Finally Cause of Cylinder 7 Misfire Documented
Thread Starter
Member
Joined: Dec 2015
Posts: 105
Likes: 69
From: Phoenix, AZ
2012 C63 with P30, LSD, and EES Supercharger, 1959 Plymouth with Viper V10 and Tremec 6sp
Finally Cause of Cylinder 7 Misfire Documented
Left Lambda frozen at 1.00. Right Lambda on a different screen with variable voltage.
For a few months my C63 with only 30k miles has had an intermittent dead cylinder and CEL that gives code P0307 for cylinder 7 misfire. It usually starts missing while driving down the freeway at about 75mph and never stops until I turn off the car and then restart it. Even if I only wait 30 seconds and restart the miss is gone for a while. I have pulled the plugs and none are fouled so I was thinking it had to be a lack of fuel, not spark. I read here several people saying that bad O2 sensors could cause the problem but have checked the O2 sensors with my hand held scanner several times (including just yesterday) and they always tested fine. Well today the misfire returned and I finally had the brilliant idea of scanning the car while it was missing before I shut it off and guess what? The Left pre-cat sensor was totally dead! There must be a German gremlin in there that causes the O2 sensor to intermittently quit working and then mess with the fuel supply to some cylinders more than others, and never throw a CEL for the O2 sensor!. I am an old guy and have been playing with FI cars for many years and have never seen anything like this. If I hadn't read about the O2 sensor issues on this site I would never have thought this possible. Thanks to everyone here for making this great information available for us crazy folks who like to search for answers and not randomly replace parts.
SPONSOR
Joined: Sep 2014
Posts: 3,647
Likes: 818
From: Worldwide
2007 Mercedes E63 AMG
thanks for the info!
Junior Member
Joined: Aug 2005
Posts: 55
Likes: 7
From: Little old England
AMG CLS63S SB.
Well today the misfire returned and I finally had the brilliant idea of scanning the car while it was missing before I shut it off and guess what? The Left pre-cat sensor was totally dead! .[/QUOTE]
Odd that didn't show up in the history though?
Odd that didn't show up in the history though?
Super Member
Joined: Oct 2012
Posts: 538
Likes: 89
From: Hollywood, CA
W209, W124
Holy Necromancy Batman ! This thread has been dead for 8 years !
Junior Member
Joined: Aug 2005
Posts: 55
Likes: 7
From: Little old England
AMG CLS63S SB.
