Doing routine maintenance on your customer’s car and then having a new problem on the test drive can sure ruin your day. SureTrack community member Taddia78 had a BMW X5 in their shop that had multiple misfires after doing maintenance. They posed the question to the community, and with the help of fellow community member 1Quick6 and others, they were able to resolve the issue.
The following Real Fix summarizes the interaction between them in the community that led to the solution.
Vehicle
2014 BMW X5 3.0L
Title
Multiple misfires, replaced new spark plugs.
Complaint
Customer brought car in for regular maintenance and it was running fine. After completion we now have misfire on multiple cylinders.
Diagnostic Steps Performed/Parts Replaced
We replaced the Valve cover gasket, spark plugs, and oil filter housing seal. The technician pinched the valve cover gasket and left the O2 sensors disconnected, causing a slight driveability issue on the test drive. As I was going through it the misfire continued to get worse. I located and replaced the damaged valve cover gasket and properly routed/connected the O2 sensors. I believe I caught everything, but I still have misfires. Vacuum in crank case, hiss when oil cap is removed. Smoke tested Intake and PCV system, no leaks found. Swapped ignition coils and spark plugs. Confirmed proper spark plugs and proper gap. Current DTCs include; 140010: random misfire, 140001: misfire and injector shut down, 140301 #3 injector shut down, 140310: #3 misfire, 140501: #5 injector shut down and 140510: #5 misfire.
Is there any to check crankcase vacuum to make sure I no longer have valve cover gasket issues? I am pretty sure it’s ok. I feel like I’m missing something. I have not removed the oil filter housing, found no leaks and looked ok when I removed intake. Is there anything around there that would cause this issue?
Best Answer from Community Member 1Quick6
Did you recheck the spark plugs? Tech #1 maybe messed something up there too.
Cause
It was the spark plugs! Although the part numbers matched and they were the same in almost every way, the “OEM” Bosch spark plugs from supplier didn’t meet specs. They were manufactured in Brazil, not Germany.
Correction
Swapped spark plugs out for a set of NKGs we got from the BMW dealership and the issue went away.