It has been a long time since I posted an update. Engine is running well and to sort out the air/fuel needs I installed an ECU chip that can accept custom fuel and ignition maps. This led to a dyno session where the tuner maximized the WOT (wide open throttle) maps and high demand part throttle areas.
The car runs great at WOT and with high PT loads. All areas that Dan, the tuner, focused on, but off idle and light loads were not adjusted from the base tune.
For our (California) smog test the car passed visual
, but with Dan's map I failed the 25 mph smog with high HC and very high NOX (three times the max).
The dyno tests are performed at 15mph (second gear) and 25mph (3rd gear). Both the gear and mph are state mandated. You can no longer select a lower gear for the tests. My smog guy says the Porsche guys ruined it for everyone, by fudging on gear selection. Now for the M5, neither test exceeds 2,000rpm.
Here are the maps that Dan provided after a day of dyno tuning (last year).
Here are the part throttle fuel and ignition maps that I ended up creating last weekend to pass smog. It didn't take too long using an LM-2 and recording AFR values in 1,500 - 2,500 rpm ranges. It is hard to see, but we backed off the ignition a lot at the low load/low RPM ranges and reduce fueling as well.
This just barely got me by as my HC and NOX values are just below the threshold. It took three tries, making progress each time. The car runs much smoother off idle now. Driving in stop and go traffic/parking lots is also much easier as the ECU is no longer hunting (by swinging the fuel injectors (rich to lean) to find 14.7 in the low rpm ranges. I hadn't realized how much I compensated for this by pushing in the clutch early before stops and getting out of gear while just rolling along. It feels much more like Donna's 528e at parking lot/driveway speeds...which is a good thing.
Learning how to adjust the fuel maps was fun, but passing smog was even better.
Dean