S400CDI cold start problem

[RIDER]

Hello everybody.
I have 2001 S400 cdi.
The problem is, that engine runs about 2-5 seconds after cold start and then cuts off.EPC appears on dashboard. It happens until the engine temperature will reach 50 degrees.
When engine hot everethyng is ok.
No any diagnostic faults appears.
I`ve checked everything with STAR diagnosis system, all activation test are ok.
Does anybody knows, or had or heard about same problem?
Thank you.

 

[alexander patie]

rider, there simply WILL be fault codes stored if the epc warning comes on - that is a fact. i suggest you observe the clear fuel pipes for air circulation while you have the fault.

 

[RIDER]

But there is no any fault codes, because i cheked it by myself.
Now I will do it on cold engine after work, when it will cuts off.
Star diagnose is in the trunk.
May be i will catch some.
But anyway they should be stored i understans that but...
There is also cold start test procedure in this star diagnose, i will check it as well.
I didn`t cheked that clear pipes, if there is air bubles it means that low pressure line sucks air somwhere.
But all lines are clear without any leakage.
Air bubles can be caused by faulty relief valve.
It`s located near electrical pump under the car.
It s interesting that all this happens only on cold engine, if temperature higher than 40, everything is ok.
If it sucks air, why only on cold engine?

 

[RIDER]

P2001 appears when engine cold an cuts off only!

 

[Neebo]

Injectors leaking internally ? I.e through spill pipe Could this be worse on colder mornings,a vessels ontop of injector with star injector test ? Only a thought.

 

[Neebo]

Just re read that and did not understand myself !
Carry out an injector leak off test with star vessels catch diesel leak off and determine if it's too much.

 

[RIDER]

Injectors been tested.
No leaking.
It seems to me that there is some problem inside ECU module.
Some electronic chip inside faulty.
I will try to replace it from other vehicle, or preheat it little bit before start in the morning.
Because this fault code tells you to check voltage on 87 terminal for ECU.
And appears only when engine or ECU are cold.

 

[alexander patie]

and HAVE you checked the voltage at the relevent terminal during the fault?

 

[RIDER]

Not yet, because i`ve returned this Starr diagnosis to my friend and don`t have WIS at the moment.
So I need pin diagramm for socket A and B

 

[RIDER]

This is ECU problem.
I preheated ECU, and everything was ok.
I did it three times, to make sure.
Some component inside, which responsible for voltage supply to CPU.
Any ideas???

 

[alexander patie]

hello again, that IS interesting! it could be a dry solder joint, but i think more likely is a faulty output stage to the injectors - you could have the 'transistors' checked...

 

[Arnie]

I have had the same problem on a G400.

It seems that the problem is a faulty component in the ECU itself.


Cdi engine: EPC error: engine dies: Help! - Benzworld.org - Mercedes-Benz Discussion Forum

 

[spanner]

Poor cold start

This is interesting.
We have a customer's G400 with the same issue.
We have Star and know how to use it.
We have WIS and TIPS
Problem only apparent when vehicle left unused for a few days and then only when ambient less than 10 degrees.
Engine would initially start and then die. Attempted restart would fail, cranking only.
If the car was locked and then unlocked then the engine would again run for a few seconds then die.
We noticed that if the ignition was switched on to pos 2 but not crank and wait 30 seconds then engine would sometimes start and remain running.
Problem detiorating over time and these solutions no longer work.
If the accelarator is held down during initial start and 2000rpm maintained until coolant temp of 40° is reached then engine will idle fine and no further problem for the rest of the day.
We detected low battery voltage and renewed the battery; battery voltage restored but fault remained.
We detected both air mass sensors out of spec and renewed; no change.
We renewed CPS; no change
We detected low voltage at the output stage of the glow plug relay; renewed all glow plugs and voltage output returned to normal but fault persists.
Checked all injectors for leakage and carried out smooth running tests etc. all within spec.
No Fault stored in diagnosis.
Alternator renewed after consultation with MB technical support.
No change.
Car is returned to customer while we try and work out the next POA. We might send the ECU off to be checked, but we'll be checking voltage at ECU first..
If anyone has any more ideas I'm all ears!

 

[holodram]

has the problem been fixed yet then?
and what was the problem?

thanks

 

[George Fragkos]

hi,,,,
I have also the same problem with an S400 CDI , cold start..
Please let me know if you solved the problem? . And how ??

 

[spanner]

I had a PM asking for an update but it's better for all if I post the update here so everyone can see it.
Problem was water ingress to engine ECU. New ECU was required. (we didn't bother trying to have it repaired but this was probably possible).