JettaRed

iTrader: (1)

Interesting that cylinders 1 and 4 appear to be outliers, are both at the front of the engine, at the end of the fuel rails, and are across from each other. Also the cam position sensor and cam solenoid are closest to those two cylinders.

S-Prihadi

Ask :
01. What engine/coolant temperature is this reading ? And is this a first test ?
It is very slow for overall cranking speed, if battery is healthy and fully charged, compared to a 30-32C / 90F engine/ambient temperature.
I do not have experience of ambient temperature any colder below 18C / 64.4 F cranking speed, sorry.

If you later can do warmer engine test, say 30C / 86F , with fully charged battery, 20-30 amps charger assist is okey, I can tell you if your battery CCA is already lowered or not.


Back to the Xentry Compression Test result.
This test has no fuel spray, no COP ignition and is battery powered using the starter.
This is a test for the engine to act as an air pump, a compressor if you will.
The faster spinning cylinder 1, compared to the slower cylinders 2nd to 6th, indicated that cylinder 1 is a poorer performing as an air pump, aka more leaky than the other cylinders.
The more the "leak" the easier for the starter motor to crank faster.

This is a relative compression test, where what we want to see is relative differences only.

==========


Why I told you to do at least 2 test is because of lubrication film spread of 1st test usually is not good enough.
If engine been OFF too long and I supposed cold temperature would be bad too.


This is my engine at typical ambient temp of 30C / 86F and engine not been started/run for 30 days. So lubrication film is minimal. Engine oil at this point in time was 9 months old, but only 1.105 KM use.

First test.




4 minutes later 2nd test



See how much better and "normal" when lubrication film has spread.


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


44 days engine never run. Oil at 4 months old, 865KM use only.

1st test




2nd test



See the average speed of 200 RPM
A healthy battery with suitable CCA rating, with or without 20-30 amp charger/maintainer assist, if at 30C ambient temperature should be able to crank at the least 180 RPM to 190 RPM by
2nd Xentry Compression test, on a normal healthy compression engine.


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


You have done a lot to narrow and fix this Misfire Cylinder 1 issue. I am listing below of important ones relating to a cylinder pressure capability verification.

1st post
1.Compression #1 cylinder 180 psi
9.Send cylinder head to mashine shop for inspection of the valve seats and springs also pressure test.

7th post
1. 145000 miles
2. 180 psi MAC tools compression tool
3.Check #2 cylinder compression 175 psi



01. Lets wait for the cylinder leak down test first and if possible at least ALSO test cylinder 2, 3 and 5 too as comparison. If you will do 4 and 6 too, even better.
If leak down test does not produce a more significant proof that cylinder 1 is "more leaky" compared to other cylinders..... you need to see how the 0-720 degrees cycle is, Absolute Pressure Transducer wise at cylinder
and Delta Pressure Transducer at intake manifold during cranking.


What I would do if I have the same issue on my engine ?
I would scope it electrically first to really verify that electrically my injector and COP is doing its job and I will do ignition waveform analysis to see it visually.


This is what I mean by electrically.
INJECTOR current pulses in red. COP 5V trigger in green. COLD engine.



COLD start is always 3 injector pulses/spray and later two pulses/spray.




The above red waveform can show if the injector electrically healthy or not. Compare it to a known good injector.


For 2 images above :
I removed on purpose the injector voltage as it is so high and fast, it cause noise to even a 200V picoscope automotive 4425A, unless differential probe is used or 3 other channels are for current clamp use,
where it does not share ground with the injector.

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


This one has injector voltage.

This is how fast the injector open-close for its first spray of a twin spray mode. 0.5 millisecond only....wow.




and then COP test and ignition waveform test........... bla bla bla.



Ok thats all...............



ADD :
Why I said , I will still test electrically the injector & COP is because we need to make sure the wiring harness from ECM to injectors and COPS are okey while under electrical load and routed as-is.
Poor contact or pin fitment issue at wire harness connector side at the ECU or at devices is not un-common, I been once a victim on a friend's M271 new ECU.
It is very difficult to see those female MLK 1.2 connector well- being if only lost of bite is the problem. You need the male terminal to test those female terminals pin fitment.
The more we do troubleshooting on the car, the more we connect/disconnect those terminals and they are rated to be "good" at about 20 to 50 mating cycles only, 50 if silver coated ones.

