So, if anyone recalls, I recently did a pretty comprehensive overhaul on the '99 Bonne as documented in this thread: Running lean after overhaul - Pontiac Bonneville Forum - Official home of the Pontiac Bonneville Club.
So, to update, I still haven't found any vacuum leak, and haven't driven the car much, but it seems like I was keeping the P0171 in a pending state.
So, I tried to contact ZZP about the issue, to see it the HV3 or the Stage 1 throttle body might be causing the problem... no response. Is ZZP AWOL?
So, my mother started driving it again, and shes having an issue dealing with the low idle and stalling... and I think that is what finally triggered a P0171 and the CEL.
She had to drive the car on a longish trip (150 miles) to pick me up, and after I starter driving the CEL turned off. However, once I got stuck in some NYC traffic, I was trying to scoot around a stopped car, cutting the wheels hard, and the car might have gotten hung up on a road imperfection, but it didn't seem to want to move... when it did, the car jerked with a BAM! And started moving... I thought I was rearended, but the car behind me was likely too far away.
After another 20 minutes or so, I was back at speed, and I noticed the CEL was back on, and the tranny was shifting hard and surging somewhat at part throttle and it felt like the TCC was sticking on slight decel.
I got to the airport, and dropped my passengers. Alone, I was able to experiement more without scaring my passengers. I found that by driving the car like I stole it, it ran fine... so this was clearly a part throttle/light decel issue. After the car was cooled off, I cycled the ignition three times and the CEL turned off. I drove 150 miles to my "other" home without incident.
I read the codes... P0171 and P0742... which I kind of suspected, and I figure the tranny was potentially in limp home mode. Driving the car about since, I noticed the car might a bit of a shutter after mid-throttle upshifts but no CEL. I'm not sure if I'm being paranoid however, since I have driven alot of other vehicles instead of the Bonne in the last 6 months.
So, I'm still trying to figure the problem. I tried revving up the car in park, and I noticed it seems to not rev above 4000 rpms. When driving, however, it regularly hits 5500. I thought that odd.
Also, I've noticed with the new alternator, when the car idles (barely) at 700 RPM, the alternator is not charging... dipping into the red zone. What RPM _should_ a moderately (closed loop) warmed up Bonne idle at? At what RPM should the alternator start actually charging? It seems like this alternator tdoesn't charge up until 1000 RPM. I was thinking this low voltage condition might be aggravating a sensor or the PCM, causing the idle problems/cold stalling/CELs.
The car now has a bit over 1000 miles since the big overhaul (194.5K instead of 193.2K). Neither of these problems ever came up before the overhaul.
Thanks for reading all this, and I appreciate any thoughts.