Help spark plug indexing
Out Of Control!!
Joined: Apr 2019
Posts: 12,003
Likes: 6,827
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
EVERYTHING IS ABOUT DETAILS
Why does MB insist on not building robust ignition systems??
How many old-fashion details are used against basic performance..??
Last edited by CaliBenzDriver; Jan 29, 2025 at 09:56 PM.
Member
Joined: Jan 2022
Posts: 182
Likes: 70
From: Jersey City
S63 Coupe
I mean... If MB post a bulletin to warn you of the necessity of plug indexing, one can at least expect the plug installed in the factory to be indexed properly.
Member
Joined: Sep 2008
Posts: 92
Likes: 41
From: Rocklin, CA
'14 CLS550 , '86 420SEL
I am about to gap my plugs and I read this on the gapping tool’s instructions
is this common knowledge or do I stick with gap as marked?
- Adjustment Tips: For normal physical phenomena, some spark plugs electrode will spring back when adjust the gap. You are suggested to use 0.028in feeler gauge size if your desired gap is 0.03in, smaller scale than the target gap is recommended
is this common knowledge or do I stick with gap as marked?
MBWorld Fanatic!
Joined: Feb 2017
Posts: 2,319
Likes: 1,217
From: Baltimore County, MD
'13 s212 63 p30. '06 LX470
I am about to gap my plugs and I read this on the gapping tool’s instructions
is this common knowledge or do I stick with gap as marked?
- Adjustment Tips: For normal physical phenomena, some spark plugs electrode will spring back when adjust the gap. You are suggested to use 0.028in feeler gauge size if your desired gap is 0.03in, smaller scale than the target gap is recommended
is this common knowledge or do I stick with gap as marked?
MBWorld Fanatic!
Joined: Feb 2017
Posts: 2,319
Likes: 1,217
From: Baltimore County, MD
'13 s212 63 p30. '06 LX470
Bulletin are often because they realize the factory may not have done something right and when going back in to make sure they are done right. It would follow that they saw issues in engines during a warranty period and this indexing helps ensure the best even atomization. Its obviously a bad design if the tolerances are that tight but the manufacturers of the plugs cant meet spec.
Out Of Control!!
Joined: Apr 2019
Posts: 12,003
Likes: 6,827
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
RELIABLE IGNITION SPARKS
I think the key is to realize which way the gap goes and what do we want and what we should do.
Gap doesn't spring back open right away, it takes countless heat cycles for steel to exert its shape memory.
What we want is a consistent spark rather than a long spark once a while.
So what you want is to under gap a hair knowing in 10kMi your plugs gap will have slightly widen into spec instead of out of spec already.
Make sure you do not drop any plug to the floor while gapping. If a plug falls down, don't use it! Work on your plugs over a table prior to installing.
Gap doesn't spring back open right away, it takes countless heat cycles for steel to exert its shape memory.
What we want is a consistent spark rather than a long spark once a while.
So what you want is to under gap a hair knowing in 10kMi your plugs gap will have slightly widen into spec instead of out of spec already.
Make sure you do not drop any plug to the floor while gapping. If a plug falls down, don't use it! Work on your plugs over a table prior to installing.
Member
Joined: Sep 2008
Posts: 92
Likes: 41
From: Rocklin, CA
'14 CLS550 , '86 420SEL
thank you all for the tips, I successfully swapped out plugs, ignition coils and boots. I have never pulled so hard to remove the coils in my life; the job took way longer than expected.
Out Of Control!!
Joined: Apr 2019
Posts: 12,003
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
tough boots
You won't have to revisit for another 50kMi or so. Hopefully the coils and boots will get the benefit of normal engine heat level.
Having a trusted ignition is a solid base for engine performance.
Last edited by CaliBenzDriver; Mar 3, 2025 at 04:26 PM.
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Member
Joined: Sep 2008
Posts: 92
Likes: 41
From: Rocklin, CA
'14 CLS550 , '86 420SEL
there's a trick... unplug the boots from the coils first then it's easy to remove else it is pulling a high vacuum and quite difficult.
You won't have to revisit for another 50kMi or so. Hopefully the coils and boots will get the benefit of normal engine heat level.
You won't have to revisit for another 50kMi or so. Hopefully the coils and boots will get the benefit of normal engine heat level.
MBWorld Fanatic!
Joined: Feb 2017
Posts: 2,319
Likes: 1,217
From: Baltimore County, MD
'13 s212 63 p30. '06 LX470
Hopefully you used a bit of dielectric grease or silicone to prevent the hard pulling in the future. In the worry of breaking the wires of the coils, they are replaceable if need be. Glad you got it all done and now know how to save that install money going forward.
Member
Joined: Sep 2008
Posts: 92
Likes: 41
From: Rocklin, CA
'14 CLS550 , '86 420SEL
Yes! there was a tiny bit of some sort of grease from the factory on the new boots, but I added a little dielectric grease out of habit. Surprisingly, I only broke 1 out of 8 of the original boots.
Senior Member
Joined: Mar 2018
Posts: 494
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From: KY
2015 E63S Sedan, 2014 E550 Coupe, 2013 E350 Wagon
Another couple tips for the future…coil boots are much easier to pull out when warm. If situation allows, do work as engine cooling down (not while piping hot of course). Also, I take a scrap piece of insulated wire (think speaker cable or similar) and shape into a 10” long loop. You can hook that around the point on back of coil boot to pull with
Member
Joined: Sep 2008
Posts: 92
Likes: 41
From: Rocklin, CA
'14 CLS550 , '86 420SEL
Another couple tips for the future…coil boots are much easier to pull out when warm. If situation allows, do work as engine cooling down (not while piping hot of course). Also, I take a scrap piece of insulated wire (think speaker cable or similar) and shape into a 10” long loop. You can hook that around the point on back of coil boot to pull with
Out Of Control!!
Joined: Apr 2019
Posts: 12,003
Likes: 6,827
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
multiple shades of grey
Combustion "misfires" have many causes from lean mixtures, to bad sparks and poor timings.
-- Small lean misfire are laggy weaknesses
-- Heavy ones are complete stumbles with injector off.
-- And every strength in between!
"No fault code" is still ****-poor performance.
You best be far away from the misfire territories.
>> HERE IS HOW TO GET THERE:
-- Step No 1: ALL reliable ignition components.
-- Then you get good TIMINGS (MOD-4)
-- Then ECU rewards you with good MIXTURES
-- Then you have strong CONTRIBUTIONS.
= Great Mercedes ownership: nice & easy!
-- Small lean misfire are laggy weaknesses
-- Heavy ones are complete stumbles with injector off.
-- And every strength in between!
"No fault code" is still ****-poor performance.
You best be far away from the misfire territories.
>> HERE IS HOW TO GET THERE:
-- Step No 1: ALL reliable ignition components.
-- Then you get good TIMINGS (MOD-4)
-- Then ECU rewards you with good MIXTURES
-- Then you have strong CONTRIBUTIONS.
= Great Mercedes ownership: nice & easy!
Last edited by CaliBenzDriver; Mar 6, 2025 at 08:07 PM.
