NGK Ruthenium plugs and give them a shot as my 15 E63S has a AMS tune on 100 octane with BB intakes. It dyno'd 746 whp and had zero misfires until the last couple months but the current NGK plugs are at 12k miles (total miles 49k) and waaaay overdue for change!

Proper indexing is one thing, but changing plugs that are made to run 100,000 miles at 10-15k is just a silly waste of time and money. Until I see a sign, repeated more than once that the plugs may be misbehaving, I'm not touching them.

As I said, my car is NO FASTER off the line than it was before the Weistec infusion. The torque limiting cannot be reduced enough to get the 4 wheels to break loose, so I could be running bias ply Korean sneakers on it and never smoke 'em up. @ 24 mph, you get SUCKED into the seat, HARD, but 0-24 is granny drive time and there's NOTHING you can do about it, believe me.

Your 212 is RWD, I'm pretty sure, so you don't have the forced limiting that 4MATIC demands. I only wish I could convert to RWD and have some REAL fun, like you do. I bet you'd beat my 0-60 @ 3.8.

@jvakos has a 0-60 with 60ft of 2.8 ...he's got a 2015 4matic e63 as he mentioned; I have same intakes and dyno tune and have same dragy performance data... tcu tuned by edok

https://cimg2.ibsrv.net/gimg/www.mbw...7f2329d6d.jpeg

SWEET! I'm jealous as hell because an S class can't be tuned to do that. WTF!?! Even Weistec said, "The S63's a boat! If you wanted 0-60 times you shouldn't have gone with large turbos made for top end speed, you should've bought an E63." Ya, like there's even a comparison!! P-LEEEAASE.

Race start doesn't help?

It's an S63, not a CLS63.

Oh I didn't know they didn't put that into an S platform vehicles.

@Duckstu - thanks for sharing your findings here on the OEM plugs and indexing issues... Am having the same issue where the FCP purchased MB OEM #A004-159-81-03 plugs will not index within the acceptable MB range (45 degrees either side of the injector - or 12 o'clock position. So far I tested 6 different plugs on both cylinder 1 and 2 and none will index beyond the 9 o'clock position with the open face of the plug.

These plugs came in a little MB box with a damn MB star printed on it and the FCP site says they're guaranteed to fit. Also called my dealer they said these are the correct OEM MB plugs that should index property.

Product Information (https://www.fcpeuro.com/products/mer...des-0041598103)

This Genuine Mercedes spark plug specifically designed for the Mercedes M276, M278, M157, M152 direct injected engines and it's variants.
The threads in the spark plug and in the cylinder head are calibrated in such a way during the production that the correct installation position is guaranteed

• The spark plug has a copper sealing ring that maintains a defined and small clearance even after repeatedly correct assembly measures
  
• Proper installation torque must be used 23Nm

I was considering trying different washers (per the above) but didnt want to damage the plug threads trying to wrestle the washer off so am giving up on these MB OEM plugs.
I just ordered the NGK 1555's which my indy previously installed and every one was indexed perfectly at the 12'oclock position so will report back on how that goes.

Am simply trying to follow the MB recommendation here and perhaps the index facing 9 o'clock is not that big of an issue, but being tuned I dont want to take any chances.

Appreciate all the sharing on this "indexing" topic that is giving some of us DIY folks headaches

There was someone in a previous post(possibly this thread) that stated that it’s almost impossible to get the proper indexing because none of the components that affect it(plug and head) are perfect. And they said it’s ok, they haven’t noticed any performance loss. If there is, it’s probably a few HP at the most.

Its not the power loss concerns from a incorrectly indexed plug, my biggest worry is about the potential for piston or cylinder damage as MB states “could happen” if outside the acceptable range. May just leave them as is (close to 9 o’clock position) and closely monitor to see if any misfires or issues and call it a day.

I’d be curious if they were indexed correctly out of the factory in our cars and by MB dealership mechanics whenever changing them for E63 owners - have actually correctly indexed them during that service.

The fact that the correct plugs don't index properly at the 23 nm tells me there is more to this than what Mercedes are claiming via bulletin. That, or there's actually less to this...

Seems more like a bulletin to get out of warranty work. Problem is, we can't afford to ignore the information given how sensitive these M157s are.

I have talked to multiple mb techs(my cousin works for mb in Germany) indys techs and each one says that the trq spec is what they all look after. The indexing part is something that no tech looks after as it's next to impossible for all 8 plugs to be indexed right(especially when Mercedes says "when torqued correctly they will always face the right way).