MakUsa

I will do leakdown test today and post results (last night I couldn’t find the leakdown tool/gauges)
Also the ambient temperature last night was 60F
I will do one more Xentry compression test tonight with warmer engine and battery charger connected.
I will post the results.
Also when I removed the spark plug on #1 cylinder to do the compression test with manual gauge the spark plug was black in the tip!

S-Prihadi

If you are doing warmer engine Xentry compression test and leak down test, before the leak down test......
can you please try once more the regular compression test using the mechanical gauge.
We need to be sure the data/condition is always repeatable.

Mak wrote :
Also when I removed the spark plug on #1 cylinder to do the compression test with manual gauge the spark plug was black in the tip!
Sure it would be, poor combustion does that.

I bet your misfire shake shake wise is not as bad as when you disconnect a COP, as in totally no combustion.
This is my guess based on the Xentry Comp Test and Mechanical 180 psi comp test.
How shaky is it ?

MakUsa

its shaky when cold first start when warm not so shaky
Some times when I start the engine and drive right away I don’t let it idle at all it drives good,power is good and pick up is good feels smooth as soon as I let it idle it’s starts to shake and check engine light blinks.

S-Prihadi

Mak,

One thing I enjoy helping others troubleshooting is, I have to forced myself to learn more too, as there is a good reason for doing so....I get to learn too.

Some background on your M276 car please.
How long ( miles and years ) you owned it and at what mileage when first acquired and up to the point it has this misfire to today, how long have you been at this troubleshooting ?

I have to ask you for the 2nd time, did you clean and inspect the hydraulic lifters when Bank 1 cylinder head was removed ?
Attached the WIS in PDF.




.



This automatic valve clearance adjustment device uses tiny oil passage to maintain its working height. Has check ball too and spring.


Above image from Youtube. Buy new one, don't tear open one.

.

The pink line below is the "collapse" zone, if indeed it no more can maintain oil pressure to fight the camshaft peak lobe when that peak lobe is pushing down on the intake/exhaust valve.









.





Compared to engines without self adjusting valve clearance lifter, the clearance factory wants is only for metal expansion when hot. So small a value.
Damn it was 35+ years ago I was always sending my 1.0 Liter Toyota for valve clearance adjustments every 2,500KM which is the oil change too ....LOL.






Mak wrote :
its shaky when cold first start when warm not so shaky
Some times when I start the engine and drive right away I don’t let it idle at all it drives good,power is good and pick up is good feels smooth as soon as I let it idle it’s starts to shake and check engine light blinks.

Oh oh....to me sure sounds like a "soft-enough" valve lifter. Not totally collapsed but it can sink more than it should at low oil pressure.
When warm it expands and when engine is higher RPM the oil pressure is better, so lifter don't sink much.

Your shake is like what I call a 1/2 race camshaft. I do not know the US term for it, but in my days and British term, I was using a 1/4 race camshaft. Idling not so good, but power is better.
My friend VW Golf has a 3/4 race cam, its idle has to be set 1,200RPM or so, but the power gain was crazy. No VVT back then in the early 80s.

I suspect it is the valve overlap region is where your lifter causing the shaky misfire because your valve opening/closing is kinda wrong for idling.
When you take off or higher RPM, VVT kicks in and that will change the valve overlap, hence smoother for your engine.



https://help.summitracing.com/knowle...SR-04703/en-us



.
.Big Red Arrow below is piston travel direction. The green circle I marked is the valve overlap region when seen in a in-cylinder pressure wave from.









.

MakUsa

Ok to answer your question about checking the camshaft and lifters when cylinder head was removed I can’t answer because was done by different person that I know and %100 was sent to mashing shop together with the cams and lifters to be checked and tested and the mashine shop was told that the engine misfires on #1 cylinder
When picked up from mashine shop the cylinder head they told my friend that they didn’t find anything wrong with it!
Just to let you know also I do this to learn and I like the challenge
No body wanted to touch this car anymore but I like the challenge and I took over maybe with your help I will get to the problem
I don’t know the long service history of the car but it looks good
No oil sludge!
But I think maybe cheap oil was used on the oil changes by looking at the oil change stickers on the windshield!

