Electrical issue showing up as a misfire?
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From: Central Texas
2004 E55 AMG
Electrical issue showing up as a misfire?
Stick with me here this will be a lot, I am confused as hell and want to see if this even makes sense to anyone else.
2004 e55
stock (aftermarket headunit)
140k miles
I have a random misfire that keeps showing up on cylinder 6. The car decides when it wants it to show up, it either runs perfectly, or that cylinder is dead.
I’ve swapped plugs, coils (wires), injectors, checked voltages, ohm’d, you name it several times.
For a bit of background.
This all started after the car sat for a while, like 3 months. I got it back on the road and drove it 20 or so miles, on the way back home that night my wife was driving and I noticed the check engine light came on once we hit our exit, and it had a noticeable misfire. Cue me being pissed about it, the car sat for a long time after that before I did anything else. When I went to start working on it again, the battery was so dead I couldn’t get the car to jump. I pulled the battery and had to trick the charger to get it charging. After a few days with it on the charger, my tester said it was dead. The battery was only a year old and I took it back and swapped out a new one.
I put a charge on the aux battery, verified that one was good and unplugged the bcm to reset it. The car ran perfect for probably a month.
A few weeks ago, my wife and I went shopping and I started and stopped the car probably 15 times on short trips. The last stop, the starter physically stalled and it took a second hit of the button to fire off. Once we got to our exit, like clock work, the misfire came back. It’s always cylinder 6.
I hooked up the computer to check and I noticed initially the voltage was 11.9v. I knew it was way too low but let the computer do its thing, but by the time I was done with the computer the voltage had worked its way up to 12.4v with the engine off.
To verify, I started the car and I have anywhere from 13.8v to 13.94 volts while running.
I did notice I had a code for the bcm, but I can’t for the life of me remember if I cleared the codes last time I unplugged it.
Does this make sense a voltage issue could show up in this way? Am I missing something painfully obvious?
Thanks for reading my life story.
2004 e55
stock (aftermarket headunit)
140k miles
I have a random misfire that keeps showing up on cylinder 6. The car decides when it wants it to show up, it either runs perfectly, or that cylinder is dead.
I’ve swapped plugs, coils (wires), injectors, checked voltages, ohm’d, you name it several times.
For a bit of background.
This all started after the car sat for a while, like 3 months. I got it back on the road and drove it 20 or so miles, on the way back home that night my wife was driving and I noticed the check engine light came on once we hit our exit, and it had a noticeable misfire. Cue me being pissed about it, the car sat for a long time after that before I did anything else. When I went to start working on it again, the battery was so dead I couldn’t get the car to jump. I pulled the battery and had to trick the charger to get it charging. After a few days with it on the charger, my tester said it was dead. The battery was only a year old and I took it back and swapped out a new one.
I put a charge on the aux battery, verified that one was good and unplugged the bcm to reset it. The car ran perfect for probably a month.
A few weeks ago, my wife and I went shopping and I started and stopped the car probably 15 times on short trips. The last stop, the starter physically stalled and it took a second hit of the button to fire off. Once we got to our exit, like clock work, the misfire came back. It’s always cylinder 6.
I hooked up the computer to check and I noticed initially the voltage was 11.9v. I knew it was way too low but let the computer do its thing, but by the time I was done with the computer the voltage had worked its way up to 12.4v with the engine off.
To verify, I started the car and I have anywhere from 13.8v to 13.94 volts while running.
I did notice I had a code for the bcm, but I can’t for the life of me remember if I cleared the codes last time I unplugged it.
Does this make sense a voltage issue could show up in this way? Am I missing something painfully obvious?
Thanks for reading my life story.
