Posted by Peter Florance on December 11, 1998 at 06:40:13:
In Reply to: Intro and AFM question posted by Carlos Lopez on December 10, 1998 at 23:05:01:
: OK so here's my problem, I failed the emissions! D'OH! I replaced the AFM with a used unit, the shop guy said they drilled out the adjustment rivet but there was no adjustment to this bad boy and the rest of the story you already know. So is there a better solution than just trying yet another AFM?
: I just replaced the ignition wires, plugs, points, cap was changed not too long ago and the car still exhibits a miss or shudder while driving, any ideas on what to replace next? Sorry for the length of the message.
Things to check:
Check fuel pressure. Pressure regulators have been known to stick at high pressure (something with diaphram?). Should be 2.5 bar (~35 psi with vacumm hose disconnected)
Air flow meter screw is only for CO @ idle!. If you failed CO at cruise it may be because you don't have thermal reactors. Some one told me (maybe Scott Stewart) that 530i's run rich in order to make reactors work. You could try tightening up the air flow meter spring 5 teeth or so to lean it out. You ought to get a muffler shop to weld on threaded fitting (18 x 1.5mm I think)for O2 sensor. Then you can use voltmeter to make adjustments. ~.5 volt for 14.7 : 1 Higher voltage is richer. Get the cheapest Bosch O2 sensor you can find (mine was ~$29.00).
Peter