I think that MAYBE we are missing Ockham's Razor here. Some years ago a buddy put on new turbos and pipes (3000GT). Everything was good, he was making it "gooder". Weeks went by trouble shooting. Well, one of the new pipes had packing materials in it....

A misfire (unless I am nuts) is not just no spark, it is improper ignition.

 

Or improper combustion, without fuel the spark can't move the cylinder and with too much fuel the spark is extinguished and again misfire...absolutely the same with the air, no air no fire, too much air the fire goes out.

Need compression ( air), spark and fuel.

 

This would lead me to think bad part. Say the flaps in the new intake were not opening properly.

This job is my next "big" thing for my E350. Looking over and over again at options I was going to go the FCP Euro part as it is everything (in theory) ready to bolt on and run. My only current "symptom" is a CEL for intake runner flaps.....can not say I can tell even slightly when I am in that car.

 

Sister's W211 with an M272 engine has the CEL for the intake flap runner. I verified that the actuator at the front of the intake manifold is broken. The engine idles smooth as butter; I have never seen a misfire reported for that car. However, as you accelerate, you can tell it is missing some torque until it gets going.

 

I also do not get misfires. Then again, I also have not replaced the manifold and THEN get a misfire. Seems to me the odd thing out is this new part.

 

.

 

Thank you for your reply. Anything is possible at this point.

The flaps all act in unison across the cylinders in each bank. A failure here would affect cylinders 1/2/3 or 4/5/6 at the same time. This is happening on cylinders 1 and 4.

Can you think of a manifold failure condition that would take out only cylinders 1 and 4?

 

Thank you for your reply.

I read that document. Does the ECU start injecting again once the error codes are cleared? Is it possible that the flaps are bad and a maximum of two cylinders are being turned off where it would shut all of them off?

It is cylinders 1 and 4 every time and the rough running happens right away. If the flaps got stuck in a bad position when I gave it the beans then that would explain it.

1. I have not heard of LTFT before so I googled that. I believe my icarsoft mercedes device can query these.
2. What constitutes a reboot? I had the ECU disconnected for a few days while I took a break from this to clear the frustration.
3. Before the first startup after getting it all back together, I cleared all the chassis faults with the icarsoft mercedes device. There were many.
4. I'm off to get a fuel pressure gauge. Would an issue with fuel pressure affect more than one cylinder? Cylinder 4 is closer than Cylinder 2 to the fuel line if borderline low fuel pressure is the issue.
5. What do comparing these numbers tell me?

 

I bought a pierburg, installed it, and the exact same issue is occurring.

 

The problem is still occurring. When the issue started it was sometimes cylinder-1 and sometimes cylinder-4. The last time I gave it full throttle cylinders 1 and 4 both showed a misfire and haven't come back since.

Troubleshooting so far that has not changed the problem: (latest at the top)

• Cleared errors on all systems before each test (some permanent codes remain)
• Bought and installed a Pierburg manifold @OldManAndHisCar and there definitely is not any packing material in there
• Replaced the two vacuum lines to the manifold
• Swapped spark plugs - cylinder 1 with 2, cylinder 4 with 5. - spark plugs looked fine
• Tested all six injectors with an injector tester, reinstalled with new seals.
• Replaced all six coil packs with OEM Delphi
• Checked continuity between the ECU connector and both cyl1 and cyl4 coil packs
• Checked contiunity between the three non-ECU cyl1 and cyl2 coil pack connections. Same between cyl4 and cyl5
• Ensured that the ground on each side is clean and tight

Next to try: (I'm open to ideas)

• Check for spark with a spark indicator tool (arrives in a couple of days)
• buy a replacement wire harness off of ebay for $100-150

@CaliBenzDriver I have had the ECU disconnected from battery for days and I cleared the codes before starting. What does comparing the LTFT indicate?

