MB ML 400CDI runs uneven and dies when hot
Thread Starter
Newbie
Joined: Dec 2018
Posts: 13
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From: NORRKÖPING Sweden
Mercedes ML400CDI AMG
MB ML 400CDI runs uneven and dies when hot
Hi all.
Happy new year.
I hope you can help me out with this matter.
I have a MB ML 400CDI V8 year 2004 with about 220000km or 130000miles. It is a diesel and it runs uneven when warm.
When the engine is cold, it starts and runs perfect. After about 15-20 min driving, when slowing down and when the RPM goes from cruise RPM to idle, it usually dies. It also responds poor on low RPM from time to time when warm.. Then it won’t start for the next two or three attempts 1-2 min of trying to start it. Then it usually starts OK and runs without problems for the next 15-20 min. At idle, when normal working temp has been reached, it runs uneven, or more like revving up and revving down for short and quick intervals, then it revvs from about normal idle 700RPM to 1000RPM to about 400RPM a few times before dying. Usually the parking sensor system comes and goes on and off a few times just before totally shutting down. On top of that, I have noticed a distinct smell of diese smokel in the cabin when standing still at idle. The smell goes away as soon as some speed is achieved, like 10-20 km/h 10 mph. Maybe someone knows something about these problems?
Happy new year.
I hope you can help me out with this matter.
I have a MB ML 400CDI V8 year 2004 with about 220000km or 130000miles. It is a diesel and it runs uneven when warm.
When the engine is cold, it starts and runs perfect. After about 15-20 min driving, when slowing down and when the RPM goes from cruise RPM to idle, it usually dies. It also responds poor on low RPM from time to time when warm.. Then it won’t start for the next two or three attempts 1-2 min of trying to start it. Then it usually starts OK and runs without problems for the next 15-20 min. At idle, when normal working temp has been reached, it runs uneven, or more like revving up and revving down for short and quick intervals, then it revvs from about normal idle 700RPM to 1000RPM to about 400RPM a few times before dying. Usually the parking sensor system comes and goes on and off a few times just before totally shutting down. On top of that, I have noticed a distinct smell of diese smokel in the cabin when standing still at idle. The smell goes away as soon as some speed is achieved, like 10-20 km/h 10 mph. Maybe someone knows something about these problems?
MBWorld Fanatic!
Joined: Nov 2015
Posts: 1,456
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From: Westcoast/Interior
02w163ML500 / 97w210E50AMG / 99w202C230k / 95w124500e-wip
calle123,
Welcome.
Have you done a scan to see what saved codes you have?
Need to scan and post some codes.
Could be a faulty MAF, but it's hard to diagnose with general symptoms described.
Also, check your thermostat.
Welcome.
Have you done a scan to see what saved codes you have?
Need to scan and post some codes.
Could be a faulty MAF, but it's hard to diagnose with general symptoms described.
Also, check your thermostat.
Thread Starter
Newbie
Joined: Dec 2018
Posts: 13
Likes: 0
From: NORRKÖPING Sweden
Mercedes ML400CDI AMG
Hi. Thanks for the reply.
The workshop has done some troubleshooting and found that a frew injectors are overcompensating. They wanted to change the all eight to a cost of 50.000kr/ USD 5500. Can I Scan the codes myself? What equipment do I need for that? What is a MAF?
The workshop has done some troubleshooting and found that a frew injectors are overcompensating. They wanted to change the all eight to a cost of 50.000kr/ USD 5500. Can I Scan the codes myself? What equipment do I need for that? What is a MAF?
MBWorld Fanatic!
Joined: Nov 2015
Posts: 1,456
Likes: 140
From: Westcoast/Interior
02w163ML500 / 97w210E50AMG / 99w202C230k / 95w124500e-wip
Hi. Thanks for the reply.
The workshop has done some troubleshooting and found that a frew injectors are overcompensating. They wanted to change the all eight to a cost of 50.000kr/ USD 5500. Can I Scan the codes myself? What equipment do I need for that? What is a MAF?
The workshop has done some troubleshooting and found that a frew injectors are overcompensating. They wanted to change the all eight to a cost of 50.000kr/ USD 5500. Can I Scan the codes myself? What equipment do I need for that? What is a MAF?
What saved codes or details did they provide you to verify this?
I would also obtain a second opinion from another shop too and have them show you the codes they scan.
Yes, you can scan the codes yourself with a scanner you can purchase.
I believe yours is a 2004 ML model? It's a W163 first gen MB SUV.
Do a search here on this forum and here for recommended scanner you can use.
MAF = mass (air) flow sensor
I would also first recommend cleaning your your MAF with CRC MAF cleaner. It's very cheap to DIY.
Again, use the search button or search the internet of how-to clean MAF on W163 ML. Very simple procedure.
Thread Starter
Newbie
Joined: Dec 2018
Posts: 13
Likes: 0
From: NORRKÖPING Sweden
Mercedes ML400CDI AMG
That’s what I told the workshop as well. I bought this OBD 2 WiFi tool that I connected to the car yesterday. I could only find one error code P2003, Diesel particle filter below limit value but that fault code popped up as last known fault code. However when I looked at the actual diagram parameters I could see that the generator voltage was fluctuating when the car was on idle. It fluctuated from 11.3V to 13.1V. The car suddenly died again after 30 min drive when the RPM came down from 2000RPM to idle with subsequent poor throttle response. I have not checked the MAF yet but will do that ASAP.
Thread Starter
Newbie
Joined: Dec 2018
Posts: 13
Likes: 0
From: NORRKÖPING Sweden
Mercedes ML400CDI AMG
I have cleaned the MAFs with CRC today and I could notice some difference. When the engine has reached working temp of 85C it seems to run fine with a stable idle RPM. I had one sudden engine stop during the first 5 min drive. The engine was cold and I stopped at an intersection when the engine suddenly died (when the RPM came down from cruise 2000RPM to idle)
