ITech

I've got a bad misfire in cylinder 8 and I think I have narrowed it down to the coil pack. Going to swap that coil into another cylinder and see if the problem follows. Has anyone else experienced a random misfire that just appeared out of the blue? it goes away after I clear the CEL but comes back within 5mins. When I hooked up my scan tool I noticed that one of the MAF's is showing a flow rate while the car is off (Maybe explaining why the car runs so rich all the time ) If anyone has had this happen id love to know how things turned out for you!

EDIT: Wrong Section Sorry!

DrDoe

I just had misfired on #4 couples day ago. Background, misfired came and go on my ML63 a few times and I didn't bother to look up the codes. Spark plugs were replaced 20000 miles ago.
Couple days ago, CEL came and stay and the car has no power. P0304 came up so I swapped #1 coil with #4 coil. Before placing #1 coil on cylinder #4, I placed some dielectric grease on both coil springs. No more engine shaking and no more CEL after the swaps so I guess the problem was just contact issue.

ITech

Going to give that a go in a day or two once I get a chance. Fingers crossed that is the issue!

IgorE350

Yeah id start from coil pack. I had that happen on my W163 a lot. Switch and see what happens. and wile you doing that clean your mass airflow sensor. and if you have a lot of miles id do spark plugs.Good luck!

ITech

Swapped coils and still Cylinder #8 misfire I did get a fuel injector error for cylinder 8. I'm going to run fresh cables from the injector to the ECU tomorrow because this car has had issues with this side of the harness as it stupidly goes under the intake manifold and gets munted. Also got a code for the bank 2 knock sensor which also leads me to believe the wiring is bad. I hope this fixes the issue otherwise I'm taking it to a local indie shop that will charge 100's for diagnosis and fix.

Maj. Dundee

Please read #7.

ITech

I don't have access to STAR DIAGNOSIS. Is there a way to test the ignition system without it?

Maj. Dundee

What #7 says is that there are 3 possibilities for misfires:

Misfires caused by ignition system faults

Misfiring through fuel starvation

Misfiring because of miscellaneous causes

ITech

Taken the car down to the local indyshop and they believe that the manifold is cracked. I’ve not had a chance to take a look myself yet but I don’t believe that it’s the issue. My manifold does have a small crack where the fuel rail connects above cylinder #5 which would not cause cylinder #8 to misfire? The issue also seems to be intermittent as ive managed to drive for 20mins no issues and other times it misfires right from the get go. Personally I believe the issue lies in the O2 sensors as I have a circuit error code for the second bank but my mechanic claims to not understand the output from my OBD scanner

The Indy doesn’t want to take off the manifold without me there as he claims it will crack completely. I’m going to get them to check those darn O2 sensors tomorrow before I head down.

I’ll keep this thread updated as I get some more info.

Maj. Dundee

The Intake Man. is an intricate component. Being that 5 and 8 are on the same side, there is a strong possibility that one of the flaps is faulty.

ITech

The crack I have is the same as the one in this thread so I doubt its actually causing any leaks or issues. I've made a Pastebin with my most recent scan and the P0155 code means my O2 sensor is more than likely kaput. The P0661 code would worry me but it's on the wrong bank so I don't believe that would be causing me an issue with cylinder #8. The PDF you attached is for a different engine but I'm sure the same principles apply however I do believe that the manifold on the M156 can be disassembled.

Maj. Dundee

Nothing satisfies you.

ITech

just trying to make a Informative thread with my experience so if someone down the line has a similar issue they have a place to get some information. There is nothing more useful than personal experience