 

LTFT will tell you how engine combustion are running:
rich or lean.
From there you goes towards whats related.
Misfiring is usually a lean... unless it's the ECU disabling cylinders.

 

The best way to troubleshoot misfire will be using scope.

Lets use 2 channel scope , with common ground.

01. Make sure ECM send the 5 volt trigger signal to COP. - Need scope. Channel A or 1st channel. Lets call this 5V trigger as #1
Scope positive lead to pin 4 of COP ( 5V trigger from ECM ) and scope negative lead to pin 2 of COP, that is its negative from W16/5.


02. To confirm COP is doing the firing, upon receiving the 5V trigger signal..
This one you need a scope, channel B or channel 2, with current clamp* ( *for scope use ) reading power consumption of the COP. Let's call this #2D
3 COP shares 1 fuse. Fuse 23 at Font SAM, is for COP cylinder 1, 2 and 3rd.
Fuse 24 is for COP 4, 5 and 6th cylinder.
With special fuse jumper wire, you can read all 6 COP from 2 fuses using 1 single current clamp.

This is a minimum set up.
Best also to get the COP secondary ignition waveform sensor/probe. Induction sensor.
So you can see how the spark plug ( also COP ) is firing.


COP cylinder 4, 5 and 6


.



.



.




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


COP cylinder 1, 2 and 3

.


.


.






==========


For the load test reading fuse 23 and 24, use this type of fused loop wire : https://www.aeswave.com/Fuse-Buddy-C...Kit-p9710.html
Or you can make yourself using simple fuse holder and suitable male terminal similar to ATO fuse blade male terminal, like below sample from M271.8 EVO engine.

One word of caution. Front SAM fuse block female terminal is design to accept thin blade fuse, thus when using male terminal in lieu of fuse blade, do not use too thick
a male terminal blade which can "open" up the front SAM female terminal for the fuse and make loose grip.

Above was in 2021, where I only have 2 channel Pico scope non automotive, this one : https://www.picotech.com/oscilloscop...-2000-overview
I was then using model 2205A , 25Mhz memory only 16Ks. This is 8 bit scope, so resolution is not too good if for CRANKSHAFT waveform.
Good to start with this, very cheap.


=========


The scope capture will be like below, this is my engine M276.820.. This one I am using PicoScope 4 channel automotive, the 4425A with floating ground.
https://www.picoauto.com/products/au...ew?model=4425A
This one is very high resolution 12 bit and good memory size.

The 5V trigger ( red channel B ) is sent to COP at duration of 877 microsecond. ( 1,000 micro second is 1 millisecond. 1,000 millisecond is 1 second )
The COP then ramps up to 18.9 amps ( Green Channel C ) ) and release its energy, that is when the spark flies. The amperage ramping up is for the primary coil inside the COP.
Thus a scope is needed, you can't use DMM to see this kind of speedy signal.






You can then inspect how the amperage ramp is for the COP and how is the 5V trigger from the ECM ?
If these two are OK, you can get this low cost 6 cylinder in 1 channel COP induction sensor from Rotkee, to see the secondary ignition waveform.
https://store.rotkee.com/en/lx6-coil-on-plug-probe.html <<<----This is so good for its resolution and so cheap, I love it !!!!
Above unit, 6 cylinders COP induction sensor using 1 scope channel only. Its price is LOWER than US/UK branded COP sensor of 1 channel !!
Typical COP inductive sensor, 1 channel of scope for it :
https://www.aeswave.com/COP-Secondar...ive-p9151.html
https://www.aeswave.com/COP-probe-p9335.html
https://www.aeswave.com/eCOP-II-Igni...up-p10154.html


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

Example of M272, member Tesna engine. Secondary Ignition waveform using Rotkee 6 cylinders COP probe/sensor.




.