I to have tried multiple torque wrenches to achieve this thinking the issue was my snap on torque wrench, after a few tries I just started to get frustrating at the end of the day. Had 10 Bosch plugs not face the right way, does this mean the whole box of plugs is a waste now??

I'll get my NGK1555 plugs tomorrow and hopefully will report back positive results on my 2nd attempt at correctly indexing since the MB OEM Bosch plug didnt work out :)

Out of curiosity I may go ahead and order a few single OEM spec'd plugs from the different manufacturers to see which index propertly...

MB makes it sounds like its magic or something to correctly index M157 plugs, but net net if the threads dont line up then no matter how close to 23NM you torque it the plug will never line up unless you grossly over / under torque them.

I have been assuming that slight deviations in the torque could at least get within that 90 degree range. If people are saying the torque often yields about 45 degrees off center (the limit) then I think my statement is probably correct.

I've personally tried with my heads off to tq to spec and index plugs and it's absolutely impossible to have them all perfect . There's no way anyone should waste time trying. I've never seen an engine fail from not indexing. For me it's an excuse for them not to warranty. Stock plugs tq to spec don't index. So the bulletin is pointless . I ran Hks plugs gapped to .26 facing the opposite wAy and stock factory plugs for over 40k miles on an aggressive tune, and never had an issue . I think personally everyone is over thinking this. Just get plugs gap them correctly and call it a day. What's actually plays the biggest role is plug gap. The biggest you can put that won't get spark blow out from incoming boost .it's well documented that the biggest gap you can run in your setup will net the best performance. Everyone runs .22 because it's seems to be the go to number that was passed down from previous venders that ran plugs that were colder. I as well did .22 put just didn't like how my engine responded. Idle was a bit funky, slight missfires, I noticed the plug would look as if it was over heated. So I went up to .25 and right away the idle felt smoother, car didn't have mysterious misfires, and when it was time to service plugs I didn't get the same signs of a plug that looked over heated. They looked great!, so I decided let me
bump up to .30 just for a test to see if I will get any misfires or any negative effects going to a much bigger gap opposite of what's been the so called go to gap. Well the car ran great again, no misfires no hesitation. The ran perfect. I did multiple 60-130's ran multiple 10.3 quarter mile runs back to back and while running a **** ton of methanol. So to date my plug gap is and will remain .26 not to big not to small , just right. If anyone is running .22 and your having bad idle issues or unexplained misfires you can't find. That gap may be your problem. Again I know what's good for me may not be good for others but im just giving you guys my opinion from what I've done. I definitely don't expect everyone to agree with me but I suggest you give it a try or perhaps do some research on your free time and look up plug gaps indexing etc. I'm not saying indexing doesn't have merit or pros, but for this engine I don't see it.

This is exactly the post I’ve been waiting for. For me, I’m just going torque to spec and call it a day. I believe mine are running factory gap as is. Once the time comes for me to replace these plugs, I’ll try a more conservative gap like yours.

Currently running factory gapped plugs on my car and have had no issues for the last 25k miles with plenty of hard runs and pulls. I torque mine all to spec and fortunately for me, they all indexed pretty close to what's shown in the diagrams presented here.

Tuned?

said I would report back on my install of the NGK 1555 plugs….finished them last night and am VERY pleased to report they all indexed within spec with 23NM of torque. All we’re positioned either just to slight left or right of the 12’oclock position (electrode open end facing up towards injector).

The OEM Mercedes Bosch plugs that I attempted to install on all eight cylinders faced either 9’oclock or 3o’oclock at 23NM torque (digital torque wrench used). That is still pretty close and likely fine but technically still outside the MB spec per the documentation.

I bought the NGK 155 Plugs from Rock auto for $14 bucks a plug as well which was the cheapest of any website for those. They were the plugs that my Indie guy installed just prior and lasted 12,000 miles on a 100 Octane race fuel tune and had zero misfires until the past couple months since the plugs were pretty black especially cylinders 1 and 5.

Im an amateur with wrenching on my M157 but happy to share any feedback on the process for those who attempt this. Not required, but I would definitely recommend buying that Hazet plug socket on amazing for $55 bucks it is the perfect depth for the cylinder and the swivel goes to full 90 degrees to help you easily get it into the far plugs 4 and 8 by the firewall.

Yup, stage 1 tuned from ECC.