Mercedes-Benz Forum banner

1 - 6 of 6 Posts

·
Registered
2007 Mercedes S550 2008 Mercedes x164, 2007 Mercedes w164, 2001 Mercedes W210 E55 AMG
Joined
·
367 Posts
Discussion Starter #1
I will try to start from the beginning so that anyone reading this can follow. I bought my 2007 Mercedes S550 with 146,923 miles and it was in much needed repair both mechanically and also needed bodywork. I am one to like project cars cause they give me a hobby to do. The first repairs I had done from my mechanic was what I believed to be priority which was the suspension parts. I had the upper/lower control arms,sway bar links,inner/out tie rods, all the way around I had new brake pads and rotors installed, as well as motor & transmission mounts replaced , transmissions service, oil change , and finally a wheel alignment. With all that out of away I started on my own to sort through the many obd II codes I had gotten along with trying to figure out why the check engine light was on . When I first scanned the car there was so many codes that said " stored" that I want to make sure that these codes were still active so I took the advice of a fellow forum member and deleted them. After driving 100 or so miles I figured that i would re-scan the car and see which codes came back. Well unfortnately a lot of the codes came back and a lot of them had to do with faulty coils, misfiring, and air mass flow sensor . After doing my research on the codes I found I decided to order and install brand new delphi coils and oem spark plugs as well as an oem air mass flow sensor. After doing so I got rid of the check engine light and the car seemed to be driving fine and there were no issues at all. Then after a month of so I noticed that when the car was idling it sounded like it was misfiring or skipping ( really the only way I can describe it) . I decided to bring it to my mechanic and have him take a look and also scan it. When he hooked up his OBDII scanner and not a star as he does not have one it gave a misfiring code of P0303 . He decided to pull the coil and spark plug from that cylinder and swapped just the coil with cylinder 2. He told me he was going to clear the code and that I should drive the car for 50-100 miles and come back to have the car scanned again. I took the car for a decent drive over the next couple of days after going to the mechanic and still noticed the misfiring or skip when the car was idling so I decided to scan the car with my OBDII and I "store " codes of P0300 and P0305. The P0300 code from my research is a general misfiring code and P0305 is a misfiring of cylinder 5. Though the P0305 misfiring of cylinder 5: Worsening of exhaust emission values.I tried looking up P0305 code and talks about spark plugs, coils , fuel pump ( pressure ) which are all brand new and It's very odd that when my mechanic scanned in 3-4 days I only code the one code and that no other code pending. My mechanic is suggesting that it might be a faulty catalytic converter and I am thinking its either a fuel injector or O2 sensors. Please any information or help would be great
 

·
W221 & Audio Moderator
2013 S550
Joined
·
10,874 Posts
You really need to have the car scanned with a Mercedes DAS, not OBDII. Lots of info on this forum and on the W220 forum as to why. OBDII just isn't going to give you what you need.
 

·
Registered
2007 Mercedes S550 2008 Mercedes x164, 2007 Mercedes w164, 2001 Mercedes W210 E55 AMG
Joined
·
367 Posts
Discussion Starter #3
skylaw,

I have gotten what I think is the right diagnosis. It seems that all my oxygen sensors are shot. The car has 152k mile so I figured it would happen soon. I need the part #s to the pre cat ones as well as the after cats. Also I am trying to figure out the tools I need to remove and replace the O2 sensors. Thank you.. The voltage of each O2 sensor is .11, 64, 1.00 , .12. from my understanding while the car is running and engine warmed up the O2 sensors should be 1.64 or better.
 

·
W221 & Audio Moderator
2013 S550
Joined
·
10,874 Posts
Thanks for getting back to us - unfortunately, I don't have the answers you request. Wish I could help more.
 

·
Registered
2007 Mercedes S550 2008 Mercedes x164, 2007 Mercedes w164, 2001 Mercedes W210 E55 AMG
Joined
·
367 Posts
Discussion Starter #5
Just an update to my situation. So I decided to remove the coil and spark plug that was in cylinder #3. I replaced just the spark plug in cylinder #3 and to my surprise no more misfire! All the plugs were brand new but I must have gotten a faulty one from the dealership maybe I did something to it when I was installing it. The mechanic checked that it was gaped correctly and did visual inspection of it. Needless its finally fixed. I am hope this helps others
 
1 - 6 of 6 Posts
Top