2004 Buick Century (3.1L V6) - P0102 Code/High Idle/Hard Shifting persists after new MAF and battery reset. Advice?
Hey everyone, looking for some insight on my 2004 Buick Century. I’ve been chasing a rough idle, random misfires (P0300), and some pretty jarring "slam" downshifts when slowing down.
The situation: Initially, I suspected the Mass Air Flow (MAF) sensor. I did a bypass test by unplugging it, and the engine smoothed out immediately. I replaced the MAF with a new unit and performed a "Global Reset" (disconnected battery, drained capacitors, and did the full GM idle relearn procedure).
The hard shifting has improved significantly after the reset, but the high idle persists—the car feels like it wants to move faster than it should when I take my foot off the brake. Most frustratingly, the Service Engine Soon light came back on after a few restarts.
Current Codes (via Actron Elite AutoScanner):
- P0102 (Current, History, Confirmed, Pending): MAF Circuit Low Input.
- U1096 (History): Loss of Instrument Panel Cluster Communication.
Troubleshooting performed so far:
- Intake/Vacuum: Verified all intake boots are tight and not folded. All visible vacuum lines on the intake are connected and secure.
- Electrical at Connector: Verified 12V on the Pink wire and a solid Ground on the Black/White wire.
- Reset: 30-minute battery disconnect and proper idle relearn (5 min Park, 1 min A/C on, 1 min in Drive).
Next Step: I’m headed home now to check the Yellow signal wire for the 5V reference from the PCM with a multimeter.
My Questions:
- If I confirm the 5V reference is present on the yellow wire, is it safe to assume this "new" MAF is just a dud out of the box?
- Could a mechanical issue (like a leaking brake booster) cause a P0102 "Low Input" specifically, or is that code strictly an electrical/sensor signal fault?
- Are these 3.1L engines notorious for rejecting non-OEM (ACDelco/Delphi) sensors?
Any help or "hidden" spots to check for vacuum leaks would be much appreciated!