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1999 ML320 and 2009 E350
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98 Posts
Discussion Starter #1
Spark plug question on 1999 Ml320


My ML320 starting to show some engine running rough at idle (no check engine light at least for now). When we scan the code at O'Reilly Auto it shows P0400 code. Before messing with the EGR I thought I will replace the Spark plug, do you think it's worth doing that or get the EGR tube cleaned? My ML has 192000 miles and last spark-plug change was done on 158000 miles.

- Do I need to replace the Spark-plug wires or just replace the Sparkplug?
- Autohausaz.com multiple choices, which one should I use? Anyone recommends Bosch 4501?
 

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ML320 2002
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1,600 Posts
First of all test the spark plug wires. Resistance between the terminals should be 2 kOhm when they are brand new. You may measure a range like 2- 2.3 k Ohm. If you find one wire that is way off the average, replace that individual wire.
 

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1998 ML320
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613 Posts
My 98 had the 400 code with no mil light. I was going to clean it but it wasn't going to be high on my list as here we have no emission checks so it wouldn't effect much for me other than knowing there was a code. I ended up doing what someone had suggested which was take a long drive with it. I went about 250kms each way and when I got back the code had cleared itself. And it hasn't come back.

I wonder if the problem is from around town driving and the engine not being fully warmed up. With an external pipe like the 112/113 has with the bellows or flex joints that would cool off anything passing through and eventually plug.
 

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1999 ML320 and 2009 E350
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98 Posts
Discussion Starter #4
First of all test the spark plug wires. Resistance between the terminals should be 2 kOhm when they are brand new. You may measure a range like 2- 2.3 k Ohm. If you find one wire that is way off the average, replace that individual wire.

Thank you, I have tested all the spark plug wires and they are all within the spec.

Should I use the Bosch 4501 or Bosch 7422 spark plug for the replacement plugs?
 

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02 ML320 06 ML500
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17,104 Posts
When it comes to part #'s Bosch is the most screwed up site there ever was. They no longer have part #7422 in their data base, and additionally they only list 6 plugs needed when it's quite obvious that 12 are needed.

The OE plug that you should use isFR8DPP33+, Iridium single electrode.

M/B also used NGK plugs as Original Equipment, part #1FR5D10, stock #4696, Iridium single electrode.

My choice would be NGK by a landslide.
 

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99 ML430, 00 ML320, 05 E500 4matic Wagon
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22,142 Posts
Thanks for posting that.
I like the NGKs better also. I had to put the 7422s in the E500 due to availability. For the next round on the ML I am going with the NGKs.
NGKs are what came out of the E500. Bosch were in the ML from the factory on mine.
 

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2000 ML 430
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1,588 Posts
Im wondering what is the big risk with multi tip electrodes, some members have ran them and they are fine
 

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02 ML320 06 ML500
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17,104 Posts
Im wondering what is the big risk with multi tip electrodes, some members have ran them and they are fine
Then you do what you feel is best, but at $84 a set it could be a little expensive. And by the way, those multi-electrodes do nothing to improve performance.
 

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Super Moderator
99 ML430, 00 ML320, 05 E500 4matic Wagon
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22,142 Posts
They "think" they are fine.
They are redundant. With the twin spark system in the engines there is a multiple spark situation already.
The second plug fires nanoseconds after the first plug to get a clean burn.

Mercedes put out a DTB many many years ago about not using them in the twin spark engines.
Maybe they were just covering their butts if something went wrong with an ignition part, but I am
not one to deviate from what MB's engineers designate as to what is right or wrong. (except for the ATF changes)
 

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1999 ML320
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126 Posts
They "think" they are fine.
They are redundant. With the twin spark system in the engines there is a multiple spark situation already.
The second plug fires nanoseconds after the first plug to get a clean burn.

Mercedes put out a DTB many many years ago about not using them in the twin spark engines.
Maybe they were just covering their butts if something went wrong with an ignition part, but I am
not one to deviate from what MB's engineers designate as to what is right or wrong. (except for the ATF changes)
Hello Noodles,

I really appreciate this web site. I regularly have a challenge searching for and locating the best thread(s) addressing whatever my current concern is. I've recently been relying on a particular thread regarding misfire and catalytic converters. I wouldn't be surprised if there was another thread that already covered all my questions and issues on this topic.

