[TerrelKeim]

Car is fine and drives fine until warm. The car (BMW 2011 335i xDrive n55) proceeds to go into limp mode and sometimes low oil pressure display. CANNOT figure this out. This only happens when idling and I can clear the codes and I can drive it normal until the next red light…. Does it need a walnut blast in my valvetronic motor bad????
I have the codes clipped.

[Yotaismygame]

I mean....seems like the answer is there in the codes. Vanos solenoids......Pull them out and clean them or replace. Pretty easy

[whyzee125]

With 2 VANOS codes, it seems obvious you need to start there. Bet that takes care of it.

I've heard of N55's getting low oil pressure warning when warm due to worn rod bearings too, so that could be another possibility but vanos is both more likely and cheaper. Start there.

[TerrelKeim]

Originally Posted by Yotaismygame

I mean....seems like the answer is there in the codes. Vanos solenoids......Pull them out and clean them or replace. Pretty easy

I actually put new vanos solenoids in and the only thing that changed was an increase of fuel mileage.

[whyzee125]

Originally Posted by TerrelKeim

I actually put new vanos solenoids in and the only thing that changed was an increase of fuel mileage.

That's odd. Something is definitely amiss with your VANOS. I think N55 had an issue with the bolt heads breaking off one of the vanos units and dropping in the oil pan. Did yours have this repair done already? I think all US N55's were either recalled or got a TSB on it. Might be worth looking into as these codes aren't there for no reason.

Did you use OEM solenoids? Aftermarket ones are hit or miss but that wouldn't explain the oil pressure issue.

[wheela]

Originally Posted by whyzee125

That's odd. Something is definitely amiss with your VANOS. I think N55 had an issue with the bolt heads breaking off one of the vanos units and dropping in the oil pan. Did yours have this repair done already? I think all US N55's were either recalled or got a TSB on it. Might be worth looking into as these codes aren't there for no reason.

Did you use OEM solenoids? Aftermarket ones are hit or miss but that wouldn't explain the oil pressure issue.

If there's actually something wrong with his oil pump and pressure is too low, I wonder how low it would have to be before the vanos system malfunctions and throws codes (and causes limp mode)? The oil pump is driven mechanically by the engine right? Perhaps that's why his issue pops up when he comes to a stop, if the engine rpm dropping dips the oil pressure enough to mess with vanos operation? Totally theorizing here, I'm not familiar with details of how the oil pump and vanos system works, so please disregard if I'm way off base.

[wheela]

As the car warms up, the oil viscosity will drop, so if something is wrong with the pump, that drop in viscosity might be enough drop the oil pressure just past the threshold of messing with vanos operation.

It would be intersting to see a log (including oil pressure) of this issue happening.

[wheela]

These cars can control oil pressure based on a map, so I'm guessing there is some kind of valve or regulator in the system that the DME can adjust to control oil pressure? If so, then if oil pressure is off, it may not necessarily be the pump - it could also be whatever the car uses to regulate or monitor oil pressure.