2007 E550 Spark plugs
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Joined: Jan 2016
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From: Rochester NY
07 E550 4M - 11 Audi TT - 99 Expedition EB
2007 E550 Spark plugs
I've seen a bunch of other threads on this but nothing concrete for the e550.
I was having some issues with a sulfur smell from the exhaust on hard acceleration. I noticed my fuel trims were consistently -3 to -5 or so and that is with 10% ethanol fuel, which should yield +4% or so fuel trims assuming all else is well, so the trims indicated a rich condition.
I've replaced most things related to air fuel and finally got around to doing the spark plugs this week. There was a set of Autolite Iridiums installed by the previous owner. I ordered Bosch YR7MPP33 as all the sites I checked specified these for my car. After a few minutes of driving around, fuel trims did move to +3% which is about what I was hoping for. I also noticed a significant decrease in the sulfur smell thought it wasn't completely gone. I figured this was all set, but while thumbing through my owners manual today I came across a page for spark plugs.
The Y(R)7MPP33 are shown as being for the 350 and having a gap of 0.8mm. It shows that I should have used Bosch F8DPP332U with a gap of 1.0mm. These don't seem to be available anymore, though I saw some reference to Bosch 7422 possibly replacing them. Nothing anywhere seems to indicate the Bosch 7422 are for the E550 though.
Does anyone know if they re-specified the F8DPP332U with the YR7MPP33s? The fact that I'm still getting a mild sulfur smell makes me thing maybe there is not enough spark to get a complete burn on the fuel, either due to the part being wrong or the gap being smaller.
Hoping someone has some solid info on what plugs should be in this car. The manual also shows a set of NGK, though I prefer Bosch for German cars and NGK for Japanese.
I was having some issues with a sulfur smell from the exhaust on hard acceleration. I noticed my fuel trims were consistently -3 to -5 or so and that is with 10% ethanol fuel, which should yield +4% or so fuel trims assuming all else is well, so the trims indicated a rich condition.
I've replaced most things related to air fuel and finally got around to doing the spark plugs this week. There was a set of Autolite Iridiums installed by the previous owner. I ordered Bosch YR7MPP33 as all the sites I checked specified these for my car. After a few minutes of driving around, fuel trims did move to +3% which is about what I was hoping for. I also noticed a significant decrease in the sulfur smell thought it wasn't completely gone. I figured this was all set, but while thumbing through my owners manual today I came across a page for spark plugs.
The Y(R)7MPP33 are shown as being for the 350 and having a gap of 0.8mm. It shows that I should have used Bosch F8DPP332U with a gap of 1.0mm. These don't seem to be available anymore, though I saw some reference to Bosch 7422 possibly replacing them. Nothing anywhere seems to indicate the Bosch 7422 are for the E550 though.
Does anyone know if they re-specified the F8DPP332U with the YR7MPP33s? The fact that I'm still getting a mild sulfur smell makes me thing maybe there is not enough spark to get a complete burn on the fuel, either due to the part being wrong or the gap being smaller.
Hoping someone has some solid info on what plugs should be in this car. The manual also shows a set of NGK, though I prefer Bosch for German cars and NGK for Japanese.
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Joined: Jan 2016
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From: Rochester NY
07 E550 4M - 11 Audi TT - 99 Expedition EB
I probably will if I can't get a definitive answer on the correct plugs. Further digging on most parts sites show the plugs I used are correct. The only thing that says they're not is my manual.
The NGK plugs the manual lists are available. I may go that route or just end up re-gapping. Still hoping someone knows for sure which Bosch plugs the m273 likes.
The NGK plugs the manual lists are available. I may go that route or just end up re-gapping. Still hoping someone knows for sure which Bosch plugs the m273 likes.
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From: dmv
2009 E550 2000 Honda civic mash n' go
I probably will if I can't get a definitive answer on the correct plugs. Further digging on most parts sites show the plugs I used are correct. The only thing that says they're not is my manual.
The NGK plugs the manual lists are available. I may go that route or just end up re-gapping. Still hoping someone knows for sure which Bosch plugs the m273 likes.
