MBNUT1

Wow I am more that impressed with your diligence in this process. We are learning a ton through your efforts.

juanmor40

I think the correct emoji is

I work in software development, and i have too many fingers to count the number of people with this level of commitment and discipline to carry a root cause search. On top of that, the effort required with mechanical components. Just admirable

MBNUT1

Root cause analysis was by far the favorite part of my job.

S-Prihadi

West,
If you hone your electric 101 and use a scope and pressure transducer......... your existing mechanicals 101 is already so good.....the result will be AWESOME !!!

Cylinder pressure transducer at cylinder 1 and with pressure differential at intake manifold can pick up amazing details of compression real time activities without removing cover to see internals.
However I realized that M276 3.5NA is NOT FRIENDLY at all for troubleshooting COP and injector when and if engine need to be running too
The whole giant black plastic engine cover aka intake aka PCV aka throttle body too.......... wow wow, no fun.

I hope this last fix you did on the valve thingy would be the final 50% of the solution... yeahhhh

Westlotorn

Thanks guys but a sharp guy would have noticed the offset in the one valve spring when he found the bad rocker arm. I was in there with a mindset to fix the broken cam adjuster and the cam sensor wheel. Did not pay enough attention to the valve spring retainers. If this was the issue all along I will kick myself for that miss. I very much appreciate the tips and help along the way. Fingers crossed this might be a solution.

S-Prihadi

West, about your COP's pin 2 W11 wire connected to pin 1 W16/5, it may "silence" the signal of firing confirmation the COP sends out on W16/5 as Ground Signal and may produce a
false misfire information to the ECM. I have discovered the actual function of W16/5 ground wire for my COP.

I completed the test on the COP here : https://mbworld.org/forums/e-class-w...coil-plug.html
However it is based on my engine COP which is not the same Part Number as M276.9 3.5NA or M278 or M157 COP's which all these 3 engine variants uses the same COP Part Number.
That is why I request you to measure ohms for old MB one and the aftermarket one and let me have your old MB COP part number because I am wondering why would MB
need to go into such trouble making different P/N for my engine' COP and only for my engine variant.

The COP full test also answered my question as to why my Pin 1 W16/5 is not using bigger wire size of 1.5mm like your COP, instead I get 0.5mm size only.
Since on my COP pin 1 W16/5 is purely a Signal wire and not load/current carrying wire like Pin 2 W11 ,hence that small baby size 0.5mm is enough.
I am hoping the Ohms value from your COP could tell us what are the differences between your COP and mine and how does your COP signal the ECM that firing confirmation ?
Thanks

Westlotorn

I think I am safe, all of the grounds I added follow what Mercedes did. The Brown wires on the passenger side are backed up with a new heavy ground wire that goes to the valve cover same as the W11.
The driver side or left side of the engine has two new grounds but they are from the X26 which I believe goes to body ground and the Brown White wires at the computer harness which also ground to body grounds so through dumb luck I match the factory choice and should not cause issues.

Westlotorn

My coils are not the same as yours I will include a photo of the OEM and one of the replacement coils on this engine. Not tested yet but I am at the point where I install the coils and manifold to see if it runs. Getting anxious.

Westlotorn

I typed an answer and photos that appear to have gone into no mans land. I will try again but need to get back to work.
My coils are different than yours. Do not have the needle test port like yours. My coils both OEM and aftermarket only ground on one side, the bolt hole behind the connector is ground on both coils.

OEM Coil Test Pin 1 to Pin 2 7.93 K ohms Aftermarket coil Pin 1 to Pin 2 test 35.26 K ohms

Pin 1 to coil ground bolt hole OEM 7.93 K ohms Aftermarket test 35.23 K ohms

Connector wire test to engine ground. Coil 1 and Coil 2 .02 OHMS, I found my test clip alone was losing .01 ohms so ground is very good.

MBNUT1

You're getting anxious? Been on the edge of my seat waiting for the result!

Westlotorn

Well, NO JOY at all. The damn misfire is exactly the same. I am ready to send this car off a cliff. Not sure what if anything to check next. I am swapping coils and plugs again just to see if one died in the process but really not sure what next to check. I am leaning towards tearing apart the wire harness on the passenger/right side again near #1 and tracing to make sure I did not miss anything. Time for a cold beer or 4 to think this over.

MBNUT1

Well the valve keeper was something that you clearly had to do regardless.

Westlotorn

No doubt. Lucky both did not come out and drop that valve down on a piston.

