Need some advice on P1158 code please.

[B5M4W0]

Hello everyone,
Heres the scoop, '01 X 4.4 103k miles. I bouhgt the X 3 months ago, MIL light was on intermintently, got a scanner said cam sensor was bad. Changed the sensor and all was good. Cleared the code allowed reasonable time for fuel trim etc. to reset/learn. The light stayed off but it never seemmed to run to its potential. It pulls good up to about 4k rpm then kinda of hesitates like its running out of fuel. It just doesnt feel smooth like the 540.
I took it on a road trip two weeks ago and half way there the MIL came back along w the ABS and traction lights. Code said system too lean bank1 and Vehicle Speed sensor A malfunction. I changed the fuel and air filters, cleaned the MAF w CRC MAF cleaner and fogged the intake w cleaner while running. Cleared the codes and went for a ride. It ran 10x better! Hesitation was gone and acceleration was stronger than ever....Then the light came back on. Its still runs just as well but its still not as good as it could be in my opinion. Now it says P1158 trim adapter bank one. My next step is to check for vacuum leaks, retorque the intake and check all connection on intake and vac hoses. Where do I go next? Are there values to test the MAF?




The P0500 is a generic code for vehicle speed sensor A.. Is it a wheel sensor or another sensor on the tranny? Does the A signify location or anything to BMW? Any input on either of these problems would be appreciated. Thanks for your time!

[Wayne's World]

Do some reading here as I can see the path you're headed down, it will give you some understanding of fuel trim parameters: FUEL TRIM(MING) DIAGNOSTIC TIME | Motor | Find Articles at BNET

I'm currently troubleshooting an issue of my own similar to yours. No real success yet though.

[B5M4W0]

Thats definately a helpful article. Thank you. My scan tool has freeze frame that shows fuel trim % at the point it was out of parameter... but whats allowable?? .It also shows vehicle speed to be zero all the time. Are they connected, if the pcm uses load % would it use speed also?? The light came on at idle. I'm guessing Mass Air problem. I wouldnt think O2's on both banks went bad literaly over night or at the sametime. Checked for vacuum leaks, cracked boots and hoses. Thanks again

[Wayne's World]

If I'm not mistaken - at idle is when vacuum is greatest.

Also load is calcuated by using the MAF and RPM when the car is moving or in drive. At idle, it enters a closed loop and usese predetermined value for the MAF, injector pulse width and the RPM of idle.

When using a predetermined value, if you have a vacuum leak, the O2 sensors play no part in modifying the injector pulse width so it can't compensate or add fuel for any extra unmetered air. The O2s simply report a lean condition.

[B5M4W0]

Well after removing the actual maf sensor from the housing and cleaning about 4 times w CRC the codes for too lean and fuel trim are gone and the light is out.Nice 6$ fix. Still havent figured out the ABS/traction problem.

[lo_jack]

Originally Posted by B5M4W0

Well after removing the actual maf sensor from the housing and cleaning about 4 times w CRC the codes for too lean and fuel trim are gone and the light is out.Nice 6$ fix. Still havent figured out the ABS/traction problem.

Vacuum is greatest at idle, or when you are running high RPM in gear and take your foot off the throttle, or downshift, or both.

The ABS traction deal is likely a speed sensor at the wheel, or possibly the steering angle sensor. Those are both throw those lights occasionally.

[B5M4W0]

Are there any values listed any where to test each sensor with a meter? or just test them all and change the one that reads different.

[B5M4W0]

Just an update to help others. The ABS light was on because the right wheel sensor was cracked and the wires were broke where it fits into the hub. It couldn't be seen w just visual inspection. I didn't get the code read or go to the stealer. I just took a gamble and bought a rear sensor on Ebay for 43$. With out jacking up or removing wheels I just plugged the new sensor into each wheel location and turned the key. When I got to the right rear the lights went out and have stayed out for over 400 miles. Apparently if you have a problem with a wheel sensor and fix it the lights will go out on there own. Refering to my original engine light problem, it is also still out after over 1k miles. Clean those MAFs!