I just came across this post of yours while searching for spark plug recommendations. I'm a real believer in the engineers that designed these things being far more knowledgeable than myself regarding these vehicles - so I am never inclined to second guess. However, their lifetime ATF has had me baffled for a long time. I have improved failing automatic transmissions back to normal function in other vehicles by just replacing the ATF with Mobil 1 synthetic ATF.

So can you point me to the thread discussing this for our ML's?

Can you give me advice for searching for information - or a thread that covers this?

Thank You!

John Olson
 

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Super Moderator
99 ML430, 00 ML320, 05 E500 4matic Wagon
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22,142 Posts
There really are several threads, but they all boil down to the same thing. Use an ATF that is 134 like the Shell or Fuchs. Always check the pilot bushing(13 pin connector for leaks), get a genuine one if needed, and use a good filter. Also having the MB trans dipstick is really something I consider mandatory.

I would not use the Mobil 1. The Shell is actually less money and in your area finding a distributor should not be hard. There is one in Sparks, Nevada. Not sure how close you are to the state line, but if you are located where I think you are it is about 40-45 miles at the most.

Lubricants for Cars & Trucks - Welcome to Silver State Petroleum - NeedOilNow.com
 

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1999 ML320
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126 Posts
There really are several threads, but they all boil down to the same thing. Use an ATF that is 134 like the Shell or Fuchs. Always check the pilot bushing(13 pin connector for leaks), get a genuine one if needed, and use a good filter. Also having the MB trans dipstick is really something I consider mandatory.

I would not use the Mobil 1. The Shell is actually less money and in your area finding a distributor should not be hard. There is one in Sparks, Nevada. Not sure how close you are to the state line, but if you are located where I think you are it is about 40-45 miles at the most.

Lubricants for Cars & Trucks - Welcome to Silver State Petroleum - NeedOilNow.com
Hello Noodles,

Thanks for your advice. I purchased Mobil 1 from Silver State years ago. I'll need to figure out what 134 is - something from MB?

John
 

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1999 ml320,05 cls 55 amg
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163 Posts
I dont know if you have this around where you live but golden west oil company here in san antonio sells shell atf 134 for 60 bucks and they ship also. SHE:5080660 (shell ATF 134 12 quarts)
 

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'02 ML500. 22A292576
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232 Posts
I am
not one to deviate from what MB's engineers designate as to what is right or wrong. (except for the ATF changes)
:laugh

Hello Noodles,

I really appreciate this web site. I regularly have a challenge searching for and locating the best thread(s) addressing whatever my current concern is.

Can you give me advice for searching for information - or a thread that covers this?

Thank You!

John Olson
There's are a couple of threads on the first page now. In future: "Search This Forum" will help you find W163 info. Sometimes you have to be creative and try 2-3 different keywords. FWIW, EVERY Mercedes vehicle from, like 1997 to 2005 or so used the 722.6XX five speed auto transmission AFAIK, then they added the 722.9XX 7 speed auto. Info re: either of these can be found by searching the general Mercedes forum.

In the US you can buy Shell ATF 134 for about $50-$60 per 6 quarts:

Shell ATF 134 Mercedes Benz Transmission Fluid 236 14 236 12 6 Qt Pack 5080660 | eBay

I just bought cases (12) from my local Shell distributor for $63/ea. Now I know what I'm going to do with the leftovers. :devil
 

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1999 ML320
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126 Posts
:laugh



There's are a couple of threads on the first page now. In future: "Search This Forum" will help you find W163 info. Sometimes you have to be creative and try 2-3 different keywords. FWIW, EVERY Mercedes vehicle from, like 1997 to 2005 or so used the 722.6XX five speed auto transmission AFAIK, then they added the 722.9XX 7 speed auto. Info re: either of these can be found by searching the general Mercedes forum.




I just bought cases (12) from my local Shell distributor for $63/ea. Now I know what I'm going to do with the leftovers. :devil
Hello Dlearl,

Thanks for the admin/search advice. Very Helpful!

John
 
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