All the Mass Air computers have VSS as a factory installed sensor. If it is missing or non-functional, it sets code 27 or 29.
Mass Air conversions may or may not have the extra wires run depending on how well the conversion was done.
Thanks! I figured a bad VSS would set off a code, but I'm not sure I can rely on my problem setting off a code. Would a bad or weak sensor always trip a code???
I'm not sure what my next steps are here. I summarized what I've done to date and what my issue is.
Issue- runs great except at a stop- RMPs rev up and down quickly from 300 to 1200 on the verge of stalling
Repairs so far:
- Recent O2 sensors- 3 wire OEM
- Recent fuel filer
- New plugs and wires
- Timing 12 degrees
- New IAC
- New ERG
- New ACT
- New TPS- set .94
- New Temp sensor
- New 65mm BBK throttle body and spacer
- No vacuum leaks
- No exhaust leaks (at least from O2 sensors to engine)
- Fuel pressure good
- Engine vac good
- No codes with engine off
- Codes 41 and 91 running (still can't figure these out)