C220cdi om651 has me baffled

[Mattyb1984]

After speaking with actronics it's an ecu they cant do much with unfortunately. However he did state that usually if the ecu is at fault it would effect 2 cylinders rather than just one ak the time. Back to head scratching lol

 

[ajlsl600]

You dont have obstruction in fuel pipe to inj 3 ? Again chance of this on 2 motors seems slim
I believe yr fuel press is taken from common rail after that?
You may have continuity along wires from ecu ,but any chance wires pinched to earth before ecu ?
Again difficult to see that on 2 motors unless you followed same procedure removing refitting both motors ?
Sort of clutchin at straws

 

[Mattyb1984]

No obstruction to cylinder 3, fuel getting through. I'm convinced it's the injectors.

 

[Uncle Benz]

Can you back-probe the injector plug and measure the voltage, compare to the others?

 

[M80]

Please feel free to ignore as I don't have the expertise of the other chaps here.

Fuel pressure good in common rail, or it wouldn't start.
So fuel good, pump good.

Compression good on all cylinders, so rings, pistons and valves good.

You've eliminated injectors by exchanging.

I would suggest it not to be the bleeding issue or compression would be down.

I would suggest it not to be the pulse feed to the injector/s or the compression would be down.

Both engines have had intrusive attention since last running correctly.

Are you sure the timing is correct?

 

[mattseabrook]

injector pulses are difficult to measure as they are relatively quick, a noid light would be useful here to see the injector signal.

Injectors tick as they fire, can you hear this?

Agree with above that although you may have continuity from the ECU, it may also be shorted to ground (or another wire in the loom) An insulation tester is needed here.

 

[umblecumbuz]

You dont have obstruction in fuel pipe to inj 3 ? Again chance of this on 2 motors seems slim
I believe yr fuel press is taken from common rail after that?
You may have continuity along wires from ecu ,but any chance wires pinched to earth before ecu ?
Again difficult to see that on 2 motors unless you followed same procedure removing refitting both motors ?
Sort of clutchin at straws

Er ... it IS affecting two cylinders - only not on the same car (with apologies to Eric+Ernie).

 

[Mattyb1984]

Timing has been checked multiple times, if timing was out I would have thought it would effect all cylinders at some point. When the injectors were exchanged they were for a 2nd hand set. I've just ordered a full set off reconditioned injectors with new c3i codes from ebay. They are coming from germany but at £211 including postage I really couldnt say no.
With these wiring looms it extremely difficult to pinch the injector wires as the loom is on the top of the engine and stays with the engine when removed. All I can think Is the ecu is picking up on faulty injector/s and shutting cylinder 3 down automatically. The only way to rule this theory out is to try a new/reconditioned set. If that doesnt do it at least I have a spare set off injectors lol.

 

[Mattyb1984]

Thought it was too cheap for a set of reconditioned injectors. I've just received a call from germany asking me for a €50 deposit per injector for the exchange of my old injectors. Normally I would be ok with this but as the company is not uk based I'd rather not take the risk.

 

[Mattyb1984]

I've just placed an injector in mid air connected to cylinder 3 wiring and fuel pipe. Started the car and the injector is firing as it should. So this now tells me the ecu is not shutting down the cylinder. This now leads me to believe there is incomplete burning of the diesel which is in turn throwing the ecu into a hissy fit. When I timed the engines up I did so by the marks and when I check the marks their fine. Now I'm possibly thing camshaft issue, lobes spun slightly but then why is compression good?

 

[M80]

When I had issue with a 2009 V6 CDI I was informed that spares couldn't be sourced to recon the piezo injector,
is this now different?

But assuming it isn't one of eBay's strange categories you would have 30 days (from delivery) protection.
I would ask eBay customer services prior to purchase.

 

[ajlsl600]

https://www.google.com/search?clien...HY4wCFEQ1QIwEHoECAkQAQ&biw=360&bih=572&dpr=2#

Guessing timing sprockets on a taper ? Lookin at adjustment method .interestin stuff ,hope dont need to get involved in that.

 

[Mattyb1984]

Could the balance shafts cause this, if they were slightly out of time?

A passing thought is that if the balance shafts are slightly out of sync then could the ecu be trying to over compensate and cannot correct itself? It would mean removing engine to find out but I'm running out of ideas now lol.

 

[ajlsl600]

Really dont know.would doubt it.but way things organised ,today.? But if timed out would expect some eng,drive vib as thats why shafts there to balance things.

 

[umblecumbuz]

If balance shafts, why only one cylinder affected?
Think you're clutching at straws with that one.
Mystery.

 

[Mark A]

Surely no balance shafts on the 220.

 

[ajlsl600]

OM651 I pretty sure has balance shafts.
Not overly a great idea in m view.
Remember them on pajero engines,bearings used to spin blocking oil supply to rest of motor "bang"! A lot used to remove the drive to them fix shafts and carry on.

 

[Mattyb1984]

Om651 balance shafts are built into the main bearing holder which is a stupid design. The entire assembly must be removed in order to check the journal bearings. The more I think about it the more I think I'm clutching at straws with that one as surely it would effect all cylinders not just number 3.

Usually I would say that these symptoms would be an issue with the cylinder either rings, piston or valve but as compression is there it just doesnt make sense. As one engine is freshly rebuilt I could understand it as the piston rings bed in but the other car is untouched in the sense of opening the engine up. I've spoken with a few mercedes specialists and they are also baffled by it.

 

[star]

So have you tried bleeding it via star and followed the procedure? As mentioned, early 651’s are a pain to bleed and always result in a misfire on a cyl.

 

[Mattyb1984]

Bled multiples using star, no difference.