Frank Castle

OK Check engine came on when I gave it a little gas Friday. Code was Misfire. I assumed the gasket was leaking some oil in the plugs and fixed it. Car drove great for a day.

I gunned it on the highway and the engine light came back on, and has gotten increasingly worse. Same code of Random cylinders. I recently put in MB sparkplugs. No oil leaking in them.

Now it will just pop code even without putting it in drive. It'll close down power to about 20 mph max.

SO next suspect was the over due coil wires. Only 10 of the 16 came in from UPS. They vary in length. I wanted to re-do the side I just worked on and used 9 shorter wires. The code was reset and is still an issue. (If the wire will reach its not a major issue is it??)

PCV valve had a crack but would that really cause an issue like this?

What to do with this Love Hate relationship. Anyone have similar issue?

grane

https://mbworld.org/forums/mercedes-...g-running.html

Hope this helps.

Frank Castle

Starts fine. Idle will be slower than normal but cranks over with no effort. That is weird though. I have been filling up in PA with gas as its cheaper than MD. Bad gas could do this? I always use high test.

Frank Castle

So 4 more coil wires came in and same results. So I was pushed into swapping wire that it probably needed anyway.

Mas Airflow Sensor being next suspect? I tapped lightly 3x on the MAF Sensor light with 3 fingers over the top to see if anything would change in idle. It stalled out. I was able to repeat the failure. I am not covering the hole over depriving it of air. Just a tap 1-2-3 and it cuts out. NO MAF code is showing on the OB2 reader I have . Just P0300 code (random) and every once in a while narrows down what cylinder misfired.

importfan21

You sure it's not plugs? I had a similar problem a while back and swore up and down that the plugs were fine when I looked at them. Replaced the plugs and the problem went away.

Frank Castle

I had replaced the plugs with MB brand plugs a few months ago. It was running great.

Frank Castle

Not plugs, not coil wires.

Cleaned the MAF sensor, no change. Ran some codes on it and Cylinder 2 and 7 were a constant of the random misfires. Others do code but 2 and 7 are main ones. I swapped coil packs and got the same results so its not coil packs.

Mechanic says bad gas would had caused all cylinders to go goofy.

Running a smoke test and compression test next. Any advice here?

503C43 ////AMG

Replace the MAF

Frank Castle

OK great- No throttle response. Hit the gas and no response at all. Idle seems better but zero response with pedal.

WTF

Frank Castle

Well looks like the new throttle response took me into a new search, that may have led me back to my answer. MAF, just hope its right.

http://www.benzworld.org/forums/w163...esponse-2.html

grane

https://mbworld.org/forums/m275-v12-...misfiring.html

Frank Castle

Well I erased code with OBII reader. Throttle is back. Added a MAF sensor...no change. It was used off a ML500 so the pain of being wrong wasn't as hard.

Grane its almost empty, I will be adding shell 93 into it. I always run the high test but admit I did fill up in PA "sheets" gas stations quit a few times prior to this.

Wouldn't the CAT converter pop a code if it were the issue? Gonna try taking out a 02 sensor and see if the bong hole chamber will help. If not I am gonna need a bong to get through this....I keed, I keed.

hhughes1

If the misfires are specifically on one cylinder bank then you most likely have an O2 sensor issue. I had an issue that took three weeks to figure out because there was not a specific O2 code being thrown, just misfire codes 301,303,304. Once we replaced the front sensor car was fine.

Frank Castle

Thanks Hhughes1- By banks I take it you mean sides of the car? Its been doing it on all cyl. 2 and 7 were constant hitters, but yes the Drivers side does have more hits (misfires) when I let it run to see what it grows into. So...maybe more than one O2?

Wouldn't the codes for a bad o2 sensor come up somewhere???

Is there a way to test em vs keep throwing money at it? I'd be all for replacing em all if i knew it was it.

Frank Castle

Today I took a temperature gun to the cat. One was running 100+ degrees hotter than the other car. I pulled out an 02 sensor and it did allow for a (tiny bit) more throttle. So at this point its directing back towards clogged cat(s).

Unfortunately my car is 7 yrs shy of being allowed to go straight pipe in my state. I guess I could for now, but eventually have to replace them.

Has anyone drilled out their cats vs putting on straight pipes?

What is going to be an easier job (for the long run also)
A. Go straight pipe until emissions day. Then take on a Magnaflow type converter.
B. Drill out the cats. Then put in new cats when time comes.

I am looking to do this job fast as possible. Car has been down for to long at this point. I wish I knew of a shop that could just take care of it.

Any suggestions appreciated.

Saaboteur

Which cats are you referring to, the primaries or the secondaries? The secondaries are pretty easy to get to, but you'd have to cut them off the pipes to get at their innards. The primaries bolt up to the exhaust manifolds, and if I remember right, neither really have flanges to bolt or unbolt them further downstream.

I was quoted about $100 to straight pipe the two secondaries, which I think I will probably do in the fall - but we don't do emissions testing at all, so I can get away with just about anything. I think in your case, you should probably get new cats now and be done with it - otherwise you're gonna be going in there twice to cut and weld.

BTW, is your name really Frank or are you a big fan of the Punisher?

Frank Castle

Yea you got it.... Punisher fan

I am not sure if its called primary or secondary . I was hoping i could separate them, and split it apart enough to be able to get into it to hollow it out. I think your right...penny wise pound foolish. I will have to revisit the issue again. I really dont want to wait for the part to come in though.

I looked at Magnaflows site and C43 is not an option? It had C36...what gives? C36 same 3" pipes?

MarcusF

I've hollowed cats before. At high RPMs it'll run better with a new cat or straight pipe. Thats because the hollowed cat is a bigger low pressure zone than a functioning cat. Metal substrate cats will allow you to do the job once. Are you going to weld them (muffler shop) or slip fit them with clamps?

If the O2 sensors are the original parts, you may want to replace them. Unless the heater is dead, they throw a code long after they stop working.

Frank Castle

Thanks for the input. At this point i think I want to just replace cats vs revisiting the issue when inspection comes up. Penny wise- pound foolish comes to mind.

Magnaflow comes up with zero product for the cat
Summit racing came up with Magnaflow 9905HM for it. So.........?

CLK55 is the same? What year ranges sync up with the C43.

FUN FACT: Out of curiosity I have called around Meineke had quoted me $2k upon hearing Mercedes.

503C43 ////AMG

Call the dealership, $2k will sound like a STEAL!!!!

Frank Castle

Sure...

503, you had deleted your 2nd cats. Any issues with emissions or codes ?

Did you keep primary? I am looking for possible replacement cat and zero luck on here or the interetsss.

503C43 ////AMG

Who is 505???

I had my secondary cats removed and kept the primaries. I have had it like this for around a year with ZERO issues, no CELS, passed DEQ, and sounds NICE!!!

I plan on installing the kleemann headers which delete the primaries. I will be installing 300 cell metal cats where the secondaries were. As long as the O2 sensors are rerouted there should be no issues.

Frank Castle

503...dyslexia moment sorry.

Sounds like a nice set up. Unfortunately I have 7 yrs before i can kill the cats. Need a low cost solution.

503C43 ////AMG

Which cats are you trying to replace, primaries or secondaries?

Frank Castle

At this point I am not sure. I assume the primaries would be the suspect if clogged cats are causing issues. I admit defeat and need to take it into a shop. My expertise is null at this point. I cut bolts off 2nd cats yesterday in an attempt to drill em out. Glad time got to the best of me as i discovered they were only the 2nd cats. I need to narrow down the issue before throwing another gue$$ at it.