06 CDI cranks, won't run

[mdelfunt]

Hey team, need some wisdom on my CDI, 290k miles. Engine was running fine at idle, turned it off and then went to start it back up and it won't. Cranks over fine and comes close to starting (chug chug usually to till the starter drops out thinking its running but it never rully runs). It will do this as long as you turn the key off and on. Here's some data to start.
1) I was having a accelerator pedal issue prior to this. A long story but 3 times the car would simply leave me stranded and wouldn't respond to any pedal movement. Change the pedal and it would run up to road a while and do the same thing again. It's important to note that during these pedal failures, the car would start and run fine as often as you wanted it to. So this this symptom is a mystery and the one I was working on when the "no start" occurred but I can't say for sure that its connected at all with the current issue.
2) Only code on ECM is Camshaft sensor and is stored, not active. I changed the sensor already. I am getting the low voltage code because I've been cranking it so much; I keep charging the battery.
3) Watching the scanner real time data, the rail pressure is 450 bar while cranking which seems to be plenty. I don't have a pressure gauge that goes high enough so I'm trusting the rail pressure sensor data. I cracked two fuel lines next to the injectors and fuel is coming out so my assessment is its not a fuel problem. I can see the fuel regulator % on live data going up and down.
4) Its cool outside but not really cold so my thinking is that any sort of glow plus failure would not prevent it from starting. However, I see where people argue this point; some say it will, some say if won't. I have a Mercedes shop manual that list glow plug system failure as a reason for not starting. I'm not sure.
5) I have not changed the crankshaft sensor. I read where people say this is a common problem in not starting but I'm not getting any codes. I've read where the Cam and Crank have to be in sync, makes sense but not sure if this is the issue. My scanner attempts to show me this data but its hard to understand. I can see "not initialized wait_inc", "Initialized Interims", "Initialized resync_overflow", "Initialized verify", "Initialized wait_phase", "Initialized polling" flashing on the screen during the cranking cycle; not sure what it all means.
6) My scanner is a Launch and does fairly extensive scanning but its not a Star. I can see a fair amount of live data and move actuators.

So I don't really know whether the original issue with the Pedal and the engine not starting is connected but its tempting to connect them. I've been approaching the no-start issue separately and simply looking to understand the fundamentals of getting the engine to start and then address the pedal issue after that. Here in the US, there are not as many diesel owners and information on forums, and experienced mechanics is limited. I'll be out in the shop all day today working on this issue so I would love any wisdom from people with experience. Thanks so much guys.

Mark

 

[mersum1es]

pedal issue is very strange, I believe pedal can fail once but doing it again...

deffo plug/controller failure won't prevent starting. It may trigger engine light but nothing else.

Either it is starge electrical issue which is messing up signals (wire somewhere goes short circuited etc), or moisture somewhere. I would go cam/crank sensor route, check wires there (its hard to follow all route to ecu cause harness is hidden most of the way) and try check if they really sync. I remember couple of cases where sensing ring has been loosen from flywheel; or one case where teeth were bent. But that was not OM642 so structure of sensing harware may be different in this lump.

 

[mdelfunt]

pedal issue is very strange, I believe pedal can fail once but doing it again...

deffo plug/controller failure won't prevent starting. It may trigger engine light but nothing else.

Either it is starge electrical issue which is messing up signals (wire somewhere goes short circuited etc), or moisture somewhere. I would go cam/crank sensor route, check wires there (its hard to follow all route to ecu cause harness is hidden most of the way) and try check if they really sync. I remember couple of cases where sensing ring has been loosen from flywheel; or one case where teeth were bent. But that was not OM642 so structure of sensing harware may be different in this lump.

I know...while Pedals were used(ebay), after the the 2nd one I put on failed (or seemingly failed) I said it was no longer coincidental. I had a perfect 5.0 volts on the pedal circuit feed and both pedal sensors said they were bad on the scanner. Whether the pedals were ever bad, or they just appeared bad, is not known at the moment. So that mystery is still one to solve. I was headed that direction when the engine would no longer run - a completely new symptom and appeared with the shutting off the engine and starting it up again, that quickly. That "immediate" failure not to start while previously running seconds before rules out many things in my mind. But, I almost have to treat it as if I didn't have that information and start from scratch (the fundamentals).
Can you help me understand how to verify Crank and Cam sync?

 

[mdelfunt]

I should probably also say that it comes so close to starting that the ECM drops out the starter thinking its running. Maybe once every year when it gets way below freezing here and I crank up the car early in the morning, it will sound and act like it does not.... it takes me 2 or 3 starts in that condition for it to fully run - then its ok after that. This may not be relevant but what its doing now reminds me of those really cold morning starts....