MBNUT1

Ok. So exactly what happened on the test drive after you put everything back together?

Westlotorn

What test drive? Mis fired right away on start up. No need for a test drive. It is running on 5 cylinders.

MBNUT1

Did you clear the misfire indication ie the bit that tells it to shut off the injector? If so this should now be easier to find.

Westlotorn

I have done that at least 30 times now so pretty sure I know to do it each time. I have actually got to a point where I clear all codes AFTER test runs so it is ready for the next start up. Still trying to find out why, The fact that is can come and go has me back thinking electrical. I did a running compression test just to look for differences and cyl 1 and 2 were identical while running. #2 never has a misfire so compression is not a factor. I am going back to check the injector wires so the manifold is coming off again.

S-Prihadi

Don't worry, I will keep helping you how ever I can.....



Too bad our COP is not the same, but the numbers are so vastly different for isolation value between Pin 1 and Pin 2 between my COP and yours.
I have 41 mega ohms while yours 7.93 kilo ohms for MB unit and 35.23 kilo ohms for aftermarket unit.
Are all 6 old MB COPs have the same value of 7.93K ohms ? And the aftermarket unit also all 6 at 35.23 kilo ohms ?




One thing for sure, your COP and mine is the same for its Main Power Ground, which is W11 , aka Pin 2.
For your Pin 1, it certainly would be similar in function as mine.

=================

Up to this point wiring harness becomes the #1 suspect.
You have swapped known good coils and injectors too often already to cylinder 1.
The fact that at one time it can be misfire free for 30 minutes of run at low load, is another confusing clue.

Since you mentioned someone been in this car already : did your friend got the car for his daughter with this existing misfire when purchased or the misfire happened only after few thousand miles of use ?
I know you did all these : West wrote : I am trying to help a friend repair his daughters E350, 2013, M276. So far, replaced both Cam intake cam adjusters, removed all 4 camshafts and found 3 of 4 cam sensor wheels had moved on the camshaft
Me write: + all new spark plugs + how many COPs ??

==================

There is one more inspection you can do, since you mentioned : someone been in this car already
A. Make sure the Pin 1 and Pin 2 of COP #1 did not get its female terminals at COP, their location swapped one for the other.
At COP Pin 1 to W16/5 wire supposedly 1.5mm Brown-White. Pin 2 to W11 wire supposedly 1mm Brown.


B. The intermittent mild short to ground test.
Disconnect battery negative post , disconnect both connectors F and M at ECM and all COPs connector's to be disconnected from their COPs.
FOR COP1 only this test : use continuity test first, before resistance test as if your beeper in continuity is a fast response one,
it may be faster to trace but re-confirmation need to be done with resistance-ohms, because continuity beeper on some DMM can alllow up to 50 Ohms and still beep-beep.

1 lead of DMM to engine block, say the red lead. The black DMM lead is to Pin #3 and #4 using your DIY probe pin.
While black DMM lead with DIY probe pin is in the female terminal, press and shake wire harness slowly, hoping if there is mild intermittent short to ground the beeper of DMM can alert you.
Usually we do this to find broken strand of wire inside the insulation, by waiting for beeper sound to intermittently stop, but we can do the opposite to find potential mild and intermittent short to ground/cylinder head.

===============


C. Wire isolation test between W16/5 and W11 wires.

West wrote :
I think I am safe, all of the grounds I added follow what Mercedes did. The Brown wires on the passenger side are backed up with a new heavy ground wire that goes to the valve cover same as the W11.
The driver side or left side of the engine has two new grounds but they are from the X26 which I believe goes to body ground and the Brown White wires at the computer harness which also ground to body grounds so through dumb luck I match the factory choice and should not cause issues.

I am assuming you add 2 new grounds at X26 at Front SAM side which would be female terminals in the X26 ( grey color if on my engine ). Male terminals in the X26 would be the engine side ( black color on my engine )
If you disconnect X26 ( and both ECM M-long and F-short connectors ), by right the engine wiring harness and all COPs has no access to W16/5.
Then, the COP connector Pin 1 to cylinder head should not have any continuity when tested with DMM or any resistance at all, should be OL.


