M104 shuts down when hot
 

my 60k mls 1994 320 coupe automatic tranny starts fine when cold. but when restarting with engine still hot i experience the following condition: engine starts up normal. i put the tranny into D or R still normal. but when i try to get out of a parking lot and step on the accelerator only briefly followed by breaking, the engine stumbles and dies. after ca 100 yards the condition goes away and engine runs properly.
following parts were changed recently
engine harness,
3 ignition coils,
plugs,
plug connectors,
OVP resoldered

any ideas and suggetions highly appreciated

greetings

reinhard

There is NO such thing as re-soldering an OVP relay. They often times fail internally or at the contacts and can't be repaired.

First replace it, then look further.

They almost always fail when hot.

thank you benmac!
will swap OVP with a friend's newly acquired T320. hope this will take care of stalling condition.
regards
reinhard

is ovp 201-540-37-45 interchangeable with 000-540-67-45???
thx,
reinhard

today I insstalled the updated OVP- problem remained the unchanged. maybe another hint: before stalling occours the engine will catch on with what I best can describe as a thump instead smooth cranking and just catching on. wirering harness, coils, connectors have already beed replaced. where to look next??????
thx,
reinhard

Uuuuuuuuuuupp!!!!!!!!!!!!
Anyone please............
Thx,
reinhard

The throttle actuator may be the culprit, have you had the vehicle scanned for DTC's? If so, was there a DTC that referenced Fuel Safety Shutoff? Another relatively common problem on that era of vehicle is the throttle actuator, I encourage having more test's performed before making that expensive guess.

:cool:

no codes- last week I swaped AMM against known good from friend, again no change. what can I do next????
thx,
reinhard

How did you scan for codes??

my automobile club has a brand new computersystem and no code was found at a mercedes dealer a wile back no code was found either.
thx,
reinhard

I assume you used the -67-45 OVP?
Does your car have the 16 pin diagnostic box in front of battery?

OVP has been replaced and yes i believe it is 16 pin (not OBD)
thx,
reinhard

OK
OBD1 would be USA , but I do believe you can still get stored codes from your Euro 16 pin.
Your complaint is so classic OVP, but your changeout should have remedied the problem. Also, remove and re-install the OVP fuse/fuses when trouble appears and see what happens.
My second suspect would be the Crank sensor or possible cam sensor.
These , if faulty , should come up as a code .
I do not know if all the modules on your chassis were scanned , but pins 8 and 14 would be where one would find these possible codes . They may have just scanned pin 3.
You can make a simple tool for this , if you or any friend is handy.

http://members.aol.com/ajdalton7/ledtool.jpg

It sounds like it's time to take a good look at the engine wiring harness. Pay careful attention to the area near the Air Mass Sensor connector. Any arcing in that area will definitely cause running problems.

wiring harness is new ! Mb thought it was ECU-we swapped it against the AMG ECU that did not work than had it checked as working properly be a german speciality firm- it was the OVP! since then cold start problem gone but warm start problem not solved
thx,
reinhard