Intermittent rough idle

2002 BMW 745
150,000 MILES • 4.4L • V8 • 2WD • AUTOMATIC
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RALLENBY
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Hello, my car listed above 745i has a rough idle intermittently.. I just rebuilt heads and replaced timing chain guides myself. New AGM fully charged battery. Smoked tested and diagnosed at BMW dealership. Misfire on bank 2 5, 6, 7, and 8.
I used AGM timing tools when I set the cams.

Is it possible that the timing is out on the left side just slightly enough to get misfires, but close enough the eccentric somewhat compensates for it?
Jun 28, 2019 at 7:14 AM
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STRAILER
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Camshaft timing is important but it should give a code if there is a problem. there is a ground wire for the coils on each side of the engine can you confirm there is a good connection? Please let me know.
Jun 29, 2019 at 7:33 PM
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RALLENBY
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Yes, confirmed all grounds are clean and secured properly. I did a full continuity check on all pins. Voltage check on all connectors 14 volts engine running. Ground continuity on all ground pins.
Jun 30, 2019 at 12:03 PM
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STRAILER
  • ✓ASE Certified Mechanic
  • 54,832 POSTS
  • ASE Certified Mechanic
It sounds like it is lean due to a MAF sensor that needs to be replaced which is common. The hot wire becomes contaminated you can try cleaning it but I have better results with a new sensor. here is a guide to walk you through the steps and diagrams below to show you how on your car:

https://www.2carpros.com/articles/how-to-replace-a-mass-air-flow-sensor-maf

Check out the diagrams (below). Please let us know what happens.
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Jul 1, 2019 at 10:54 AM
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