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


M271.8 Case Study. 1.8L Turbocharged 4 cylinder gasoline. Found on E200/E250 W212 and C200/C250 W204

This engine is still using dummy COP, where the power is from ECM and not from built-in driver inside the COP like your M272, and direct fuse from Front SAM.
So dumb COP burden the ECM with the 10ish amps of COP power, thus its driven in the ECM often burnt out, example is the ME9.7 ECU.

Red signal (channel B) is the voltage into the primary coil of COP. Thus it is low voltage, only 30-40 volts.
Blue signal (channel A) is the power as in amperage consumption read at the fuse, at front SAM for all 4 COPs. This one using current clamp.
See COP cylinder 1 is weak at 2.5 amps from usual 10ish amps, thus engine has misfire. At times up to 2 COPs goes bad.
The culprit here is the ECM itself.




The M271.8 EVO engine was a learning process for me both first time exposure to an MB ECM and first time use of the 2 channel picoscope 2205A.
I wasted time from one dumb azz mistake. This M271.8 COP is a 3 wire coil, I thought it is smart COP like M272/M276/M278.
It so happened the 3rd wire is another ground wire and not 3 wire type smart COP
If two wire only COP, that is 100% guaranteed dumb COP.


The key is looking at this transistor symbol for "smart" COP.





Ok good luck...........

Find attached Port Fuel Injection Type M272 ECM wiring

 

Sharing..........

M276.820 3.0 Turbo COP and M272 3.5NA

There are two grounds on my COP.
Pin 2 is the real power (-) ground
Pin 1 is signal ground back to ECM ground , it is called W11
If pin 1 get disconnected, a mild misfire will happen, very mild, for my engine.






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



If M272, as per : pe07.61-p-2101-97dae,
Wiring diagram for ME-SFI (ME) gasoline injection and ignition system control unit. Engine 272 in model 212 Control unit N3/10, engine connector

Pin 2 is the real power (-) ground
Pin 3 seems to be the signal ground back to ECM ground, but its to engine metal ( cylinder head near manifold ).






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

I think if power to COP is a suspect, at the least you must load test the negative power for your ECM.
It is the elusive W16/5. I say elusive because to date I believed I have not seen anyone here documented cleaning their W16/5 for a US Left Hand Drive car.
Cali has pointed out its location .
I discussed it here : https://mbworld.org/forums/e-class-w...6-9-3-5na.html

My car is Right Hand Drive, so the what is brake booster for LHD car is remove-able battery bay for my RHD car, and I can access W16/5.

NOTE : Above is F connector. See small F on the very top left.

----



You can load test W16/5 via the ECM wire harness side connector, which is a more honest test with wire included
No need to find its ground stud behind the brake booster.
Use 100 watts bulb if you can or 2 of 50 watts. Pin 2 and 4 get each 50 watts, DMM on pin 6, or whatever way you like. Be gentle on these female terminals/pins.

The W61/5 pins 2,4 and 6 at F connector of the ECM you won't missed its fat size SLK2.8 female connector.
This is my ECU wire harness side connector F, it will be very very similar connector to yours I am sure.






Happy troubleshooting.

 

@S-Prihadi Thank you for that detailed troubleshooting step. I'm not familiar with using a scope so that level of troubleshooting is out of my league.

At this point I'm going to have to take it to a specialist that can use a scope to troubleshoot.

 

@S-Prihadi My last effort is to test the grounds per your last message. Past that I'm going to have to find a local specialist and limp the car there.
How do you do a load test? Do I run a wire from the positive of the battery to a 100W bulb and then connect the other side of the bulb to pins 4 and six? What kind of bulb? A household 100W bulb?

Question: I'm using an iCarSoft https://www.icarsoft.com/Product/s-408-cr_v3_0.html to clear the codes. I have the Mercedes software on it. It scans for all the modules and shows trouble codes.
Is there a chance that this code reader is not fully clearing the codes so the ECU is still not usring the cylinders? I run a new scan after clearing the codes and nothing shows up until I start the engine and experience the misfire.

So I fired the parts cannon at it a few times.

