SouthSideBenz

About 2 days ago coming home from work late at night, I put my foot down to the floor getting on the highway, but did not feel the usual kick back or acceleration. Immediately after I was greeted with a check engine light, got home and it read P0308 Cylinder 8 misfiring. Ive since cleared the codes, swapped coils, bought new plugs, cleaned out the air intake. But every time I rev over 4k or shift under a load, the same code "Cylinder 8 misfire" keeps popping up. This is the M113 engine with 2 spark plugs per cylinder. Has this happened to anyone else before? Could it be the fuel injectors, or MAF?

kajtek1

Bad MAF would give you several misfires, coil swapping eliminate that probability.
All you have left to check is injector.

cmriv

swap plug wires.

homeofstone

I have same problem on cyl 8 , 2005 E500. Did the following: new plugs, swapped plugs, swapped plug wires, new coil, swapped coils, Techron in gas several times, new injector. and with all this the problem was not fixed. So, if anyone has a suggestion as to what it may be please let us know. I have found no answer online. And BTW my engine runs excellent otherwise.

HarryCo4

Hi everyone! I’m having a very similar problem and I’ve tried everything minus replacing the fuel injector. It only happens on cylinder 3.

Any info would be greatly appreciated!!

Thanks,
Cody

CHIMECHONGA

CYLINDER 3 SEEMS TO BE A "B"...
I HAVE SAME ISSUE WITH CYLINDER 3, AND HAVE REPLACED EVERYTHING, INCLUDIN A NEW INTAKE MANI...NEW MAF,...NEW PLUGS...NEW COILS....I EVEN DE-CARBONIZED AS BEST I COULD..
STILL, CYLINDER 3 SEEMS STUCK, FOR LACK OF BETTER WORDS...

I EVEN CLEANED AND SWAPPED THE FUEL INJECTORS, AT THE RAIL, JUST TO SEE IF IT STAYED ON CYLINDER 3 (MISFIRE) AND IT DID...

OH, FORGOT TO MENTION TOO, LOOSENED EXHAUST MANI TO R/O CAT...NO DIFFERENCE...

I DO GET CYLINDER 2 MISFIRE 2, SO, OF COURSE THE P0300 TOO, THOUGH I THINK ITS COMPENSATORY, AS THE PLUG WHEN PULLED IS CLEAN...

I PULL NO CODES FOR CAMSHAFTS OR CRANKSHAFT SENSORS....BUT, WAS THINKING OF TRYING THAT, AS A LAST DITCH EFFORT..


I AM ABOUT READY TO PARK WITH AN "AS IS" FOR SALE SIGN....CUZ, QUITE HONESTLY, I AM TIRED OF THIS B.S. KEEPING ME UP AT NIGHT!

johnflight1

I have the same problem on my M113 eng on #3 cyl. when I accelerate and hit 4000 rpm the check engine light comes on every time without fail. when I reset the code it runs super smooth . I have replaced everything!
plugs, coil, and wires multiple times
MAF
Fuel pump, and filter
Crank pos sensor, and connector, and wire harness
Intake manifold gaskets, and all vacuum hoses, maf gaskets, slide gasket
compression checks good, cyl leak down good, no air leaks
exhaust back pressure good
Vacuum 16" at 3000' altitude
ohm all coil wiring grd and to computer
rpl EGR valve and smoked manifold no smoke leaks
also endoscoped cyl 3 looks good
I am thinking this may be some kind of electronic gremlin because it runs great till you hit 4000 RPM under a load any suggestions would help. Thanx.............

johnflight1

oh yes by the way its in a 2006 W220 with 134,000 miles and I have replaced fuel injector and all seals

marcd7tx

Had very similar issue on my 2005 W211 E500 with around 150k on the clock when it happened. Turned out to be a bad catalytic converter on one side of all things. Replaced it and it has run like a dream ever since. Got misfire codes and I had recently replaced plugs, and done similar things you guys had done so was very puzzled. Put it on a lift or up on ramps and tap the cat. Or at idle you may be able to hear it rattle.

HarryCo4

Hi John!