==============

D. I assume you don't have an insulation tester, so let's improvise just in case the mild short is obvious enough, if there is any.
Injector #1 wire pair only. ECM connectors both F and M disconnected from ECM. Battery negative post disconnected.
This time we test one by one injector wires possible mild short to ground/cylinder head.
You only need to remove connector of injector #1 as no other injector share any wires to any injectors, unlike COP with its splices.
Pin 1 ( and then Pin 2 ) of injector connector to one DMM test lead, the other DMM leat to cylinder head. Using continuity first and then resistance-ohms.
Also test Pin 1 to Pin 2 of injector connector, just in case some insulation between the two wires running twisted to one another has small failure/wound points.
Don't get your hand touching the DMM leads because it can read your body resistance, if me in the humid tropics a light touch at both leads will give me 1 mega ohm, dry hand.
Press-shake-pull wire harness to let it touch surrounding "offending metal/conductor", while test in progress. OL is what the DMM should read.
If using insulation tester we test both wire pairs together so it is against 2 layers of PVC jacket of the wires, and one by one copper strand against its own PVC jacket,
below 40 mega ohms at 250V DC its a fail, should read 100+ mega ohms.

That's all I can think of today.

MBNUT1

Since it is failing straight away it sounds like it is no longer intermittent which in my view will make it easier to find. Can you now confirm that the spark plug is firing?

Westlotorn

I am not leaning towards a COP problem, previously I had my timing light on the #1 cylinder and engine running Timing was good, reading #1 so there is spark and it was on time. I put a plug in the coil wire and again engine running the plug was showing a very good arc. I plan to do this test again today to see if my spark has gone away.
The wire diagrams provided showed 2 wires going to the 16/5 ground from X26 and from the smaller computer connector. Since I could not access the 16/5 ground in this car I tapped in to both of those wires and connected them to a body ground. Same as 16/5???? That is how it is set up now. So new wires added so far. One new wire connecting to the Brown wires that come from the COP on the passenger side and 2 new grounds that come from the computer connector/small and one from the X26 connector on the driver side. Since this one injector keeps showing voltages that are not the same as the other 5 injectors, voltages stayed the same with 3 different injectors and 2 computers now so maybe there is something still not found on the injector side of this??? I did load test the injector wires again yesterday, wiggled all the harness looking for spikes and found nothing so far. The owner, my friend purchased this for his daughter as is. She likes the Paint, Wheels, and large base in the trunk. Yes the issue was formerly intermittent but now seems 100%. Maybe it can be found now???

Westlotorn

With #1 dead, not firing at all I connected my spare coil up to # ! wire harness. Grounded the coil and grounded a spark plug in the coil. Started engine. Zero Mise fires from the coil side. Coil is working fine. Timing light hooked up shows the Timing is working right with the coil and shows timing at idle is correct.
Now I know I have Spark and it is on time. i have compression, confirmed again yesterday. The only missing elements are Air or Fuel. We are not getting one of these when needed. The spark plug pulled after several minutes at idle with the coil disconnected to that plug is DRY. Not wet with Fuel. The exhaust smells fine. Not Rich with Fuel. For some reason #1 is not sending fuel to the party when needed.
Cylinder 2 and Cylinder 3 operate on the same camshaft, the same fuel rail and fire just fine, no mis fires. So Either the injector is not being told to open and spray fuel or there is no fuel at this injector when it happens. Two computers failed to supply #1 fuel. 3 injectors fail to send #1 fuel. That leaves us with a wire issue at #1 or a blocked fuel rail at #1. If a rag or something was sucked into the intake blocking off #1 I would think the #1 spark plug would be soaked with gas? It is dry, new plug turned black? Not dry and clean white as if it had been burning perfectly or still new. Not soaked with fuel? If I have no fuel what is turning this black? Black would be carbon from burning fuel poorly, excess gas normally? Head gasket blown between 1 and 2??? #2 has no misfires and same compression as #1. Leak down test on #1 showed near zero leak??? This one just does not add up for me. All 4 cams show to be in sync according to the computer. All 4 cam sensor wheels are matched to the marks on the cam and wheel. All 4 cam sensors when removed show the cams to be in sync looking through the opening for the sensor.
Something is bad wrong but has not showed its head to me yet? Tested both Coil wires from the #1 coil to the computer harness again under a 5 amp load. Did not see voltage drop or not much, 220MV and my test wires showed they were measuring 100 MV voltage drop so I think my wires passed? There are only so many things needed to make the #1 cylinder work properly. This one still has me stumped.
Again, I am not the first wrench to try and fix this car. The owner did take it to a shop before he asked for my help. He told me the shop is a real expert. The shop installed a new coil and then told him he needed another new coil. I understand since I have chased this stuff and not fixed it. It is sparking so I want to ignore the Coil On Plug and focus on fuel.

