Need some help diagnosing an issue - slight miss

[wmr71]

hey everybody,

I've recently had some issues with my 2016 X5 50 msport. Below are the items that have been replaced within the last 20k miles. Chassis has 126k miles

-brand new longblock per the Isley Settlement
-brand new OEM turbos
-brand new O2 sensors
-coils and plugs within 10k miles
-both HPFPs replaced within the last 2k miles
-low pressure fuel sensor within the last 2k miles
-both MAF sensors within 200 miles
-transfer case fluid refill and recalibration within 200 miles
-brand new crankcase vent pipe within 50 miles


I'm getting a catalytic converter error code with ISTA+. Error code 180001 is what its showing. In low gear when pushing somewhat heavy on the throttle I get a slight miss around 35mph but there is not a miss at any other range. From about 45-90 its smooth as butter.

I do have a dinan cold air intake and the filters are cleaned regularly and have been cleaned within the last 5000 miles. could they need to be replaced as they've hit their useful life at 20k or so miles?

At this point, I'm wondering if an O2 sensor is bad or if the plugs are possibly fouled as I had a drivetrain malfunction back when the HPFPs started to go. is there a chance the issue with the HPFPs may have fouled the plugs?

I've also thought maybe its an injector but there is no smell of fuel and there are no error codes pointing to this.

Lastly, I'm having a hard time believing the catalytic converter is bad but I'm grabbing for straws at this point.

With the wealth of knowledge on this forum, surely someone has experienced something similar


any guidance is greatly appreciated - thanks in advance

Mike

[m4forum]

the best solution is to measure those variants you are talking about. typically fuel starvation issues are very fast events ... doesnt seem to be the case ... but again need to measure it. Get BT OBD and Bimmerlink app so you can measure fuel pressure.
if the lambda sensors are not reading correctly certainly can indicate bad catalytic converter.
other alternative is to use ISTA to measure those parameters.