When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Recently purchased an 07 E350 with 79k miles on the clock as a little project car. The car had some known issues with the body (mostly fixed now) and a slightly rough idle (trouble shooting.) I am experienced in the mechanics of vehicles as I have built several Evo/ STi' motors and have headed several mild/major upgrades to cars such as the Evo/STi however this is my first attempt at toying with a Benz so I just want to make sure im on the right track to solving the issue. I have noticed some differences in the way Germans build cars vs the Japs! German cars are much nicer haha but they are different animals than the little 4CYL awd turbo cars im used to. I wanted to learn about something different and much higher quality than those turbo cars, and trust me im learning quickly!
I have 5 codes P0305,P0301,P0300,P0348,P0393
some picture included below
I will describe the issue to the best of my ability. When the car is idling I can feel a slight misfire on occasion. I can also hear it in the exhaust note and it seems to be consistently coming from the passenger exhaust side. I took the car for a short drive to see if the problem got worse under load which to my surprise seemed to stop altogether. I am hesitant to drive at anymore until I get a grasp on what the problem is.
The steps I have taken so far are check the Cmp sensors. My thoughts are that a faulty sensor could cause a misfire. I have verified that I have 12vDC to all 4 sensors, .01Vdc to ground. The tricky part is I am quite sure I have verified that the sensors all work by measuring the volts given when a wrench is placed close to the magnet (0 when close to wrench 5 when away.) There was one that seemed to act flaky but it could have been my hands. I also noticed that the clips were broken off of the driver side cam sensor plugs (could cause the sensor reading to flake out)
I have verified timing by setting the crank pulley at 305 degrees and each of the 4 cam markings are inside the circle (I can clearly see the circle around the text in each viewport where cam sensor goes) Based on some research this also verifies my balance shaft is good I THINK.
I have pulled the spark plugs out and noticed that all of them are a touch more oily then id like to see and are dark and aged which can cause my issues. I will be changing the plugs regardless if this is causing my issue or not
my next steps are to verify the coil packs and do a compression test on each cylinder to verfiy motor health. Another place I want to look is the Crank position sensor. I would have thought if it were faulty the car would have a much harder time idling if at all and I would have a different set of codes. I have also verfied the air intakes were properly installed against the MAF sensor. The maf sensor could be dirty or faulty as well causing the misfire issue which could MAYBE cause the cam sensor to flake out? If any Gurus are around Id like to hear of any ideas I may have missed. Im not afraid of taking stuff apart I just want to proceed with caution.
I think im right on my cylinder numbers someone check me though. Spark plugs are from left to right as follows passenger close to radiator "1"
middle "2" and close to windshield "3"
left to right again close to radiator "4" middle "5" and close to windshield "6"
Last edited by Scottyboy225; 07-25-2016 at 08:55 PM.
Reason: uploaded better timing pictures...was impaired when taking the first ones! ha
If anyone stumbles on my thread ill provide updates for more insight to the original opening post. Today i plan on revising my process for checking the cam position sensors. I think the way i did it at first may have scewed my results. I also did some research on the engine serial to verify my assumption that my balance shaft and timing components are good. engine serial is 272964-30-629049 and according to the literature ive studied I should be fine. http://www.mercedesmedic.com/check-m...-vin-m272273/#
rechecked my cmpS there good. Also went back to pull my CEL's the p0348 and p0393 are stored codes while I still have pending misfire codes P0301 P0305 and P0300. next stop is compression test and new sparkplugs then I get to play musical ignition coilpacks yay!
timing looks off to me.... forget the "p" codes. do you have 1200 or 1208 codes? IF not which i can't see why you wouldn't then maybe chain is stretched.
update for those of you that may stumble upon this. I did a compression test (cold) came back 140 psi +/- 5~ psi across all cylinders. installed new oem (non resistance) spark plugs. I cleared all codes fired it up and im pleased to say no more intermittant misfires. After about 30 minutes of blissful MB motor sound (idle time) #6 started to misfire so I pulled the coil which changed the pitch of the motor NONE. I then shut the motor down and swapped 4 with 6 while observing very little spark if any and the misfire moved to 4 so I ordered a new coil with a spare just in case. The plugs I pulled out of the car as per pictures had some wear significant on them. they are the exact plugs I installed new and i measured resistance of the old plugs and got an average of 1600OHM's....so im thinking the fouling led to a buildup of resistance which COULD be attributing to premature wear of the coils...number 6 was completely dead. hardly any spark at all. Also the more resistance a plug builds the weaker the spark will be so im quite sure my intermittent misfires are solved!! yay!
oh shes fighting me! I purchased 2 new ignition coils one to replace number 6 and another just in case....so i lost number 4 after an hour of idle and number 2 shortly after number 4. Guess I thought I would get lucky and only have to replace the one that went out. I should have known to order all 6 due to how bad the spark plugs were. more coils on the way. checked my grounds there all good
07-23-2016, 08:00 PM