Yes, I did! I searched and searched for the issue and couldn’t find it. I took it to the dealer and they couldn’t figure it out. They tried everything. They scheduled me to come back when the head mechanic was there but it turns out somehow one of the things they reset with STAR unintentionally fixed it. I had tried everything with my little icarsoft. It is likely a computer malfunction that they will have to reset. Hope this help!!

Cody Cameron

johnflight1

I checked the back pressure of the exhaust at the fwd o2 sensor port and it was good , But maybe at higher rpm it clogs up if there is loose stuff in there . I will get under there with a hammer and check them out Thanx

johnflight1

So I put the car up and beat on all the cat's with a rubber mallet and I heard nothing loose in there ........I was almost hoping for it to be bad to put this to rest!! Any suggestions would be appreciated

Adrian052

Did you figure this out? I am having the same issue, and will likely find a aftermarket Cat put on at the primary passenger side to see if it fixes the issue.

johnflight1

No I have not! I just make an effort to keep it under 4000 RPM and then it runs great. Before you start changing Cats check the exhaust back pressure first . I made a tool out of one of my old O2 sensors and a vacuum gauge that has pressure also. pressure should be well under 1 PSI mine was about .5 or a half of 1 psi . Also get a rubber mallet and bang on them to check for loose material in the exhaust this would indicate a cat is falling apart .

tbb_87

Just had the same issue on my 05 E55
Misfire on cyl 8, swapped coils/plus/wires. Misfire stayed on cyl 8. Checked compression, was low. Camera to the bore revealed scored cylinder wall.
Not sure how that happened, I heard oil pumps go back and don't feed cyl 8 enough... time for a new engine.

SkywardOne

Just started to have the same issue with cylinder 3. I was going to start changing plugs and wires before I read this. What is the STAR update? I wan't to know all my options before I start throwing money at this thing. Thanks for everyone's input! I love my 500 Cab, more importantly the wife loves it too! Kangz.

johnflight1

on all of these posts on the M113 engine it is always #3 or #8 cyl missfire

johnflight1

I still have the problem. A couple of days ago I went thru the Injector and Coil to the ECU wire harness. It looks like a wire problem which has now gotten worse, the CEL comes on sooner than 4000 rpm when engine is cold and also runs rough when engine is cold. I think it is like this because I messed with the troublesome wiring. I also opened up the ECU and looked for burn spots on the board also for loose connectors,But it looks good as well as the wiring which ohm's out ok. Next I will replace the connector to the coil along with wire pins and maybe if I feel ambitious I can run a couple of wires.

Cameron Scott

Hi noticed this is an active thread - mine has misfire in cyl 6
im going to try replacing ignition coils and spark plugs in that cylinder.

johnflight1

Check out the Thread Misfire under load (high Rpm) in The CLK W209 forum It explains how the coils work above 4000 RPM with a load. Good reading

Adrian052

did you ever figure it out?

johnflight1

No Not yet, car runs fine as long as I keep it under 4000 RPM. I have the the new coil electrical connector now. I will try to replace it this week if the weather cools enough. It should go down to 107 later this week.

Kelvin Bellrose

I am thinking of purchasing a 2006 E500, wonder if this is a very common problem. I've got a 2007 CLK550 with a funky idle and low compression on one cyl. I am starting to think it may be a head gasket because oil samples show slight coolant leak into the oil.

johnflight1

The 2007 CLK 550 has the M273 engine the 2006 is a M113 engine in the E500. There should never be any coolant in the oil or oil in the coolant! Take the cap off the coolant tank and see if there is any tan or brownish residue under the cap. This would be an indication of oil in the coolant. Any Codes? Check Engine Light? I have a CLK 55 AMG 2002 runs like a top never had a problem with that M113 but my W220 with the M113 2006 is a disaster with the #3 misfire. When you pull the plugs on your CLK you will see the fouled plug on the cylinder with low compression.

Kelvin Bellrose

No sign of oil in coolant tank, nice and clean. No froth under the oil cap. No codes. No CEL. Just a lumpy idle. Once you step on it it will drive off smoothly.
It's not bad enough to rip it apart. I have changed coils plugs, cam solenoids, (I was getting a code for the cam solenoids). Nothing has had any effect. Plugs that came out were nice and clean. Changed them anyway.
I just drive it. It never seems to get any worse, but sometimes it is less noticeable.