2001 BMW X5 3.0i running lean!
Hello everyone new to the forum... Few weeks ago bought a 2001 BMW X5 3.0i w/ 108K miles on it. Love the car, but it started throwing P0171 & P0174 codes and they are giving me quite a headache. First thing that came to mind was dirty/bad MAF so I cleaned it out and reset the codes. Went with 2 days without SEL and came back on. I didn't really had any symptoms before or didn't notice any... Now I do feel a small rough idle.
I've visually checked for cracks and also sprayed brake cleaner and can't find any leaks on major intake hoses. I also took out the dreaded DISA valve and looks just fine to me. I have a scanner and was looking at my O2 voltages and all 4 sensors are at .03-.04 is this normal below the 0.1volts?? I knw it means system is lean but all O2 sensors including downstream? Thinking it might be the Front O2's .
Another weird thing I noticed, I unplugged the MAF while car is running and engine didn't turn off and I looked at my front O2 voltages and they went up to .4 - .8 instantaneously , if I plug the MAF back in engine shuts off. So I thought it was a bad MAF and went to dealer where I bought the car and they switched it with another X5 they had in the lot and I took readings and the issue is still there.
Would appreciate some guidance. Thanks.