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Hey guys new to the forums and just thought first off I would say hello. Next, I purchased a 2000 ML 320 through an auto auction (My father is owns a used car dealership). Well, the vehicle originally wouldn't shift out of first gear, took it to the local MB dealership and they serviced the transmission, now it shifts fine. Next problem we have encoutered is that it has some rattle coming from the engine area, although I do not believe it is internal as it is intermittent and the engine is perfectly quite when you rev it. This rattle generally occurs when there is a slight load placed on the engine i.e. initially when you put the vehicle in reverse or drive from park or nuetral, or when you turn the streeing wheel all the way to the left or right and the power steering pump puts a slight load on the engine. Next and final problem is the vehicle keeps throwing a code, which in turn causes the vehicle to freak out and miss on several cylinders (Have an OBDII scanner, always the same codes). The vehicle will run fine for a while and then the check engine light will flash a couple times and then stay on and the vehicle immediately develops a horrible misfire( like it's running on 3-4 cylinders). If you turn the car off and restart it the misfire will go away, but the MIL light stays on. Then it will randomly start the crazy misfire again at another random time. This happens even if you clear the codes . The codes it is showing are: Cyl. #2 misfire, Cyl. #4 misfire, and Random Multiple Cyl. Misfire (Once it showed Cyl. #1 misfire, but generally it is only 2 and 4). I will be putting the vehicle on the lift tonight and just wanted to know if anyone has any idea as to where to look. I read about the harmonic ballancer (figure that might be the rattle), so I plan to check that out. We already changed the plugs in the vehicle, so I know they are good. Does anyone know how MB senses a misfire??? I mean does it use the knock sensor??? If that is the case it may be picking up a misfire due to the rattle I am talking about. Once again, the car does not miss at all until the MIL light comes on, only after that. Any help would be greatly appreciated, as we already took it to the local Dealership and they said it was fixed (all that was done, was the codes cleared). Thanks in advance, Drew
 

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ML320/C320 Sprt
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Congratulation on your purchase and welcome on board[:)]

I have the same year as yours and I don't have that kind a problem ( knock on wood[:D]) anyway, how many miles do you have on yours, it might need a tune up or change of spark plug, and what kind a gas are you using is it premium or what. Someone or maybe DRew can add something about your problem.
 

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99ML320 (retired) C230 530xi 911-C4
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65vette396 - 3/8/2005 2:55 PM

Hey guys new to the forums and just thought first off I would say hello. Next, I purchased a 2000 ML 320 through an auto auction (My father is owns a used car dealership). Well, the vehicle originally wouldn't shift out of first gear, took it to the local MB dealership and they serviced the transmission, now it shifts fine. Next problem we have encoutered is that it has some rattle coming from the engine area, although I do not believe it is internal as it is intermittent and the engine is perfectly quite when you rev it. This rattle generally occurs when there is a slight load placed on the engine i.e. initially when you put the vehicle in reverse or drive from park or nuetral, or when you turn the streeing wheel all the way to the left or right and the power steering pump puts a slight load on the engine. Next and final problem is the vehicle keeps throwing a code, which in turn causes the vehicle to freak out and miss on several cylinders (Have an OBDII scanner, always the same codes). The vehicle will run fine for a while and then the check engine light will flash a couple times and then stay on and the vehicle immediately develops a horrible misfire( like it's running on 3-4 cylinders). If you turn the car off and restart it the misfire will go away, but the MIL light stays on. Then it will randomly start the crazy misfire again at another random time. This happens even if you clear the codes . The codes it is showing are: Cyl. #2 misfire, Cyl. #4 misfire, and Random Multiple Cyl. Misfire (Once it showed Cyl. #1 misfire, but generally it is only 2 and 4). I will be putting the vehicle on the lift tonight and just wanted to know if anyone has any idea as to where to look. I read about the harmonic ballancer (figure that might be the rattle), so I plan to check that out. We already changed the plugs in the vehicle, so I know they are good. Does anyone know how MB senses a misfire??? I mean does it use the knock sensor??? If that is the case it may be picking up a misfire due to the rattle I am talking about. Once again, the car does not miss at all until the MIL light comes on, only after that. Any help would be greatly appreciated, as we already took it to the local Dealership and they said it was fixed (all that was done, was the codes cleared). Thanks in advance, Drew
2 Things to check:

* CRANK SHAFT POSITION SENSOR ($70 part)
* SPARK PLUG WIRES (kinda expensive)
* (ok 3 things) EGR valve
 

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Discussion Starter #4
First, thanks JimB and roadsession for your replys. Jim the car has 103,000 miles on it. It has the owners manual and all of the service records appear to be current. We Changed the plugs first thing to rule that out. The car has had premium put in it from two different gas stations to rule that out.

Roadsession, How would one rule out the crank position sensor? do you know what they are supposed to read if they are good? Plug wires look good, but I haven't ohmed them out just yet. Do you know what kind of Ohm reading they are supposed to read? I will check the egr valve as well. Thanks again for the reply's and please keep them coming, Drew
 

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BenzWorld Post Whore
10 E350 4MATIC
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4th thing to check...MAF sensor; 5th thing to check...02 sensor
 

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Discussion Starter #6
S4toML, thanks for the reply as well. Is MB really that vague in thier codes that the Mass air meter or O2 sensor could cause it to show a misfire on two specific cylinders?? I'm just asking, because a GM or any other american vehicle for that fact would show the mass air meter or O2 sensor failure in the same case. Thanks again, Drew
 

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Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
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Is MB really that vague in thier codes that the Mass air meter or O2 sensor could cause it to show a misfire on two specific cylinders?? I'm just asking, because a GM or any other american vehicle for that fact would show the mass air meter or O2 sensor failure in the same case.
Keep in mind that all the ECM does is take input from all the various sensors and calculate the optimal fuel and air mixture given those current conditions. Most sensors do not have any sort of diagnostic circuit that would tell the ECM when they are bad. Instead, the ECM registers a fault code when the value returned by a sensor is outside of the expected range given the readings from all other sensors.

The fault codes do not necessarily indicate that the part giving the erroneous reading is itself faulty. For example, O2 sensors tell the ECM the results of the burn of the mixture. A very rich mixture could cause the O2 sensor to give a reading that is “out of bounds�. The resulting fault code would likely indicate a “problem� with the O2 sensor. The sensor itself may be perfectly good, but something upstream failed and caused the rich mixture. This type of anomaly is true for all vehicles, not just MBZ. A mechanic that replaces a part just because it registered a fault is not a mechanic; he is a “parts swapper�.

- RODNEY
 

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Discussion Starter #9
Guys, thanks for all of your help and the warm welcome onto the board. I put the vehicle on the lift last night and realized why you guys call the dealerships, "STEALERSHIPS". They worked on th car three times for the problems I told you guys about and never fixed the vehicle. I put the car on the lift last night and determined the problem in about 15 minutes. All of the flexplate bolts that hold the torque converter to the flexplate had come loose, some to the extent that they were rubbing the bad of the oil pan/block [:0]. Broke out some locktight, torqued them to spec., popped the inspection plugs back in, and it drives like a dream. [8D] Thanks again, and I look forward to being part of the MB community, Drew
 
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