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1998 Ml320 W163 722.6
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Discussion Starter #1
Hello everyone, this is my first post but this forum has helped me a lot in the past few years. I have a 98 ml320 with 260k miles on it! She has been a great car with no major issues in 6 years. Recently my wife went to the store about 2 miles away. When she came home she said the car wouldn't shift past 2nd gear and had little to no power. A few days later i went to start it up to put it in the garage to do a transmission service, oil change and new spark plugs since those were a few years old. When i tried to start, it spettered and turned for 30ish seconds but didn't start. Tried again and it started but idled really rough. After about a min the idle settled but when i put it in gear it got realy rough again. Also if i give any throttle it cuts out then revs when i release. I had read that it might be the Cats so i temporarily removed them but this didn't help. I put the code reader on it and got the following codes

P0410
P0304
P0305
P0306
P0300
P0161
P0170
P0173

Any help would be appreciated, i have plenty of time to tinker but limited funds as its my off season. Just need her to last another 6-9 months untill i can get a new car.
 

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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Basics? Fuel pressure?
 
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CURRENT: 2011 SL550 FORMER: C300, ML350, CLK550 Cabriolet, C240, ML320, 300TD
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P0410 is an issue with the air pump, which should not cause any adverse performance issues.
P0300 is "misfiring" and the last digit of the other P03xx codes indicate the specific cylinder.
P0161 is related to the O2 sensors "downstream" of the cats. This generic OBDII codes represents one of four different MBZ-specific DTCs, so I can't say what the problem would be, but my best guess is "P2089 - [8] Heating of component G3/5 (Left O2 sensor, after TWC [KAT]) : Heating capacity is too low. (P0161)" which can occur with misfires.
P0170 and P171 don't directly translate to specific DTCs for your car, but they indicate general issues with fuel trim.

I doubt that the three plugs, wires or coils on cylinders 4, 5 and 6 all went out at the same time. These are all on the left engine bank, so there seems to be an issue only on that side. Just a wild guess, but it could be a clogged cat or muffler on that side especially if they are original parts with 260K miles.
 
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Registered
1998 Ml320 W163 722.6
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Discussion Starter #5
P0410 is an issue with the air pump, which should not cause any adverse performance issues.
P0300 is "misfiring" and the last digit of the other P03xx codes indicate the specific cylinder.
P0161 is related to the O2 sensors "downstream" of the cats. This generic OBDII codes represents one of four different MBZ-specific DTCs, so I can't say what the problem would be, but my best guess is "P2089 - [8] Heating of component G3/5 (Left O2 sensor, after TWC [KAT]) : Heating capacity is too low. (P0161)" which can occur with misfires.
P0170 and P171 don't directly translate to specific DTCs for your car, but they indicate general issues with fuel trim.

I doubt that the three plugs, wires or coils on cylinders 4, 5 and 6 all went out at the same time. These are all on the left engine bank, so there seems to be an issue only on that side. Just a wild guess, but it could be a clogged cat or muffler on that side especially if they are original parts with 260K miles.
I took the cats out of the equation temporarily, didnt seem to help. Just so im clear left bank means passenger side facing the car correct?
 

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W163 and General M Gremlin
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I dont have a fuel pressure tester.. is there a way to check without it?
Welcome to BW FoolwithWrench,

Good to have you as a new member.
To realize the full benefit of this forum, please complete your user CP profile
====>
click on your icon----> click on Account Settings---->
goto Account Details----> add vehicle details---->
ADD your make model YEAR ----> click save.

Borrow one from your local parts store. Folks south of the 49th have the luxury of having this option available.

Also, another note, since you own a scanner/code reader, and it looks like you wish to DIY, so you'll need to own a few other tools to give your ML some TLC (which it sounds like you have already...)
The age of these w163s, are going to need them. Worth the small investment if you plan on keeping this suv.
 
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I took the cats out of the equation temporarily, didnt seem to help. Just so im clear left bank means passenger side facing the car correct?
So you removed the exhaust? Did you clear the errors and then run and rescan? Other thoughts: Any signs of rodent infestation and chewed wires? How about water in the e-Box?

Left bank = USA Driver's side, so standing in front of the car looking back at the engine, it would be on your right.
 
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I dont have a fuel pressure tester.. is there a way to check without it?
I think the fuel rail test valve is the same as the low-side of an R134-A refrigerant system. You may be able to use an AC gauge to test pressure. Just be careful working around fumes!
 
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1998 Ml320 W163 722.6
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Discussion Starter #9
So you removed the exhaust? Did you clear the errors and then run and rescan? Other thoughts: Any signs of rodent infestation and chewed wires? How about water in the e-Box?

Left bank = USA Driver's side, so standing in front of the car looking back at the engine, it would be on your right.
Yes i removed the exhaust but i guess on the wrong side lol. I will go try the other side. And no i hadn't wied the codes yet but i will do that. No sign of rodents.
 

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W163 and General M Gremlin
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Yes i removed the exhaust but i guess on the wrong side lol. I will go try the other side. And no i hadn't wied the codes yet but i will do that. No sign of rodents.
Before you decide to remove the other side, why not test using a temp gun fore and aft. Save you more time and effort.
btw, you can borrow this tool too.
 

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'95 S500 (sold), '97 E420 '99 ML320
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#1 fix the cause of the 3xxx codes. (You may well fix some of the others in doing so) The 161 code is most likely a result of the 300 codes
#2 How are the cylinders numbered? Are #s 4,5 and 6, on the same bank? (like a ford) If so, that's the cat you need to disconnect. Either way, that's the first thing to correct. The misfire, will cause other codes, especially O2 codes.
#3 Has the engine bay been washed recently? I've run into misfire problems due to excess moisture after washing. (on my E420 but that's a whole 'nother critter)
 

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#2 How are the cylinders numbered? Are #s 4,5 and 6, on the same bank? (like a ford) If so, that's the cat you need to disconnect.
1-2-3 are on the right bank (USA passenger side), 4-5-6 are on the left bank (USA driver's side. Cylinders 1 and 4 are on the front, cylinders 3 and 6 are the rearmost.
 

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1998 Ml320 W163 722.6
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Discussion Starter #13
Update! I loosened the exhaust (on the correct side this time 🙄) and she is up and running again! Now i need to find the clog. Assuming its the cats. I wiped the codes and will see if my other issues return. Thanks to all for your responses and advice.
 

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I would replace the catalytic converts, resonators and mufflers. Often, the cats disintegrate and molten metal is thrown down the exhaust pipe and lodges in the resonators or mufflers.
 
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