Not sure if I made a thread about it before, but here goes again. Ever since a burnout I did on the fourth of July, my car developed a running issue. It sounds like it is missing on a few cylinders, but a dead miss; not a misfire. First thing I did was a compression test. All cylinders were within 5% of each other, at about 145 PSI. What an instant relief that was to see.

Then I figured my CPS went out because the car just decided not to start one day. Replaced it following day, still nothing. After further diagnosing, found out fuel pumps and sending units went bad. Replaced those the next week, and the car was running again. But the miss was still present. STAR was showing cylinder faults that moved with moving the spark plugs and wires, but did not improve with new spark plugs. So it was narrowed down to wires.

Just the other day I figured I would try to get this problem resolved before my virtually brand new V12 Evos flat spotted permanently. Starting from scratch, it started up after adding some fresh gas and a battery replacement (other one dropped to .4 volts after sitting, so I just replaced it under warranty). Started right up, but the miss is still there. So rather then using STAR to diagnose I used my scanner with euro coverage (Snap on Solus Ultra) rather then bringing out the laptop and cables and multiplexer etc etc. I also wanted to use the euro coverage on the 211 for the first time too, so I figured why not. Now after trying to diagnose with data logging, the car does not want to start anymore. It sounds like it is trying to just fire up but it wont.

During data logging I found an odd feature called Ionic Current then a graph for each individual plug. Here's the pictures from the data logging, and then other categories I can explore. Can anyone help me get this damn issue fixed? My poor 211 hasn't been on the road since July 4th, and I want to take it out again before it gets cold and snowy out.


This is the information from running the car while logging the Ionic Current values for each plug. This is what I cant figure out. Any ideas?

Heres the codes that popped up while data logging. Internet searches showed that when this particular code appears on Mercedes, it usually is a plugged cat. TWC showed up as Three Way Converter in a search. So Would these codes mean a cat is plugged? I will confirm this weekend but unbolting exhaust from down pipes.

Thanks for any input! Hopefully I can get this resolved...

 

Pull your mid pipe off and start her up. If it is a clogged cat, it should run fine on open headers.

 

No other codes stored? What do your fuel trims look like? Could be fried cats so def try that. Have anyone that can measure wave forms and trigger signals? May want to check to see If you have a clean signal coming from the CPS and also verify your coils aren't starting to take a dump.

 

Even if clogged cat the engine should startup but have little power, maybe idle then stall as pressure increases in the exhaust. The Ionic readings look odd can you pull the wires off cyl 3 and 6 7 8 put old plugs on the wires and see if in fact you have spark when cranking the engine, 2 people required. Also do this to cyl 1 as it looks normal to check for spark intensity.

 

Have you checked the resistance of the wires? Have you swapped coil packs around?

As for the starting problem - toss the old CPS in...

 

Could be a possible wiring harness issue, a bad tune, or a faulty M.E. issue. I looked back at your old thread. Please list all of your mods. We need more info. The codes that you have that you showed pics of...these are not directing you to the catts...they are indicating that there are cattalyst damaging missfires. If im reading your post correctly, you have a STAR unit. connect the unit and go into M.E. and see if you have "smooth engine running"... this may be under actual values in the "at idle" section". this will let you see exactly what cylinders are missfiring. Do random cylinders missfire? do you have just one or two cylinders missfiring? Ive been an MB tech for 8 years and more than happy to help, but I need alot more info. PM me if youd like.

 

When trying to start it now, it fires a few times then quits. I will pull the exhaust Saturday to test further, and will test for spark tonight, as well as changing plugs and moving coil packs. Hopefully we can get this fixed!

 

Do you have any codes? I think your wasting your time pulling the exhaust right now. the exhaust would have to be completey plugged for it to cause a "crank no start" issue.

 

also... just a dumb though... are your air filters clogged up?? simple thing, but can cause some funny things to happen.

 

possbility that its been sitting so long that small animals have created a burrow/nest and clogged something up as suggested above?

 

^ This is something so simple, and its possible. . . . .
I had no codes, but a loss of power. It wasn't the MB, but an A4.
I went to just a tune up, and after the plugs and wires I went to do the air filter and found that a critter decided to make a nest in the air box.
Once cleaned out it ran great.
GL

 

verify spark, you state that the " STAR was showing cylinder faults that moved with moving the spark plugs and wires, but did not improve with new spark plugs." were you physically removing and reinstalling plugs and changing wires to different cylinders, or were you just moving stuff by hand??. By chance are they original coil packs and wires? You have to go step by step, spark, fuel, air, all three will make it run. As the Tech has said possible coil pack wiring, if you find a coil with no spark check it for power and ground.

 

Possible you sucked in a CTS-V!!, only if you have a pulley and tune though.

 

As the tech states do not pull the exhaust, you are on the wrong trail and will only compound the downtime.

 

*snicker*

 

Air filters weren't clogged, I tried starting it with open throttle body. Filters were just recharged too. And I was actually moving around the plugs and wires. Car has a new coil pack too, I thought that was the problem but it made no change.

 

Your not giving me any info to work off of. How many miles are on the car? What mods have been done? All I know is that you have a "crank no start" issue now. Do you have a good crankshaft position signal? Do you have fuel pressure? Is your throttle valve moving?
You need to follow the KISS method first (Keep It Simple Stupid). Check all of your basic things. You know you have compression... Make sure the air path is clear and the throttle valve is operating. Do you have fuel?? A faulty crank tensor will cause you to have fuel pressure, but the the injectors will not fire. Check it at the service port? If you have those, do you have ignition? I'm trying to help the best that I can... But your not givin me any info for me to help.

 

Cps is new, so there should be crank signal. There is fuel at the Schrader valve, with good pressure behind it, and the throttle valve sounds like it's moving when I press the accelerator pedal while KOEO. I'll test for spark here in a little bit and post back.

 

This is from the spark plug closest to the front end, on driver side bank. It tried to fire up once, but that was it.
Just click the black image to play the video. My driveway light was off and it was dark out but it helps make the spark tester visible.

 

When you did the video it looks as if you have intermittent spark, how did the others look , especially the # 6 or #7
As stated above replace the new CPS with the old one to see if the spark is constant, also check the inside of the connector to the CPS for anything out of the ordinary to ensure good contact, also look at the wiring for this.

 

+1. We worked on a dodge ram srt10 truck. They put a custom exhaust and rewired 02 sensors incorrectly. Messed up the cats and the truck ran super bad. 6 months later, 8k on parts and labor we find out its the cats.

TRY THIS FIRST!

 

I also took the throttle body off today and cleaned it. It was full of black gunk. I'll reinstall it and see where that gets me.

 

critter,liked the cts v comment ,reading and learning just in case

 

Tested the spark on cyl 6 and 7 and saw the same results as cyl 4. All spark was the same time apart. The car did try to fire up during testing, and the spark became more rapid, but momentarily. Then it quit and just kept cranking. I think I can make out a fuel smell in the exhaust too. So assuming there is air as well, wouldn't that be plugged cats? I am pretty sure there is fuel based on exhaust smell. So should I pull the exhaust next?

 

Sorry for my late response... I just saw the Pm you sent me. I wouldn't pull the exhaust just yet. Something seems funny if the spark was getting more rapid during your spark check. Have you thrown a computer on it yet to check your crank signal? Go into actual values and look at engine rpm and crank the engine.