I have been troubleshooting several misfires on my 2010 BWM 535i Xdrive. I had a misfire on 5, 2 and random. To troubleshoot this I have replaced the following:

• All Plugs
• All Boots
• All Injectors

I had a hard time finding a tool that would help me code my injectors so I just ran my car on my old injectors codes. It ran a bit rough, which was expected however I had no misfires. I even drove it around town to run some errands with no problems. It sat for about a week and I started it again and it ran just fine, idle was about 1000 RPM's. Then 30 seconds later the RPM's went up to about 1300 and then the check engine light turned on. I got a cylinder 3 misfire. I erased the code and waited until I got my IMPA software set up and my K-DCAN cable set up to code my injectors. I thought since my injectors were not coded it caused a misfire. Now that I have coded my injectors I am constantly getting a cylinder 3 misfire. I just don't understand why I am now getting a cylinder 3 misfire when after I replaced everything initially things worked great.

I just need help in troubleshooting this error

Thanks,

DocDages

 

Did you check all connections closely?

I ask because I had a cylinder 5 misfire and upon checking the clamp at the injector, it was 0.5mm unseated. I didn't think that was a big deal, but I decided to re-seat the connection to make it flush. That actually fixed it.

On another occasion, I had a cylinder 3 misfire. That time, all I did was remove the plug and re-install it and all was well.

 

FYI, I recently replaced all injectors with index 12. One injector I pulled was missing it's decoupling ring. Wanna guess which cylinder had the misfire the most? Yep, that one. Wanna guess the previous mechanic? Yep, me. Works great now.

Otherwise I'd start by swapping the coil with another and see if the misfire moves. New coils can be faulty. It the misfire doesn't move, swap the plug. Then you can pull the injector and examine it closely.

 

Get a "noid" light off amzaon for about $11 and test the pigtail/connector at injector #3. if it pulsates/flashes whenever you crank it up then you know you have a good connector/pigtail.

I second replacing the coil pack (or swapping with another cylinder) to see if that continues to misfire.