S320 Cdi Fuel pressure switch failure.

[television]

You can't disconnect and plug the egr vacuum pipe on a CDI, the complex electronics sense the disconnection and put the engine into 'limp mode'

(I know 'cos i've tried it)

Thank you

 

[franey]

What about...............................?

If one injector was faulty would this shut the system down altogether?

The reason I ask is because when it last went on a star machine some months ago, I was told No.4 injector was not performing 100%

 

[BlackC55]

Yes

 

[franey]

Battery fully charged.
Washed, vac' d, new carpets put in, all while I was waitin for the new injector. Treated her very nice.
Collected injector (had it refurbished) today and fitted it, coupled it up, tightened everything.
The damn thing, she will just not go. Why is this, why me.?
Aaaaaaaaaaaaaaaaaaaargh.

 

[Ultymate]

Similar to jay's code.

P2021 Intake Manifold Runner Position Sensor/Switch Circuit Low

The immobiliser is a red herring, if the DAS3 isn't working the engine won't turn over.

The immobiliser theory was not a "red herring" as that is usually a "deliberately" misleading statement and secondly most modern diesels are not only immobilised by breaking the starter circuit but at the same time interupting the electronic injection circuit i.e. no pulse (dwell) at the injectors. So at this stage I still would'nt rule out an immobiliser issue.

 

[sweeper]

Battery fully charged.
Washed, vac' d, new carpets put in, all while I was waitin for the new injector. Treated her very nice.
Collected injector (had it refurbished) today and fitted it, coupled it up, tightened everything.
The damn thing, she will just not go. Why is this, why me.?
Aaaaaaaaaaaaaaaaaaaargh.

Not Mercedes i know, but i started dealing with Euro 4 spec engines last year, all with Bosch common rail injection systems, we have three common issues for not starting so far (ie engine turns but does not fire)

1. faulty fuel pump (very low pressure on cranking)
2. crankshaft postion sensor faulty
3. cracked fuel filter housings allowing air to be drawn in.

First thing i do is hook up diagnostics, clear any faults and try to start, check for any fault codes, if none show or fuel.rail pressure shows fault i use diagnostics to check fuel rail pressure whilst cranking Eliminating electrics by disconnecting fuel pressure regulator wires, check for filter fault if fuel is apparent at pump and still no pressure, replace pump or regulator (if available separately).

 

[Dieselman]

The immobiliser theory was not a "red herring" as that is usually a "deliberately" misleading statement and secondly most modern diesels are not only immobilised by breaking the starter circuit but at the same time interupting the electronic injection circuit i.e. no pulse (dwell) at the injectors. So at this stage I still would'nt rule out an immobiliser issue.

I didn't mean that you were deliberately misleading the OP but it can't be the immobiliser as that is a function of the EIS. If the EIS fails to correctly interrogate the key it won't even allow the key to turn let alone send a 'Run' signal to the engine ECU via the CAN.

All engine functions are controlled by the engine ECU including starter, run, stop, and autostart function.

Once an initial run signal is sent from the EIS the CAN could be disconnected and the engine would still run as another command can't be sent to it from the EIS.

 

[Dieselman]

Friend came with a code reader and it showed P2021. I googled it and it went on about a starter relay? Huh.??

Have you fixed the intake flap motor yet?

With this part showing a fault and the EGR valve stepper motor whistling it makes me wonder whether you have an electrical harness fault or power supply issue.

 

[franey]

Hi Dieselman.
Still no further on.
Are you perhaps suggesting the egr is not playing ball?
And is that the fancy looking motor thingy on top of the inlet manifold?

(that's what's making the whistling noise)

Cheers.
Also, surely this would not prevent starting?

 

[Dieselman]

I am assuming your manifold and EGR setup looks like this.

http://www.detali.ru/cat/oem_mb2.as...GA=722.626&CT=M&cat=63T&SID=14&SGR=030&SGN=01

If so the screeching is the stepper motor trying to drive in two directions at once. This would indicate an ECU fault as the drivers are built in. It needs investigating, possibly an ECU test might be in order.

 

[franey]

I am assuming your manifold and EGR setup looks like this.

http://www.detali.ru/cat/oem_mb2.as...GA=722.626&CT=M&cat=63T&SID=14&SGR=030&SGN=01

If so the screeching is the stepper motor trying to drive in two directions at once. This would indicate an ECU fault as the drivers are built in. It needs investigating, possibly an ECU test might be in order.

Thanx DM, will check out in the morning and let you know.