P1083 and P1085, P0171
 

I bought this 2001 x5 3.0 with the above code showing after several days (or longer) I was basically assuming that this is just a vacuum leak somewhere. Previous owner got tired of dealing with it.

I cleaned the MAF, checked the intake hoses and they're in good shape. I can't actually do a thorough check on CCV since I can't see it well, just tried spraying with carb cleaner around the area for any changes and yield nothing.

I run OBDWiz to check for fuel trims and 02 sensor voltages. The 02 sensor voltages show nothing unusual but the STFT on both banks. STFT1 goes up to 18-20 and slowly dies down when it's warmer to 10 or sometimes 5. STFT2 is within +-5% and sometimes act the same way as STFT1 (at 18-20%) When I rev the RPM to 2500, the STFT on both banks go to 0% but the weird thing is that the LTFT1 and 2 are 0 (always 0) Am not sure if this is an issue with the scanner.

Is it safe to assume that I have a valve cover leak that is small and seals up when warm? Is it normal to have LTFT trims of 0% even when you have a lean code?


when I ran BMW scanner here's the code;
CB [203] Oxygen Sensor Control Bank 2 Control Limit Mixture Limit Rich
CA [202] Oxygen Sensor Control Bank 1 Control Limit Mixture Limit Rich
E3 [227] Oxygen Sensor Controller bank 1, deviation too great deviation rich

I run some more test and this time I rigged up a smoke machine. Well the bad part about this smoke machine (the one they used in parties/halloween) is that it doesn't have pressure to go inside the engine, I could see smoke out of the filler cap but not much to detect any leaks. I also happen to break the crankcase tube going into the ccv when I tried to loosen it (so brittle at this age) fixed that with elastic tape and resorted to using the brake cleaner spray method again. This time it always point to the DISA valve, everytime I sprayed on it the STFT on both banks go max and takes a while to recover. The o-ring is bad on this and sometimes when it warms it just seals things up and everything is ok (actually it's not consistent and there are times that it never settled down) When the STFT goes beyond or extremely high it's normal for the LTFT to be 0 in this case... it might take a while for the LTFT to show up... ordered the o-ring on e-bay and am thinking of what to do with the broken CCV hose.. should I do the CCV delete mod or replace it?

Rebuild the DISA valve with the well known kits. Replace the whole CCV set-up as well. Both are known issues.

You don't mentioned mileage, whether you checked intake air filter, replaced spark plugs, fuel filter (good idea but not likely to change the codes) or O2 sensors.

update! no more lean codes
 

I took out the DISA valve today and I was able to pull it out without any effort, the gasket is flat and the bad news is that the flap is not working. I tested the vacuum and is working fine, it's just that the flap is disconnected. I used the ford thermostat housing o-ring and it was thick, I have to shave off some if and use lithium grease when installing it back. No lean codes pending and my STFT is hanging at 6% on bank 1 and 4% on bank 2. I'll find another DISA valve to replace it tomorrow or buy the fix kit. Hopefully the vibration at idle is caused mainly by the DISA valve and not the engine mounts (I'm still suspecting engine mounts) One trick the owner did to hide the vibration is to deflate the tires and blame the weather for the low pressure.

There's a difference on the way it drives now compared to when it was leaking..