[RocketSurgeon]

Hey, I'm having issues with a 2009 BMW X5 N52. Sometimes the car runs fine, but it will occasionally go into limp mode with the half-engine light, DSC light, and 4x4 light. The car will have zero acceleration until restarted. Sometimes the issue occurs immediately upon startup. It has a code 2D58 DME, Internal Fault: monitoring, nominal torque. I cloned the DME to rule out hardware issues, and performed a software update. The intermittent issue persists. I found large vacuum leaks at the valve cover which have now been fixed. It will pass a smoke test. It also has a tiny crack at the bottom of the rear catalytic converter, though fuel trims are fine. I believe the problems appeared around the time the alternator was replaced. I just did battery+registration. Any ideas on what may be causing this? Thanks in advance.

[bmchicago]

check for clogged cat

[RocketSurgeon]

check for clogged cat

That's a good idea, I just checked and both cats have less than 1psi of back pressure.

[bmchicago]

you put camera in there to check for damage?

[RocketSurgeon]

you put camera in there to check for damage?

Yes, the ceramic honeycomb looks perfect.

[SkeYT]

Past all details from ista about error (double click on it) and freeze frames if you have it..

[RocketSurgeon]

Past all details from ista about error (double click on it) and freeze frames if you have it..

Here are the codes and details. The DSC and VTG test plans say that the issue lies elsewhere and to check the DME first. The DME test plan says it's an intermittent code that can be ignored. Could there be some kind of odd drop in communication through the junction box? 

       

[willisodhiambo]

DSC DME interface. There is loss of data between the two. Within the DSC is there any parameter for torque?

Also check the eccentric shaft sensor. I think torque is also related to throttle position. Interesting problem

[JBScuba]

I second the eccentric shaft sensor, I have had several fail without setting a fault, it will definitely cause a lack of power. You should check the connector for oil, they often leak internally. If clean you can always unplug it and drive it to see if your issue returns. The engine will just default to max lift when unplugged.

[RocketSurgeon]

That's a great idea with the eccentric shaft sensor, I didn't realize they could fail without codes. The valvetronic does sound a little unusual. Unfortunately the customer doesn't want to go any farther with this car, saying she wants to trade it in.