2001 mercedes c320 3.2l stalling accompanied with no comm w/ecm

Hi again, I bought a broke M-B for my fiance.

Symptom: Vehicle starts and runs fine for the first 15 minutes, then the vehicle simply stalls right out. can re-start the vehicle almost immediately afterwards and it will run for about another five minutes and stall. The vehicle will start almost right back up. The stalling gets more frequent and the length of time that you have to wait for the vehicle to re-start lengthens and it is a no crank no start during the usually short length of time you must wait for it to re-start. also the fan spins full speed while waiting for it to be able to crank again.

History of the car is, the previous owner had it at the benz dealer for this stalling problem and they told him it needed an ECM. So the customer took the ecm out himself and sent it out to some aftermarket place to have it "re-furbished" and that did not fix it

tests completed so far: connected verus pro 17.2 scan tool. found multiple u codes and low voltage codes in all modules. cleared everything. monitored data in all ecu`s during stall event. found that ONLY the ECM loses "comm" during stall event. found u codes re-appearing in abs and ipc which appear to be on the same data bus as the ecm. i`v monitored both power feeds to the ecm with labscope during stall event. monitored all four ground wires to ecm during stall event and all = OK. Iv actually checked these more than once... Iv monitored can hi and lo at the ecm during the stall event and these are ok. Iv monitored the 5 volt ref wire and the sensor gnd wire at the ecm and i never lose either of them during the stall and "no comm" event. only dtc in the ecm is p0155 for downstream o2 heater ckt which i checked at the ecm and found 0 volts and connected a amp clamp around the wire and found o amps leading me to believe there is actually an open in the circuit and not causing my stall event. The o2 ckt is ground side switched i confirmed it with a diagram. also this dtc does briefly go away after each time it stalls further confirming the ecm no comm issue.. along with the full speed rad. fan and the "lost communication" message i get on my scanner while viewing data right when it stalls.

The Ecm for this vehicle is very expensive. M-B will not program a used ecm from what im told. so far i havent found anyone with MB re-flash capabilities in my area. I have a friend with an autel scanner that claims to have a ecm programming "function" ( not autel`s pass-thru simply a programming "function" ) so im not sure it will work. All I can find from a google search are companies wanting me to send them my ecm so they can re-furbish it but i do not believe that the issue within this ecm is repairable. I think these places more repair injector and coil drivers and things like that... I would spend the money for a OE ecm but I really want to be 100% before I do so any input is appreciated.

<update> - symptom persists with maf unplugged - symptom persists with cam sensor unplugged - symptom with map sensor unplugged scoped inj. current vs cyl. 1 ignition primary ckt and found that both inj. pulse and ignition cut out @ exactly the same time. - also scoped injector currents and ign. coil currents and found them all to be identical , none appear to be shorted based on waveforms. I just ordered a used ecm from ebay. I pulled mine apart and cant find any obvious faults in it. I watched a few youtube videos and I do believe I`ll be able to program the used ecm to my car with my friends autel ms906##. Ill post an update on how it all goes. hopefully it will be fixed

i could really use a suggestion. just checked alternator ripple and it seems ok... during the stall event i never lose any signals.. 5 volt ref... can hi and lo never drop out... sensor grounds all look good during stall event..... im not convinced this re-built ecu is bad yet...

<update> I took the ecm apart with all of the connectors still plugged in and the car seemed to run much longer. still would stall though so I got a hair dryer and started blowing on it and within about 15 seconds it stalled and the "no comm" lasted for about 30 seconds with the fan blowing high speed. I let it cool down for a while and with the key on engine off blew on the ecm with a hair dryer moving it around for about 20-30 seconds and then the fan started blowing high speed with "no comm". I believe this test proves the ecm is bad. I ordered a used one and am crossing my fingers autel scan tool can clone my existing one to the used ecm...

Good work sorting through that one!
Sorry you didn't get any replies between yesterday and today, but it looks like you found the problem.
Let us know how you make out with the used PCM and the Autel.

<update> In case anyone is following this thread... I got the used pcm in the mail the other day. Found out that the Autel cannot perform the programming or scn coding without the j2534 pass-thru device. I did however stumble across a youtube video showing how to transfer the eeprom chip on this particular ecm here is the link -- So i took the two computers to a local electronic repair company (electronic repair company is literally the name of the place) here in Phoenix and showed them the chip that i needed swapped. They charged me forty dollars. Called me the next day said it was done. I installed the used ecm into my mercedes and voila. It started right up , scanned for codes and there are none present in ANY module. no vin mis-match , immobilizer codes etc. etc. I let the car run for two hours to verify the repair. Putting new tires on it tomorrow getting it insured and a 30-day temporary tag so I can get it through emissions. Looks like the Dealerships original call on the ecm was a good call and the customer got ..... $600.00 by wherever he sent the ecm to get "re-furbished" . . . I was hoping for a power or ground issue when I bought it :unsure:

Please check your private messages by clicking on your Avatar or user name.