MakUsa

Also when I let it idle for longer time and engine shakes and engine light blinks without turning the engine off and on take it for road test and in this case has no power!
And I stop turn the engine off and start again and don’t let it idle just drive right away power is good!

MakUsa

Ambient temp. 67F
Engine temp. Values:

First Xentry compression test:

Secont Xentry compression test:

MakUsa

Second Xentry compression test:

MakUsa

Xentry compression test #3

MakUsa

Manual gauge compression test engine temp 85 C

Cylinder 1

Cylinder 2

Cylinder 3

I did test #1 cylinder 2 more times and it show every time little different pressure but it was more than the picture never less!

JettaRed

iTrader: (1)

Have you disconnected your oil pump solenoid? If you don't know what I mean, look through this thread: https://mbworld.org/forums/w212-amg/...solenoids.html

The BLUF is that our engines use a two-stage oil pump that uses a solenoid to control oil pressure in two stages. With the solenoid connected and operating normally below 3500 RPM, oil pressure is restricted to 2 bar. Above 3500 RPM, the solenoid disables and the oil pressure is allowed to rise to 4 bar. This is done ONLY to save gas and nothing else (thanks to government mandates of higher fleet mileage). As a result, there is sometimes inadequate oil pressure to allow the VVT to fully compensate for wear, etc. There are also problems with pre-mature cam wear, HPFP wear, and the like. Many of us have disconnected the stinking solenoid and have enjoyed better engine health and performance. For me, the improvement was most noticed on my M276 3.5L NA engine, like yours.

When I disconnected the solenoid on my C350 and measured the oil pressure with an external mechanical gauge (our cars do NOT have oil pressure sensors), I hit approximately 90% of my max oil pressure at around 1500 RPM.

MakUsa

Leakdown test number #1 cylinder!!

I was surprised honestly I didn’t expect this!!

Chevota

Watching the spark plug fire while dangling is not weird at all, but if you want to step that up you can watch the cyl fire. It'll be trickier with these engines but I would replace the plug wire with a regular old wire, lamp cord, coat hangar or whatever to better see the plug itself. Then with it as dark as possible, you can see the cyl fire. If you leave a teeny gap between the plug and improvised plug wire, you can see both the spark and cyl fire, then you'll know if the spark is the problem or not.
I can explain better if it sounds like something you might want to try.

I don't believe a lifter is the issue because it'll fire with a collapsed lifter, plus you'd hear it. There is no valve overlap at idle, probably none period, so a non-issue.
The A/F mix of .940 or whatever it was is a non-issue as well, it'll fire much richer or leaner than that. Catalyst mode will cause a lean or rich condition, depending on how it feels, so don't expect to see a steady lambda that makes sense all the time. When in open loop mode, when the O2 isn't working for whatever reason, it'll still provide the correct fuel mix.

If that one hole is a little leaner, because it's having trouble for whatever reason, it could be good enough to seemingly function normally but too lean in split injection mode. To test fuel flow I'd floor it and look for noise and spark retard in that hole. I'd imagine Xentry can see that but I also know it's a pita to use and not good at it. I'd use some other method that can record all cyls for noise, retard, rpm and load. If you don't have a tool for that then the Torque Pro app can and costs ~$15 total for hardware & software. Cheap toy/tool either way.

Your power loss that goes away after a restart is, imo, just the ecu pulling power because it sees an issue, and a restart resets that. I would ignore it and restart as needed.
Your compression is more than enough so I'd ignore that as well.

S-Prihadi

Ok we continue.............



2-3% leak only, but at compression TDC. Sweet, basically air tight.



Let's dig some earlier data :

01. Based on front/upstream Lambda of Right - Bank 1, this bank is lacking of breathing air. AFR 13.5 approx. Short of stoich AFR 14.7 when idling.






.
Intake manifold vacuum pressure sensor agrees that there is not enough suction at intake manifold. Less vacuum means piston's suck less air. Below is at 90.75C, so already at HOT coolant.
Since this is still under mild misfire condition, RPM of 560 is kinda low for hot idling. So the lower vacuum reading can be also from the lowered RPM, to a point.





My engine vacuum when HOT coolant 95C. This is a short 5KM drive and then idle before engine kill.

Above is Idling



.
Conversion calculation




My Xentry ( other days ) when at only 60C coolant temp. Not HOT enough.