The NGK plugs the manual lists are available. I may go that route or just end up re-gapping. Still hoping someone knows for sure which Bosch plugs the m273 likes.
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2007 E550 4matic
I don't know about the Bosch choice, but the NGK PFR spark plug for M273 listed in the owner's manual is absolutely incorrect and physically won't even install.
The correct NGK spark plug is either PLKR-6A (hotter plug) or 7A (colder plug). These arrive pre-gapped at 0.032".
The original plugs I removed from my M273 were manufactured by NGK and marked with tiny Mercedes stars, so Mercedes has no issue installing Japanese plugs.
The correct NGK spark plug is either PLKR-6A (hotter plug) or 7A (colder plug). These arrive pre-gapped at 0.032".
The original plugs I removed from my M273 were manufactured by NGK and marked with tiny Mercedes stars, so Mercedes has no issue installing Japanese plugs.
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From: Highlands Ranch, Colorado
2014 BMW M235i
Ran NGK Platinums on my E550 just as ordered from NGK for a few years without any trim or misfire issues that weren't caused by faulty coils, perhaps some sulfur smell did exist, but I don't remember regapping them
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From: Rochester NY
07 E550 4M - 11 Audi TT - 99 Expedition EB
I'm surprised at all the different information on plug type and gap. I ended up re-gapping to 1mm and it either made no difference in the sulfur smell or possible made it a bit worse. Not really what I expected but I will assume the plugs are fine at this point. It made no noticeable difference in the running behavior or trims that I can see so far.
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From: Highlands Ranch, Colorado
2014 BMW M235i
That sulfur-like smell was always present to some extent in my E550, even with factory gapped plugs or NGKs out of box. As you said in your original post, this would be indicative of a rich condition. I wouldn't worry too much about it unless the engine is running poorly, bogging, or misfiring... the latter of which is likely due to bad coils in my experience.
Last edited by AMGAffalterbach; May 1, 2016 at 05:06 PM.
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Joined: Jan 2016
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From: Rochester NY
07 E550 4M - 11 Audi TT - 99 Expedition EB
Thanks for the input, and it is running fine. Trims perhaps indicate a slightly rich condition still exists but I don't think enough to think anything is really wrong with them at this point. I don't think it's normal though and I doubt most Mercedes/auto owners would find a rotten egg smell on hard acceleration to be acceptable. I'm also noticing the catalytic temperatures are reaching 1760 degrees at WOT. That coupled with the smell leads me to believe I'm damaging the cats, so I'm still hoping to find a resolution.
At this point, I may look into removing the injectors for proper cleaning and/or replacing the injectors. I may also consider getting an aftermarket tune in hopes of leaning out the mixture a bit at higher rpms where I'm currently seeing a mixture of about 12.5:1 AFR. The only other thing I can think of is actually replacing the cats which has a steep cost, and if the problem is something else, I could end up ruining the new cats as well.
At this point, I may look into removing the injectors for proper cleaning and/or replacing the injectors. I may also consider getting an aftermarket tune in hopes of leaning out the mixture a bit at higher rpms where I'm currently seeing a mixture of about 12.5:1 AFR. The only other thing I can think of is actually replacing the cats which has a steep cost, and if the problem is something else, I could end up ruining the new cats as well.
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From: dmv
2009 E550 2000 Honda civic mash n' go
I would look into your exhaust system me personally. But that's your car. Usually a sulfur smell is something related to catalyst or bad gas. The gap theory could be possible but you can't be the first person to replace plugs and or have a sulfur smell..
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2014 BMW M235i
^It's related to the catalytic converters because as OP already said, if he's running rich and excess fuel is being burned in the exhaust system, it will heat up the catalytic converters and cause the sulfur smell, which might be due to poor ignition, but is possibly due to other issues with the mixture, injectors, tune, and other such factors that are messing with AFRs. As OP seems to be very technically savvy and understand this, if you replace your catalytic converters without fixing the root of the issue, you'll end up just damaging another set of cats.
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2008 E350 2013 Tahoe 2007 Mustang GT Conv.
