2002 ML320 gasser with 170k miles
Gradually increasing loss of power, now while parked it idles poorly after a couple of minutes after starting, Still starts fine.
Fuel rail pressure starts to oscillate between 45 and 60 psi as the symptoms develop.
I have replaced the fuel filter, fuel pump and K2 fuel relay.
I sent the ECM out to Module Experts in FL and they say it is fine.
I can feel the fuel pressure test gauge line vibrate as the engine starts to stumble at idle.
Revving will sometimes cause major stumbles.

Anyone have any ideas? Cus I am clueless!

 

Is the Check Eng. Light on? It could be faulty injector/s.

Codes must be read in the ECM or everything is [purely guesswork.

 

I have my own Star compatible OBD reader. There is a check engine, but related to oil pressure/level/quality from defective sensor. have been driving with the error code for over a year.
No fault codes that relate to engine operation

 

What is the code # for the oil pressure problem?

There has to be a code/s in the ECM. for this problem.

 

Fualt codes:
[B1(oil temperature sensor) / B40/2(oil pressure sensor): Signal unreasonable (P1999) or [B40(Oil sensor(oil level, temperature and quality): Signal unreasonable(Oil Level) / Line mixed up(P1999)

 

At any time with this problem, does the CEL illuminate?

 

No CEL
I am going to check the supply voltage to the pump at the tank and check the pressure at the pump and at the filter/regulator.