Mak wrote in blue ++1 : My reply in Green
Ok to answer your question about checking the camshaft and lifters when cylinder head was removed I can’t answer because was done by different person that I know and %100 was sent to mashing shop together with the cams and lifters to be checked and tested and the mashine shop was told that the engine misfires on #1 cylinder
When picked up from mashine shop the cylinder head they told my friend that they didn’t find anything wrong with it!
Just to let you know also I do this to learn and I like the challenge
No body wanted to touch this car anymore but I like the challenge and I took over maybe with your help I will get to the problem
I don’t know the long service history of the car but it looks good
No oil sludge!
But I think maybe cheap oil was used on the oil changes by looking at the oil change stickers on the windshield!

++2
Also when I let it idle for longer time and engine shakes and engine light blinks without turning the engine off and on take it for road test and in this case has no power!
That is ECM safety protocol killing injector and probably COP too, when misfire count is high enough to give the engine check light.
And I stop turn the engine off and start again and don’t let it idle just drive right away power is good!
NOTED


++3
Mak wrote :
its shaky when cold first start when warm not so shaky
Some times when I start the engine and drive right away I don’t let it idle at all it drives good,power is good and pick up is good feels smooth as soon as I let it idle it’s starts to shake and check engine light blinks.
NOTED


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

Now its your call,
AA - What do you want to do next ?
BB - What do you think is actually happening to your engine ? as per your own conclusion based on the data at hand ?
Chevota has given you input and so do I.


Your problem is tough because it is a dynamic one where it changes with changing condition ( RPM/LOAD ) as far as cylinder 1 investigation is concerned.
The comforting fact #1 is the leak down test is awesome result.
The comforting fact #2 : manual gauge compression test- good enough.
The comforting fact #3 is : Some times when I start the engine and drive right away I don’t let it idle at all it drives good,power is good and pick up is good feels smooth as soon as I let it idle it’s starts to shake and check engine light blinks.

When and if engine is loaded and it perform well but misfire only at idle ( low RPM ), this is a dynamic issue and is a comforting result/facts because we know mechanically it it wont be expensive to fix , surely not the
horrible kind of mechanical issue.

===========

If it is a dynamic issue, it has to be viewed in a dynamic way. But here we are discussing high $$ equipment for Pico scope 4425A and its required supporting accessories even when not all is from Pico.
US$3K-plus is on the horizon if you want to invest in more tools, but it can be used on all of your cars or friend/family cars. It is more like an asset.

If breathing of cylinder 1 is to be investigated ( assume injector at cylinder 1 is good and COP cylinder 1 is good too ) in actual running state, there is no other way than to pay or invest either in a techy/workshop with such equipment
or you DIY it and invest in the tools, that 2 of pressure transducers I speak of. But learning curve is another time frame to consider.
If a techy/workshop has the tools I speak of, 100% guaranteed he has the Ignition Waveform inductive sensor for COP too, as it is much cheaper.
In fact injector/s and COP/s all can be read with the same scope. So it is a one stop "shopping" for you when and if you can find a CAPABLE techy/workshop with all the mentioned tools.

I have the in-cylinder pressure transducer, China copy cat version of Pico WPS500 ( only US$250 or so ) and it is good enough, but its hoses fittings is garbage always leaking and I stop using it as I do not need it yet.
Go to AliExpress, look for : JH APT-100
See in youtube the reviews using search word JH APT-100
Dave Sterl channel is a better video to see as he is very knowledgeable and has many such toys.

I do not have the Delta Pressure Sensor yet, but this is low cost.....but must buy from abroad.


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


Let say you decide to believe my hypothesis, that the hydraulic valve lifters at cylinder 1 are the likely culprit and it was not inspected properly at the machine shop.
Per bank, the fuel injector seal set is each US$32, so 3 set.
Special tools you need. I have the list as I may need to buy them too next year.

Google more for the US$300ish DRIFT tool, you can get lower price a bit from official MB dealer in USA.




So, US$500 approx with sealant. But you get 2 special tools to keep.

Depending on if you can remove camshaft without removing sprocket, if you need to remove VVT sprocket for easier work, you need the camshaft locking tools. It is cheap.
China made one is OK. I have one from China.
You can buy in Amazon :

The hydraulic lifter itself is cheap at US$16 each, assume you need 4.
https://www.mbpartsexpress.com/oem-p...ers-6420500080


Its your call...............

