E350 Mise-Fire Woes
02-27-2024, 07:42 PM
#26
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MY'14 W212 M276 3.5NA @60kMi
PROCESS OF ELIMINATION...
You don't really want to replace parts without knowing what's the car is doing. Ask the computers with your scanner.
Now proceed to some TESTING by eliminations:
Finish your compression testing to have definite hard answer to know if all your cylinders seal or one has mechanical damages?
🤞
Now proceed to some TESTING by eliminations:
- Read pressure data from Low pressure fuel pump
- Read rail pressure of high pressure fuel pump
- Read LTFT: Rich/Lean?
Finish your compression testing to have definite hard answer to know if all your cylinders seal or one has mechanical damages?
🤞
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02-28-2024, 07:37 AM
#27
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2008 E350 (W211 @170K), 2012 ML350 (W166 @119K), 2014 E350 Sport (W212 @96K), 2015 ML350 (W166 @92K)
It would be great if you could separate the low compression issue into:
1 - Poor valve sealing --> Head job ONLY
2 - Poor ring sealing or cylinder scoring --> Likely a whole engine repair
Because (1) is still a reasonable job, it worth doing:
1 - Visual check to see the cylinder w/o opening the head --> Boroscope
2 - Leak down test to determine where the pressure is going to: crankcase (poor ring/cylinder sealing) or intake manifold (poor valve sealing)
3 - I think the compression test is needed ONLY to confirm there is low compression, but it does not tell us what may be wrong.
1 - Poor valve sealing --> Head job ONLY
2 - Poor ring sealing or cylinder scoring --> Likely a whole engine repair
Because (1) is still a reasonable job, it worth doing:
1 - Visual check to see the cylinder w/o opening the head --> Boroscope
2 - Leak down test to determine where the pressure is going to: crankcase (poor ring/cylinder sealing) or intake manifold (poor valve sealing)
3 - I think the compression test is needed ONLY to confirm there is low compression, but it does not tell us what may be wrong.
The following 2 users liked this post by juanmor40:
CaliBenzDriver (02-29-2024),
TheBenzIsOne (02-29-2024)
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