96 C280 with no Injector pulse
 

I have here a fine example of a butchered motor swap.

After the offending tech installed the motor it faied to run...
The Fix: New Crank Senesor, repair to harness for crank sensor.

Now this beast has been out for about 2 months and it returned with no injector pulse.

I have limited data on Mercedes as I am using Mitchell :rolleyes: Which has been of very little help.

I have spark, I have fuel pressure, I have compression, I have power to the injectors. What I do not have is the ground pulse to fire the injectors.

The cam sensor has been replaced, the ECM has been swapped, all ground and power wires I can trace via Michell has been done and are O.K.

What am I missing here??? :confused:

Still looking for some ideas... :(

• I am using a Snap-on MT2500 scanner in Generic Mode (No German Cartridge)
• No Codes, but that does not mean there are no codes set on the MB side...
• Spark is good
• Fuel Pressure is Good
• Visually and tug tested grouds and checked for power to the ECM at the ECM connector.
• CMP and TDC sensores are new and have been checked for resistance from the ECM plug.
• ECM has been changed with used unit.
• Battery in excellent condition.

I am at wits end on this one, been advised by 2 local German Car Gurus, but they to are sharing my confusion. :confused:

Any help is greatly appreciated.

Just a guess have you erased the trouble codes in the ecm?

Have you checked for injector pulse at ECM?

Battery was flat when it came to me, nothing stored...
When they were trying it would hit one or two cylinders and then nothing.

Scanned car at the time andnothing showed up, that I found out does not mean the ECM has noting stored it means that a real german scanner may find a code but the Snap-on MT2500 may not see it at all, this I found is very common to Mercedes Benz cars.

I did look to see if there were codes after cranking on the advice of a Mercedes Benz tech up the street but again nothing shows up.

Noid liight says no on all 6 connectors, I have checked that all 6 lines have continuity.
I have power to all 6 injectors. This is also on the same line that supplies power to the 3 ignition coils.

Now I don't think for a moment that the car simply broke while sitting there for a couple weeks... I am leaning to maybe it might have been jumped backwards by the lot boy or somthing along those lines...

BUT my BIG question is "What line going into the ECM supplies the ground for the injectors drivers?" which leads to my second question "what lines are used to power and ground the injector driver circuits?"

Also I have used the key and the remote to open the doors to see if the car was simply in a passive anti theft state... I would say that this is not the problem as I believe that these cars stop you from using the starter rather than cutting fuel like a Chrysler.

Could this be caused by the over voltage protection relay?

Long Time
 

TechFromHeck, a long time has passed... I'm with the same problem in a c280. Did you find the solution?