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The check engine light came on a couple weeks ago and I could tell the car wasn't running at 100%. I scanned the car and got the P0305, misfire cylinder 5. I changed out all the spark plugs and cleared the code. The code came back on, so I changed the coil on cylinder 5. Well I believe it is cylinder 5, the middle one on the driver side. I cleared the code again and the light still came back on for cylinder 5. Can someone point me in the right direction of what to check or do now. Thanks!
The check engine light came on a couple weeks ago and I could tell the car wasn't running at 100%. I scanned the car and got the P0305, misfire cylinder 5. I changed out all the spark plugs and cleared the code. The code came back on, so I changed the coil on cylinder 5. Well I believe it is cylinder 5, the middle one on the driver side. I cleared the code again and the light still came back on for cylinder 5. Can someone point me in the right direction of what to check or do now. Thanks!
I had a flashing check engine light, and there was clearly a misfire for my 2014 E350 4MATIC, have you changed your spark plugs? what year and model is yours? that may be the issue.
Swap coil pack and spark plug to any other cylinder. If the misfire moves to that cylinder, replace the spark plug or the coil pack. If the misfire stays where it was, it's the injector.
I changed all the spark plugs about a month ago. I changed the coil on cylinder 5 about 2 weeks ago. Still have the same code. How do I check the injectors and why would a faulty injector throw a misfire code?
Swap coil pack and plug just to be sure. Can't count how many times I've had bad parts out of the box. If the misfire stays on 5, replace the injector.
How could a faulty injector NOT cause a misfire? How would a cylinder fire if it's either not getting any gas or if it's getting flooded with gas?
As far as how do you check an injector, this is how.
Last edited by Darel; Mar 9, 2020 at 09:42 AM.
Reason: add
I had similar issues with my 2012 e550. Started with swapping coils, plugs, cam shaft sensors but was not able to resolve the issue. Same symptoms as you described. Then hocked up a scanner and while driving finally got a code for oxygen sensor (screen shot not below but will see if I can find that).
It was the driver side upper oxygen sensor and once it was replaced, no issues and it has been close to a year now and car runs great. Hope this helps with the debugging. Below images are what codes I was getting.
I am not the best at reading this data unfortunately. I just pulled the data from mine and reading seems to match what you have captured. I was lucky that eventually a code popped up on mine as car would run fine and then all the sudden check engine would flash and loose power.
If you clear the code, does the same code come back and does it come back right away?
Yes, the same codes keep coming back.
They are:
P0300
P0301 Cylinder 1 Misfire
P0305 Cylinder 5.3 vortec
I have changed all the plugs and I orginally put a new coil on cylinder 5 and then swapped the coils around and still have the same codes come back.
Now many motorists often start to fly the reels, I am not even surprised. I myself was changing about 2 months ago, looking for a better coil to pick up, of course, you need to know the details. That is why I decided to read about it first, and then I will make a decision on these coils. In order not to have to change them again immediately, because much depends on compatibility. I decided to take such a Yikesai Ignition Coil Pack - 2013, as it really fit perfectly, I just read the information about the best coils for 5.3 vortec https://carfluidsexpert.com/top-6-be...or-5-3-vortec/ , and here were just painted the details of this case, just judging by the description, and in general for old cars, it is probably the best option, but already look and study for yourself to make a kind of opinion. Good luck.
Cyl 5 misfires can indicate a bad valve seat. Might wanna have some real diagnosis done, if the seat drops, you're looking at serious damage/cost to fix...
Cyl 5 misfires can indicate a bad valve seat. Might wanna have some real diagnosis done, if the seat drops, you're looking at serious damage/cost to fix...
This is an interesting thread. In talking to one of my indy's around last Christmas we were discussing Mercedes quality trend and he mentioned an 2014? S Class that had dropped a valve seat. Sounds like this is the issue that he was referring to.
The 02 values while the car is running should be sweeping from .1 to .8 after the car warms up ( that's 100mv to 800/850mv) if one is locked at lets say 490 then that sensor is fouling. The cat temps seem to be within range. Some of the other data my brain won't process at the moment. Fuel pressure seems low if DI unless it's reporting the feed pump pressure. I'll go run live data on mine to compare as my car doesn't want any of my money at the moment.
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