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I got some misfire codes on my 2008 535xi the other day. It was cylinder 3 & 6 according to my code reader.
I changed out all the plugs with new Bosch ones. After doing that the code for cylinder 6 went away but cylinder 3 stayed.
I then went and bought a new coil pack and replaced the # 3 pack. Code still stayed. So then I swapped the packs around seeing if I could get the code to move cylinders. No matter what I did it stayed on Cylinder 3.
Next, I pulled the fuel injectors for cylinder 3 &4 and swapped them. Code is still saying cylinder 3.
I'm not sure what to do next or if I missed something along the way. I should mention between all my steps I did clear the codes and it kept coming back at Cylinder 3. Someone told me that the next step would be the wire harness from what I can find online though thats a $500+ item. So trying to avoid that if I can.
Any ideas or help anyone has would be appreciated!
I wouldn't say it's the harness did you look at the cable to 3 and see if there is anything that looks bad. Clear the code then disconnect the battery for 15 mins. What plugs did you use? Drive the car around to see if it the misfire moves and doesn't come back. A leaking injector cuts fuel to the cylinder
Last edited by seanjordan20; 12-14-2019 at 05:22 PM.
Let's start some brain storming. Here's a few misfire ideas to get you thinking.
o Look at #3 spark plug for oil in the bottom well or oil somewhere in the #3 ecosystem that could be causing a misfire
o Look at the plug again. Is it wet with fuel? How about swapping injector #2 with injector #3 this time
o O2 sensors can cause a misfire. 02 sensors covered with oil?
o Check the two braided ground cables next to the spark plugs. Are they loose and should be tightened? Are they corroded and should be replaced?
o Injectors not firing correctly. Clean with strong injector cleaner
I wouldn't say it's the harness did you look at the cable to 3 and see if there is anything that looks bad. Clear the code then disconnect the battery for 15 mins. What plugs did you use? Drive the car around to see if it the misfire moves and doesn't come back. A leaking injector cuts fuel to the cylinder
I looked at the wire and I don't see anything that is bad. However, when looking at the injector the port where the wire plugs in is broken near the top. The wire still can plugin and it feels secure when pushed all the way in. I don't think it's having any effect on the connection.
I used the Bosch replacement plugs. They look just like the ones I removed.
To disconnect the battery I do that in the trunk? Do I just take the positive off or both?
Let's start some brain storming. Here's a few misfire ideas to get you thinking.
o Look at #3 spark plug for oil in the bottom well or oil somewhere in the #3 ecosystem that could be causing a misfire
o Look at the plug again. Is it wet with fuel? How about swapping injector #2 with injector #3 this time
o O2 sensors can cause a misfire. 02 sensors covered with oil?
o Check the two braided ground cables next to the spark plugs. Are they loose and should be tightened? Are they corroded and should be replaced?
o Injectors not firing correctly. Clean with strong injector cleaner
o CCV cracked or cracked vacuum lines?
o Fuel pressure in the rail adequate?
I'll check some of these things your mentioned. Thanks.
Ok so here is the update: I removed the negative from the battery. While I did that I swapped the #3 injector with the #2 injector. (so the original #3 injector is now on the 4 cylinder, the #2 injector is on the 3 cylinder, and the #4 injector is on the 2 cylinder).
I also checked the braided cables next to the plugs. They all look good. I can't see anything that would give me a reason to think they are damaged.
It then hooked the battery back up and started.
I'm still getting a misfire on #3. while the engine is running I pull the plug on the #3 coil pack and there is no change in how the engine runs so I still believe that cylinder is just not firing.
On top of that though I'm not getting the following messages from the car (no additional codes are showing up):
AWD and DSC malfunction
Start-off assistance inactive.
Let me know if this sparks any more thoughts.
@scottalexander is there an easy way to check your last 3 suggestions?
You have a new plug in #3 cylinder and a new coil pack for #3.
If you pulled #3 coil pack off the #3 spark plug and there is no change in how the engine runs, it would appear you are not getting voltage to the coil pack.
You have a new plug in #3 cylinder and a new coil pack for #3.
If you pulled #3 coil pack off the #3 spark plug and there is no change in how the engine runs, it would appear you are not getting voltage to the coil pack.
Alright, so I have a new development. I checked all the wires and it appears to all be in good condition. I did go get some CRC electrical connector cleaner and cleaned them. After that, I drove around the block and the AWD and DSC Malfunction went away as well as the start assistance error went away. However, about halfway through the drive, the check engine light came back on and it was Cylinder 3 again...I could feel it wasn't firing the whole time though.
The new development though is once I was stoped I could see white smoke coming up from under the hood. I opened the hood and it seems like the source is coming from the back left of the engine. Right to left of cylinder 4 & 5 but come up from way down next/under the engine. I've attached a picture and video. Hopefully, you can see the smoke and perhaps hear something that can give someone an idea.
I'm thinking VC gasket. Too much smoke leaking from multiple places. Is there oil getting on the O2 sensor wire on the at side. Along the should be a metal shield is there oil on it.
Last edited by seanjordan20; 12-21-2019 at 07:43 AM.
12-14-2019, 02:19 PM
Cylinder 3 Misfire
