Help! S350L (W221) engine dies/misfires

[SLC]

Hi all, I've been having this problem over the last 1 year. My car's engine would shut down by itself. This happens every few weeks or around 2 to 3 times a month on average. It doesn't shut down when I'm driving (the engine may sputter but it won't die). It only dies when I stop at a traffic junctions or when I stop to reverse. In other words, it dies only when the car is at a very low RPM. Ever since it started happening a year back, my mechanic (not cycle) started changing parts relating to the fuel system. You name it, I've changed it - fuel filters, both low and high pressure fuel pumps, fuel pressure sensors, spark plugs and I even changed the V6 fuel rail! After it dies, sometimes, the CEL will appear and sometimes it won't appear. When I send it in to the workshop (with the CEL appearing), the same diagnostics fault code will appear; "Fault code P008792 (the fuel pressure in the system is too low. The function or the instruction is faulty). When I brought it in to Cycle, they said that it's most likely the fuel pumps. But I now know that it's not the fuel pumps! So I would appreciate it if someone here in this forum is able to point me to the right direction. Thanks!  

[MBENZ]

If your rpm fluctuates and end up too low and then stall, likely your engine ECU is faulty. Very common problem for W221.  A faulty ECU will give you all sorts of component error, pinpointing to the wrong diagnosis by the mechanics.

[kepiting1sg]

On ‎29‎/‎5‎/‎2018 at 2:43 PM, SLC said:

Hi all, I've been having this problem over the last 1 year. My car's engine would shut down by itself. This happens every few weeks or around 2 to 3 times a month on average. It doesn't shut down when I'm driving (the engine may sputter but it won't die). It only dies when I stop at a traffic junctions or when I stop to reverse. In other words, it dies only when the car is at a very low RPM. Ever since it started happening a year back, my mechanic (not cycle) started changing parts relating to the fuel system. You name it, I've changed it - fuel filters, both low and high pressure fuel pumps, fuel pressure sensors, spark plugs and I even changed the V6 fuel rail! After it dies, sometimes, the CEL will appear and sometimes it won't appear. When I send it in to the workshop (with the CEL appearing), the same diagnostics fault code will appear; "Fault code P008792 (the fuel pressure in the system is too low. The function or the instruction is faulty). When I brought it in to Cycle, they said that it's most likely the fuel pumps. But I now know that it's not the fuel pumps! So I would appreciate it if someone here in this forum is able to point me to the right direction. Thanks!  

Go to a workshop that knows their stuff and not maybe this or that.

Visit our site sponsor Optima-Werkz at 551 Upper Thomson Road.

I do my car repairs and servicing there.

Never fails to rectify my car issues (idle cam gears, leaking turbo, faulty gear box pcba, etc) over the years.

BTW all these issues has CEL lighted up.

http://www.sgmerc.com/forum/111-optima-werkz-pte-ltd/