Posted by Peter Florance on January 12, 2001 at 07:17:07:
In Reply to: backfire revisited posted by MarcMc on January 12, 2001 at 02:13:24:
In the case of 530i's, I suggest O2 sensors as a diagnostic tool, not for control.
You can get generic O2 sensors for around 20.00 at most auto parts places. the threaded fitting is 18mm x 1.5. I found a Suzuki hub nut that fit and had it ground down. Later I found BMP Design carries them. Have it welded on to one of your down pipes and run the wire inside. Then either use a volt meter or one of those bar graph meters sold for that purpose (better, easier to read).
Then drive.
You be able to see the mixture as you drive (don't forget to watch where you're going).
As far as the cause:
1) binding air flow meter (car will usually idle ok)
2) bad pressure regulator
3 clogged injectors (usually shows up as poor idle too.
530i's seem prone to binding AFM because of the mechanical design.