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ML320
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303 Posts
Discussion Starter #1
I was getting CPS failure symptoms - once the engine warms up, it'll die (randomly, not always) while moving, you'll have to re-start the engine. NO CEL lights at all. Will not stall if the engine is not warmed up.

The only difference is, once it died, usually I could re-start the engine on the 1st or 2nd try. That would not be consistent with CPS failure in that it would take 15 minutes of "cooling down" period before the engine can be re-started.

I decided to replace the CPS as a start but problem did not go away.

Finally hooked up a scanner and saw a fault in the MAF (but no CEL was triggered, just a fault code).

Replaced the MAF and all is well.
 

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02 ML320 06 ML500
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17,105 Posts
Thank you for posting this information. There are so many members who believe that there are no codes set for the MAF and Crank Pos. Sensor.
 

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2001 ML320
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276 Posts
When it keeps doing it, check the fuel pump. Mine had the exact same symptoms. Changed CPS ($300), MAF ($300), Fuel Filter ($300) and finally fuel pump which I have not yet paid for. Vehicle now runs fine.
 

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ML320
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Discussion Starter #4
When it keeps doing it, check the fuel pump. Mine had the exact same symptoms. Changed CPS ($300), MAF ($300), Fuel Filter ($300) and finally fuel pump which I have not yet paid for. Vehicle now runs fine.
That would be my next step (to check the fuel delivery system).

However, I had a semi-working MAF from an S-Class (the MAF "insert" is the same on the S-Class but the housing has a bigger inner-diameter for more air flow so I just swap the MAF insert), installed it and the problem went away. Once I put my old MAF back, problem came right back.

It's been over a month now since I put a new MAF in and no more problems so I'm pretty certain the old MAF was causing all the strange engine stalling problems and not the CPS as I originally thought.
 
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