I have a 02 clk 320 with 150,000 on it.im am getting misfire codes on the 4 and 6 cylinder,I have replaced the coil packs plugs and wires for those two cylinders and its still giving the codes for those cylinders.i am at a total loss,can you guys help me out with this please.

 

Welcome to the forum. Have you cleared the codes? If not, try that. If the codes reappear post the codes here.

 

the codes are p0304 and p0306

 

Do the codes reappear immediately after start-up? Any recent exhaust work? MAF cleaning?

 

after I clear the codes,the check engine light comes right back on,.i don't think any other work has been done to it,i just recently got the car on a trade 2 weeks ago,cant get in touch with previous owner,he want return my calls

 

as incredible can sound to anyone, i was having random misfire codes, some random hesitation, changed various things (coils, cables, etc..) and nothing solved, but one day at service the didn't have the oil they have been puting in the car, then i changed it to Valvoline Synpower Full Synthetic 5w40 and all my problems went away! the car runs soo smooth, no more codes, you can certanly try this my friend.. What oil have you' been puting in the car?

 

Well your problem seems ignition related but these issues can always seem like one thing and turn out to be something else. So I'll give you a few things to check. Obviously I would suspect you would want to do the cheapest thing first, so.. Check for vacuum leaks around the top of the motor (These old plastic lines are known to break over time and cause misfire codes), pull the plugs on those cylinders and check them. Now the options that could cost money.. MAF sensors are kind of an issue on these vehicles and there are plenty of threads here that can explain how to test/replace. The other thing that could possibly be the problem is a bad catalytic converter, quite possibly one on the same bank as the misfire. Hopefully this helps you out a little.

 

[QUOTE=MagmaRed55;6034032]Well your problem seems ignition related but these issues can always seem like one thing and turn out to be something else. So I'll give you a few things to check. Obviously I would suspect you would want to do the cheapest thing first, so.. Check for vacuum leaks around the top of the motor (These old plastic lines are known to break over time and cause misfire codes), pull the plugs on those cylinders and check them. Now the options that could cost money.. MAF sensors are kind of an issue on these vehicles and there are plenty of threads here that can explain how to test/replace. The other thing that could possibly be the problem is a bad catalytic converter, quite possibly one on the same bank as the misfire. Hopefully this helps you out a little.




ok,have to start somewhere,gonna take the car in today for an oil change
thank you for your time and help.im much grateful.

 

put Valvoline Synpower Full Synthetic 5w40 you won't regret.. or Mobil1 0w40 as mercedes recommend. That should be your ONLY options for these beautiful car.

 

It's your MAF...do a search...this has been discussed many times. There is a weakness w/MAF, CPS and seat motors with our cars. Other than that they seem bullet proof. All these misfire codes ultimately come back to a bad MAF...don't try to clean, it's a short fix...don't buy ebay MAF (junk from China..fail in a few months). Get a new one from autohauzaz...careful when installing the air filter cover when done. Insert it securely into the new MAF and gently lower towards front (2 clips hold down).

 

I ordered a new one today from the dealer......thank you for that info
should have it in a few days!!!!!!!!!!!!!!!!!!

 

changed the oil today,it lookedas though the previous owner never changed it,when I removed the old oil filter it just fell apart,it runs a whole lot better but its still throwing the mis fire codes.

 

what oil did you put in?

 

Valvoline synpower full synthetic 5w 40!!!!!!!!!!!!!!!!!!!

 

Have you replaced the MAF yet? Oil has nothing to do with your codes...somehow the original thread title "misfires" is getting confused with what kind of oil you are using.
Correct the code issue and the engine with smooth out...doubt the oil had anything to do with change in engine.

 

[QUOTE=cindyclk;6037916]Have you replaced the MAF yet? Oil has nothing to do with your codes...somehow the original thread title "misfires" is getting confused with what kind of oil you are using.
Correct the code issue and the engine with smooth out...doubt the oil had anything to do with change in engine.[


confused,naaaahhhhh.i KNOW THE OIL HAS NOTHING TO DO WITH THE CODES.just saying I changed the oil.
picked up the MAF this afternoon and I will put it on sometime tomorrow.

 

Installing a new MAF installation is an extremely easy DIY (e.g. 5-10 minutes and a screwdriver). If that was the cause of the codes, the CEL will automatically turn off after 3 cold starts.

However, be aware that if you're due for a state inspection, you will fail the OBDII part, because there are are a bunch of sensors that need to change to 'ready' status. They will automatically reset, after driving a couple of hundred miles.

You mentioned that when you changed the oil, the filter fell apart. Had the previous owner used the cheap paper type or the premium fleece type (e.g. only use the better, stronger fleece filter type cartridge your car came with when new)?

 

hello,it was the fleece type filter,i have never seen a filter that bad,i don't think the oil was ever changed,it was very nasty,gonna go out and change the maf in just a few minutes,i will let ya know how it went.

 

oooooooooooooooooooookkkkkkkkkkkkkkaaaaaaaaaaaaayy yyyyyyyyyyyyyyyy
replaced the MAF now im getting 0300 and 0304 codes

 

Your new P0300 code indicates a Random/Multiple Cylinder Misfire Detected .

If the car is running OK, why not see if after 3 cold restarts, the CEL turns off?

Possibily after changing some coils/wires and MAF, you're still getting error codes because the previous code conditions have not been properly cleared (e.g. still stored). I know the MB STAR Diagnostic System can clear them, some generic hand readers might, or might not.

However, as mentioned above, any of the the dozen or so system sensors, used to detect/sense faults, must change from 'not ready' to 'ready'. If all is now well, after 200+ miles of driving, the 'not ready' sensors will automatically reset to 'ready'.

If not, unfortunately, misfires can be due to many conditions, having to do with proper air/fuel ratio, adaptions.......for example:

* intake leaks
* clogged fuel filter
* spark plugs (e.g. saw that you changed a couple of coils and wires, but didn't see that you changed the plugs)
* faulty oxygen sensor(s)
* faulty fuel injector(s)
* faulty catalytic converter(s)
* stuck/blocked EGR valve / passages
* burned exhaust valve

Hopefully, you can reach the prior owner to find out what maintenance service(s) have been previously done.

 

is it possible that the new MAF is faulty???????????????

 

yeah..the plugs were changed

 

It's possible, but not likely, if you bought the OE Bosch MAF from a reputable source.

That said, for my prior car, the BMW dealer sold me a faulty O2 sensor.

The CEL didn't turn off after 3 cold starts?

 

Hey nolan n all,
I see no harm in changing the oil regardless as you now know what the service interval is.
The paper element filter is good for about 5k miles. For those seeking the death penalty for engine and stretching it to 10k miles, a fleece element filter is required it is recommended for synthetic oil anyway.
The misfire is covered good here by strong members, other thoughts would be a compression test. A good cylinder is at least 100 psi. The other test is for fuel injector nozzle firing or leaking air. (several ways to test)
Wiring to cam and crank sensors might give symptoms as well.

All the Best, Gator

 

hello sir,i have replaced the maf sensor code p0304 and 0306 are gone,still getting random misfire code and now im getting p0305 and the random misfire code..any ideas...im putting the car up for sale today.i have checked for vacum leaks came up with nothing on that....