MBNUT1

The reason I asked the question is for you to be able to eliminate the coil.

I appreciate you laying out everything that you have looked and agree with your logic.

Are you able to access the injector connector in situ or do you have to pull the manifold?

Westlotorn

Manifold has to come off to see the injectors unfortunately. Gets in the way of testing.

S-Prihadi

I re- paragraph your writing for easy read, for me.


NOTE 2 : The spark plug pulled after several minutes at idle with the coil disconnected to that plug is DRY. Not wet with Fuel.
The ECM is probably at this point in time with spark-plug out of cylinder albeit COP is attached and is firing but firing in open air, will produce a misfire code from the
detected abnormal speed variation of the crankshaft and immediately command INJECTOR KILL to save the catalytic converter.
This is good info, now we know that the safety protocol performed by ECM is to kill injector only and not the COP, perhaps because the wiring to the COP is deemed "normal" by ECM,
but crankshaft slowing down due to no combustion energy at Cylinder 1 is the dead give away.
Do note that the definition of misfire for the ECM is crankshaft speed variation where it knows there is missing "energy" at X cylinder because poor or no combustion/explosion or
wrongly timed combustion is taking place.


NOTE 3 : That leaves us with a wire issue at #1 or a blocked fuel rail at #1.
Yes, there is a possibility of injector #1 wires pair issue. Blocked fuel rail would be quite easy to inspect I think, but you need to open the rail again.
From HP fuel pump to the fuel pipe entry into Bank 1 fuel rail/pipe, this entry point is closest to injector #3 and injector #1 is the unlucky child at the end of the fuel rail.
If indeed there is dirt, the injector #1 being at the very end of the fuel rail could be the unluckiest location.
Say a broken big black o-ring of injector #2 or # 3 upper stem, part of it was stuck inside the fuel rail and got into the end of the fuel rail aka injector #1 location.




NOTE 5 : Tested both Coil wires from the #1 coil to the computer harness again under a 5 amp load.
Did not see voltage drop or not much, 220MV and my test wires showed they were measuring 100 MV voltage drop so I think my wires passed?
Sure it has passed voltage drop test. What I was hoping to see for is the isolation test of the wires of COP's pin 1 and pin 2, as described on my previous post, as C.
This is just to be sure that the whatever happen to the injector, it is not because of COP firing confirmation signal from Pin 1 ( w16/5 ) is lost or distorted.
With modern engine computers software the dominant Boss to operate what and when, our mechanical bias thinking need to accommodate this software thingy.

C. Wire isolation test between W16/5 and W11 wires.
I am assuming you add 2 new grounds at X26 at Front SAM side which would be female terminals in the X26 ( grey color if on my engine ).
Male terminals in the X26 would be the engine side ( black color on my engine )
If you disconnect X26 ( and both ECM M-long and F-short connectors ), by right the engine wiring harness and all COPs has no access to W16/5.
Then, the COP connector Pin 1 to cylinder head should not have any continuity when tested with DMM or any resistance at all, should be OL.

and also Injector wire test, not load test, but as below in D.




What I have not done for COP test, which I kind of regret now, but will do it next week is :
What happen if my COP pin 1, which is wired to go to W16/5 firewall ground.....along the way, the wire get's a little cut and touched cylinder head which is W11 cylinder head ground....will it matter ?
I mean both Pin 1 (W16/5) and Pin 2 (W11) are at its final destination : are GROUND-ed to car metal anyway.
But why would MB engineers took the trouble to isolate Pin 1 ( W16/5 ) to make sure it is only wired to W16/5 stud ?, which is also the ECM's main Power Ground/Minus.
I know COP will fail to fire when Pin 1 ( W16/5) is disconnected, but I do not know what happen if I on purpose connect/short Pin 1 ( W16/5 ) to Pin 2 W11 or cylinder head which is the W11.
Too bad I can only later test this W16/5 and W11 marriage during idle and not during WOT.
My COP male connector test wire kit does not have a true female plastic connector body ( only female SLK 2.8 terminal ) for me to have confidence in driving around with it to do WOT, too much vibrations.

juanmor40

West,
Since the intake plenum is out one more time, not sure if you already checked there for leaks around the lower intake manifold and cylinder #1. Not only at the top, but at the bottom where it meets the cylinder head



Fingers crossed this is the last opening.