• I replaced the MAF.
• I replaced the engine wiring harness with a used one from eBay (identical part numbers)
• I swapped coil packs (1 with 2, 4 with 5) one more time to be sure it isn't the coil packs.
• I swapped spark plugs (1 with 2, 4 with 5)
• The two vacuum hoses to the front of the manifold are new
• Previous steps
  • Replaced all coil packs
  • Bought a Pierburg intake manifold
  • I have removed/reinstalled a manifold several times now

Cylinders 1 and 4 are still showing a misfire, but with a difference in fault codes.

Additional "primary control circuit/open" cylinder 1+4 error messages showed up. I had seen these before.

I believed I caused them when I was disconnecting and connecting the coil packs while the engine was running. In this round of troubleshooting I have kept all coils connected while the engine is running.

Here are the current codes
P0300 Random/Multiple Cylinder Misfire Detected
P0301 Cylinder 1 Misfire Detected
P0304 Cylinder 4 Misfire Detected
P0351 Ignition Coil A Primary Control Circuit/Open
P0354 Ignition Coil D Primary Control Circuit/Open

Next steps:

1. load test the grounds
2. inspect the ECU pins
3. RKW IR IN RO apwxiLIAR.

 

if everything else has been changed perhaps its the ECU

 

Makes no sense as the manifold was replaced prophylactically for symptoms outside of the current things - and with a running engine. .

 

I do not see a compression test, nor a leakdown test. A burnt valve will cause a misfire.

 

Load it using 12V 50 watts x 2 units, halogen bulb. If you have other car not using LED headlight and Xenon, it would be halogen bulb for sure.
Or you can get this type : This is a VERY hot bulb and you need to buy the ceramic base-connector for it.

This is how to do load test for the pin 2, 4 and 6 of ECU wired connector side, which these 3 are from W16/5 ground stud.



iCarsoft V3.0 should be able to clear properly DTCs.
Me only have the older one MB v2.0 and stop using it many years ago.

 

That is exactly what is driving me crazy!

 

The engine was running fine before the manifold replacement. There wasn't a misfire until I did the manifold replacement. As far as I know I didn't damage the rings or valves in two cylinders.
I can try to do a compression test on a cold engine.

 

[QUOTE=S-Prihadi;9076245]Load it using 12V 50 watts x 2 units, halogen bulb. If you have other car not using LED headlight and Xenon, it would be halogen bulb for sure.

I have a pair of 55W halogen bulbs that I can use.

I read your posts a few times. Thank you so much! I am still trying to understand the purpose of the of the DMM on pin #2.

If I'm reading this correctly, all three pins 2, 4, and 6 connect to W16/5 so I should load test each of the three. Is that correct?

I have a digital clamp multimeter if reading the current will help diagnose the issue.

 

With the same issue occuring after the harness replacement I'm starting to wonder about that part.

I wish it was easy to try another ECU to see if this is the case. A quick forum search tells me that I would need a new ECU and someone would have to clone my old ECU onto it.

 

[QUOTE=RWagz;9076536]The 3 wires from pin 2, 4 and 6, by wiring diagram are all connected to the same W16/5 ground stud but they are indeed supposedly 3 separate wires with each having its own circular connector/terminal.
Yes you can test all 3 pins using the two 55 watts bub , 2 pins at a time and you can place your DMM at any of the 3 pins you want .....be it the one with or without the bulb. Pins with bulb will have more
voltage drop. Test as complete as you can will be good, just in case 1 wire is bad.

 

[QUOTE=S-Prihadi;9076589]I let it sit for a while so the battery was low. I had it on a charger when I did the test.

All three measured 11.46V where one without a bulb tested at 11.53V.

I got some contact cleaner and ensured that the pins and sockets were clean/clear. Still no luck.

My next step is to send in the ECU to be cloned. Thankfully I have an extra car so I can be down a car for a long time.