 

[mdelfunt]

Ok guys, here's an update. Changed the Crankshaft sensor, no difference. That means a new Cam and Crank sensor. I also checked the timing gears on the camshafts relative to the crankshaft to see if it had jumped time, but it was dead on. I can't find any wiring issues; they may be there but I can't find it. I opened up all injector fuel lines at the injector to see if fuel was getting to each one and it is. I checked all fuses for the heck of it. Like before, it cranks and nearly starts (caugh caugh, chug chug) but never quite makes it to full running. If you leave the key on, sometimes the starter drops out when it thinks its going to crank, but other times it will crank and crank for a while before it stops. Cycling the key typically always gets another caugh caugh, chug chug - but never a full running engine. Somehow, I have to get the fundamentals of exactly the conditions needed to run established. If you get fuel, air, heat, & compression at the right time, a diesel will crank, right?
One thing that has a question mark for me still is rather the fuel getting to the injectors is enough. I might have thought that if I loosened an injector line to where it was completely off, like I did, that 450 bars of pressure would have made the fuel spray out of that line like a high pressure washer - but it doesn't. It comes out but doesn't appear to be a high pressure. Of course, depending on how much volume the high pressure pump is designed to pump, opening a line to atmosphere like I did may not be super high pressure stream. I can't physically measure the rail pressure (no gauge that high) but as mentioned earlier, the real time data shows the rail pressure to be in the 450 bar range while I'm cranking.

Ok - that's my brain dump. Hope someone can see something I can't....

 

[Smiley]

An air leak on the fuel supply?

 

[brucemillar]

Hmmm. I'm wondering (this is dangerous) if your Launch Scanner, is clearing down the codes when you have asked it to clear them down. I have seen this previously with a scanner, where it did not clear codes without things like, the engine running etc. It may well be worth a few minutes on Google to see if you track this down, for your particular scanner.

 

[mersum1es]

450 bar is enough.

You are right, pressure is built by load. 'Bottle' system and pressure will rise. Cracked open pipe = atmospheric 'back' pressure = nearly the same pressure in rail. And when injector is opened by solenoid, it depends on flow capability, can pressure be maintained.

Can you see live data at fast sample rate? What happens when injection starts? It sounds very much like fuel pressure problem, and it could be either leak of injectors, delivery of hp pump or starvation in suction line. You have still few possible fault points, pressure regulator in rail, fuel quantity valve in hp pump, primer pump in tank.

Do the injector leak back test, previous cold start problem was big problem in OM61X engines due to leaky o-rings or leaky injectors, OM64X engines are not drawing air in but injectors are still the same.

You have over 1/2 tank fuel right? Search the 'saddle tank' syndrome... which can be cause by poor hp pupmp or broken venturi system.

 

[mdelfunt]

@Smiley - I suppose it's possible but I can't see any air leaks; fuel would most likely be spraying out if there were.
@brucemillar - I'm not sure what not clearing the codes down would do to prevent it from running but I'm willing to listen. The scanner guides me through a process to clear the codes and it always has in the past. I'll see what I can find on this, if anything.
@mersum1es -
- I don't think I can see "fast" sample rates on this scanner, I'll check.
- The story I've been telling myself is if I have 450 bar on the rail and fuel leaking out at the injectors when cracked, that things like the Pressure regulator, Quality valve, Primer pump, fuel filter are ruled out. Do you agree?
- I haven't done an injector leak back test. 3 of the 6 are only a couple years old.
- I have 21% fuel in the tank according to live data on the scanner. Dash shows about 1/4 of a tank. Again, the story I have in my head is if I have 450 bar on the rail, these kinds of things should be ok. Do you agree?

There is one thing I just started asking myself was should high pressure rail keep the pressure it builds after I stop cranking? While I crank, it builds to 450 or 500 bars. When it fires over, then fails to fully run, the pressure drops to nothing. Should the pressure stay high after cranking stops?

I'm starting to think more about glow plug (or no glow plug) issues personally. Suppose all glow plugs were bad; would I still expect it to start and run?

Whatever the issue is, car was fine one minute, dead the next....all by stopping and then restarting it.

Thanks to all for supporting me on this.

 

[brucemillar]

If the error has not cleared then it may still be present in the system thereby leaving you with the same situation (error) where you started.

So. If you have a CPS error and plugging in your scanner and clearing the error with it, leaves you with the same CPS error, we could guess that:

A: it’s a hard error and the CPS has indeed failed.

B: your scanner is not capable of clearing MB errors.


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[mdelfunt]

If the error has not cleared then it may still be present in the system thereby leaving you with the same situation (error) where you started.

