Inukshuk
Rising Sun Member
Part I. Saturday met with a club member (I won't out him here or you may all pester him) who has a genuine Toyota / Lexus reader that handles OBD1.
Goal: diagnose rough cold idle
Opened my old one up (properly from top - NOT THE SCREWS AT CONNECTOR!).
A) A thin strip of metal attched to pin 3 came off somewhere and had pins 2 & 3 contacting. Not sure where that strip was previously attched. That's likely the fuel pump issue. Everything I could bench test per FSM passes. Next will be in truck where I can test voltage at different air flap openings.
B) Pin 5 is no longer securely soldered to the board. Easy enough to fix. I'll dab some solder on the other pins while its open. These pin to board connections are known to fail.
Part II. Sunday put the Blizzak snow tires on the 100 and checked air pressure on the 100 and 80.
Goal: diagnose rough cold idle
- Timing - reads at 5deg. Factory is 3deg. Left alone.
- TPS - tweaked it a bit. No major difference.
- IAC - though mine checked out fine in past, it was reading 12 when should have been around 40. Swapped one on. No change.
- Then my trusty advisor noticed something odd. The fuel pump was running when key was in on position but engine not running. Using EWD he determined three possible circuits. One is Fuel pump relay. Swapped in a spare, checks out fine. Another is in the Air Flow Meter ("AFM") (AFM found in 93 & 94. Mass Airflow Sensor ("MAF") in 95-97). Unplug AFM and fuel pump doesn't run in same scenario (key on/engine not running). Swapped in a spare AFM and fuel pump doesn't run in same scenario. Drove home with this AFM. Two cold starts next two days - idle is smooth. (I also do not have the initial start high-idle, but that's another days' issue)
Opened my old one up (properly from top - NOT THE SCREWS AT CONNECTOR!).
A) A thin strip of metal attched to pin 3 came off somewhere and had pins 2 & 3 contacting. Not sure where that strip was previously attched. That's likely the fuel pump issue. Everything I could bench test per FSM passes. Next will be in truck where I can test voltage at different air flap openings.
B) Pin 5 is no longer securely soldered to the board. Easy enough to fix. I'll dab some solder on the other pins while its open. These pin to board connections are known to fail.
Part II. Sunday put the Blizzak snow tires on the 100 and checked air pressure on the 100 and 80.