Help spark plug indexing
 

So I'm somewhat stuck. Everytime I use my snap on trq wrench set at 23nm, my plug is not indexed right. What gives? If I try 34nm it ends up being in the needed 45* angle. I'm using the bosch plugs that fcp sells. But if I use the trq wrench and set it to 45* it ends up being indexed correctly, but is then overtorqued. What am I doing wrong?

nothing. I always order 10 plugs for this reason...

wait, you know there is only 90° of "bad" and 270° of "good", right?

So are the plugs not reusable if they have been over torqued?

not necessarily, you're just squishing the copper gasket the more you torque it. I guess, if you were to overtorque, release and retorque to the proper torque and it's in the correct window, use it

basically, the strap can be anywhere from 1:30 to 10:30 (in respect to the 'hour' hand) since the injector is at 12 o-clock. you need to leave the 90° from 10:30 to 1:30 clear of the grounding strap so as not to interfere with the flame front propagation.

someone was buying different copper washers and indexing their plugs, but that seems a little extreme to me

If I tighten at 23nm it is between those area(clock hour hand). For example i did cyclinder 1,torqeued at 23nm the plug was facing the front of the car towards the bumper. Is that right?

If by "plug" you mean the grounding strap, then yes, that's fine.

No, ground strap is facing the rear of the car, the open part faces the front of the car, while the injector is to the right of it at 3 o clock

that is fine, you just don't want the strap between the tip of the plug and the injector.

just for reference, let's make sure we're on the same page. let's look at it this way:
When you look at the plug, look at it from the side of the engine so that is is extending out in front of you, horizontal to the ground with the strap facing away from you. Now, think of the circular shape of the plug as a clock face. Your strap is facing the rear of the car and open to the front of the car, so lets call the strap 3 o-clock. The injector is directly above the plug at 12 o-clock. so, like I said before, thinking of the plug, your strap(3 o-clock on the example) is okay to be anywhere within the 1:30-10:30 area, so it does not block the spark from reaching the fuel being sprayed by the injector. Does that make more sense?

Here's a few other resources about indexing plugs on the M157... as nota_amg said and many others have, you will probably want to buy several extra plugs as there are very minor differences in the plug thread position which can impact the indexing even if you follow the spec and torque to 23nm.... my buddy is a MB master tech and he's stated this is definitely a tricky process but if you order extra plugs you should get enough of the ones that line up properly.

https://mbworld.org/forums/attachmen...g-indexing.pdf
https://mbworld.org/forums/w212-amg/...ark-plugs.html

I looked at all that. Maybe I'm just over thinking this and trying to get everything in spec VS just put the plug in, torqueing to 23nm and call it a day

You're over thinking it. Install MB spark plugs at MB specified torque. That's all.

Are these not MB spec plugs?
https://cimg6.ibsrv.net/gimg/www.mbw...58524de753.jpg

I don't know. Buy them from MB of Naperville. They have an online parts ordering, carry good inventory and have fast standard shipping. I just ordered rear brake parts from them and it was a good experience and fair prices. My local dealer price for the brake parts was 50% higher than Naperville.

If you use anything other than MB spark plugs, you will chase your tail endlessly on the torque vs angle/position. With MB plugs, they are made to be installed with the correct torque, and the acceptable position is the result. In other words, follow the instructions.

Yea I think il just do that. 158 with tax for a set of 8.dont think I can go wrong with oem. Do I still need to gap them or these are good to go?

Ok figured it out. Stupid torque wrench wasn't calibrated right and it was set to 23ftlbs instead of 23nm. Re-did everything over again and everything is within spec

Don't gap spark plugs. Forget anything you may have learned from working on 1980 Chevys and Fords. I had to do this myself.

nevermind...

What does this suppose to mean 😅

That is wrong, and dangerous. You obviously have no idea what the M157 needs or requires to run properly. Spark plug gap is CRITICAL in the M157/M278, especially if they are tuned.

Tuning has no relevance for me. MB specs as documented are relevant to me. If an owner tunes, caveat emptor.

These are OEM plugs from FCP for 2016 E63 AMG s -- I checked at the dealer once I got them.. so the kit you have has these and they're good.
The advantage with FCP.. you use these for 10-20K miles with your tune. Take them out - send them back and they send you another set for free.. :)

Description

Details

• SKU: BOS-0242140521
• FCP Euro ID: 516992
• Made in Iridium
• Quality: OE

All of them torqued at 23Nm ended up with open face at like 10:40 PM so I overtorqued by 0.4 Nm to end up at 11:30 - yes OCD ..

I may be misunderstanding you here, but there is 90 degrees of acceptable plug angle, with the open face of the plug towards the injector. Your statement seems like the bad and the good are backwards.