So. If you have a CPS error and plugging in your scanner and clearing the error with it, leaves you with the same CPS error, we could guess that:

A: it’s a hard error and the CPS has indeed failed.

B: your scanner is not capable of clearing MB errors.


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ok, CPS shows stored but not Current. Does that lead you to other conclusions?

 

[brucemillar]

ok, CPS shows stored but not Current. Does that lead you to other conclusions?

Ideally you want it cleared to be sure that it is a true error (or not).

Then you can try to start again and see if it brings the error back again. If it does. I would be thinking CPS.

WARNING: this is what I would do. It may not be what the experts would do or recommend.


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[mersum1es]

Yes fuel pressure looks good, so probably it is not problem but only thing I think; something happens when injectors are actuated - excessive leak in one injector or when pressure is controlled after moving from starting 'state' to run mode, pressure regulator device (either of valve) fails.

As above, If you really are able to clear CPS error code and it returns even at stored, most likely there IS something...

Edit: I never checked how fast pressure drops but I think it will come down fast when control valve is not energized

Edit2: Inline CDI engines are GOOD starters, even without plugs they will start unless below -10 - 20C...

 

[mdelfunt]

Yes fuel pressure looks good, so probably it is not problem but only thing I think; something happens when injectors are actuated - excessive leak in one injector or when pressure is controlled after moving from starting 'state' to run mode, pressure regulator device (either of valve) fails.

As above, If you really are able to clear CPS error code and it returns even at stored, most likely there IS something...

Edit: I never checked how fast pressure drops but I think it will come down fast when control valve is not energized

Edit2: Inline CDI engines are GOOD starters, even without plugs they will start unless below -10 - 20C...

Do we feel the Camshaft sensor (CPS) will prevent it from starting? I replaced it and the crank sensor. I can try and clear it again when I get home today but I had thought it might not run good but it would crank and run if CPS were bad. Sounds like you feel differently?

 

[mersum1es]

Crank sensor is need all the time, camshaft sensor at start. Yes it will crank even either of them faulty. If fault codes comes back its probably bad intemittent contact somewhere. edit: can Launch show how many times fault has been triggered?

BTW here one non-starter culprit (hope you can see pic)
Mersuforum.net • Informaatio

 

[brucemillar]

As I understand it -usual caveats apply - the Crank Sensor would/could stop the car starting, as it sets the flags for fuel, air & sparc = crank position.

The CAM Sensor is more fine tuning of the above so would probably/possibly allow starting but may be very lumpy, as it is not fine tuned. .


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[mersum1es]

Usually Cam sensor gives only indication which stroke engine is (as it is 4 stroke, there is always 2 possible strokes per crank angle). If sensor data is intermittent/ inplausible, sync is not possible.

 

[mdelfunt]

Ok, I may have found the demon. I pulled the ECM out and found some oily looking substance down inside the front connector towards the rear of the car. So the back several pins were soaking in something. It looks like engine oil but I have no idea how it got there. I had to come down the wiring harness. There was no trail of oil anywhere. Suspecting that whatever it is might have run down through the connector and entered the ECM so I took the cover off the ECM and I can see some signs of moisture inside. So I suspect the ECM is fried. If so, it may also be the culprit of the Pedal problem I started with. So now I need to find a ECM without paying a fortune. Below is all the data off the existing ECM. If there's any special guidance I need, please let me know.

A648-150-42-79
CR3.43 3.2L
FD 05M11
HW 39.04
SW 34.05
Bosch - 281-013-219
23.11.05 1039S00000
59123b1894 0201

 

[Alexandru]

Hi everyone,
I am new to the forum, sorry if I highlight the same issues here, but still cannot find the info I'm looking for.

2007 E320 CDI with 140000 miles on the clock
Wouldn't start in the morning (temperature outside 8+ C so not cold at all). If I keep the ignition on for 2 minutes, then it starts straight away. Does this sound like a lazy fuel pump or air in the fuel pipes? This only happens when the car was parked for a night or so.
As soon as it starts first time (after waiting 2mins with the ignition on) , if I turn the engine off right away(without letting it warm up) I will turn the key back on and it will start straight away, easy, like it doesn't have any issues.

Had it scanned yesterday:
2195 o2 Sensor
2270 Glow Plug
2138 Glow Plug 6
2137 Glow Plug 5
Nothing showing on the fuel system

Would a Star Mercedes diagnostic unit narrow down and point directly to the problem?

Despite that I have 2 x glow plugs faulty, I remember my 2007 CLK 320 cdi had the same plugs faulty but started first time every time, so I am thinking of a fault with the fuel system and not the plugs. I will change the glow plugs anyway, but just need your advise guys as I can see that some members have a very wide knowledge here.

Thanks in advance