S-Prihadi

Damn I forgot something.
If your cylinder head been removed and re-installed, I am certain he/they have installed new fuel injectors COMPLETE seals.
You can pull the whole fuel rail out ( with 3 injectors ) and probably no need to replace the injector tip seals and C* clip ( *supposedly one time use ) again as they are still "new".
Save you lots of money and time.




This is how the DRIFT tool for the injector is supposed to work for the upper seals and circlip etc

S-Prihadi

Gee, I thought you would know better with your engine tuning experience.
Valve overlap is also called scavenging and it is there at idle on "normal" engine.

I shall give a better visualization for you.

Below image from : https://www.researchgate.net/publica...ation_Software





Green circle the over lap /scavenging.
.




.
This video has a decent "moving" visualization




.
One is expanding view, one is shrinking view same thing




.

MakUsa

Question:
If the lifter is collapsing should he make any noise or tick?

S-Prihadi

If the collapse is loose as such there is much clearance between A to B, it would tick.
If the "collapse" is actually a VERY SOFT hydraulic lifter but A to B is still touching, probably no ticking.

If this kind of lifter below, surely it will take a ticking sound if it is not touching camshaft , as it is direct to CAMshaft and not via roller cam follower.



That's my theory

MakUsa

Got it ✅

MakUsa

I greatly appreciate your support and help with diagnosing this issue guys
i gather all the information and knowledge from you guys!
I made my decision to replace the hydraulic lifters and rocker arms on cylinder #1!
I will do the job this Saturday if I can get the parts by then.
I will post the outcome as soon as I am done with the job!
I think they should rank you guys Mercedes gods instead of fanatics 👏

S-Prihadi

Good luck with the work and do not drop the 2 bolts of timing chain tensioner or the tensioner into lower timing chain cover....surely you need to remove the timing chain tensioner.

MakUsa

Questions:
Do I need to remove both sides valve covers?
Or only bank 1valve cover?
Should I replace all 12 lifters on bank 1?(they are cheap)!
Should I replace the rocker arms also?
Obviously I need to remove both camshafts on bank 1 right?

S-Prihadi

This is the valve cover you speak of right ? I am assuming this is it.






Or you mean cylinder head valve cover ? below.......... If you meant below, yes, also only Bank 1's need to be removed. This thing is also bearing surface /journal of the camshaft.
So be gentle with it.





.
This is your engine camshaft removal. Please don't forget to mark with color paint pen the timing chain to at least 1 VVT sprocket tooth and if possible the camshaft tone wheel too.


While you have access to camshaft, check for the tone wheels are not shifted from the camshaft itself. It is only pressed and not spot welded as extra anti-shift.
There is a thin alignment laser line between camshaft tone wheel to camshaft .

See video below :


.
You must also look at all the camshaft lobes and make sure no obvious heavy wear or flat area.


.
.
Take your time and use the MB WIS to assist you.
You should have EPC/WIS too I am sure.

The HP Fuel Pump : you must be-careful when installing it and also when removing it. If during removal, loosen each screw 1/2 turn maximum at a time. So that the lifting up of HPFP which will
be under heavy spring tension, will be nice equal and slow. For installing it is the same, but you spin your main pulley to get fuel lobe of camshaft to be at lowest bottom, even better to work.
Your camshaft is a 3 lobe one for HPFP .
Here is HPFP fuel pump install-removal : https://mbworld.org/forums/e-class-w...l-warning.html


If you have not already replaced these PCV component or it shows worn out seal size ,and you must remove it anyway : You should replace them because these when worn will send lots of oil into intake manifold.
Item 30 and Item 80 to be replaced.



.
Item 30 seal wear comparison to a new one





======
When your remove the camshaft later, I will in separate post/request for you to do some measurement if you do not mind.
This measurement will help M276 3.5NA engine owners to get the zero degree of HPFP 3 lobes in respect to camshaft zero degrees.
I will let you know what is needed to be measured. Thank you.
======


Do it slowly and take your time, do not rush.
Observe the components you removed, so you get to know it better.


This one shows HPFP and PCV removal



Later............