1999 5vz cali emissions trd supercharged with urd 7th

Torque pro says my car is always in closed loop. Even on startup in the morning. The only time i see open loop is when theres a heavy engine load (such as during hard acceleration, up steep hill, or deceleration).

What could be causing this?

Im gonna start looking into vacuum/exhaust leaks to see why my LTFT are always at 13-14% during idle and very low throttle. Not sure if this perpetual closed loop thing is related

New oem maf, front a/f sensor, denso ik22 plugs, fuel pump, fuel filter, fuel injextors all within last 5k miles. Coolant temp sensor is new and showing nearly ambient temps on startup. This symptom has existed since i got the truck 25k miles ago

Not sure about startup, but the CA emissions 5vz's stay in closed loop nearly all the time. The front AF sensor allows this more than earlier narrow band O2 sensors.

If you have high fuel trims at low load, get to searching for vacuum leaks... though hopefully other supercharger guys can chime in if low load fuel trims are affected much by the SC. On a (close to) stock 5vz, fuel trims should be under +/-5% basically everywhere.

-Charlie

I also have a '99 with Cali emissions. On cold start mine will be in open loop for maybe 15 seconds or so (just guessing, haven't actually timed it) before it goes into closed loop.

In Torque Pro, create a custom PID with this data:
ECU Header: 0
PID: 0103
Formula: A
Min Value: 0
Max Value: 4

When you truck is cold, turn the ignition to On but do not start it yet. Give Torque Pro a minute to start communicating with the ECU. I know it's communicating when I start seeing temperature values register for engine coolant temp, transmission temp, etc. Then start the truck. When PID 0103 is registering "1", it means it's in open loop due to being too cold. "2" means closed loop, and "4" means open loop due to high engine load (as in going WOT). PID 0103 for me typically registers "1" for a few seconds on cold start up, and quickly goes to "2".

thx robb, i tried this and saw exactly the behavior you described

I’m pretty confident my 01 stays in closed loop even after reaching operating temps. The only time I’ve seen it go to open loop is after I step on the skinny pedal and it reaches wide open throttle.

I actually don’t know if my truck is a cali emissions rig or not but yeah. I thought that was normal. I’ll take a closer look at my scan gauge the next time I hop in it

Your emissions is the same as the 99-00 Cali emissions; two catalytic converters and upstream air-fuel ratio sensor instead of narrowband O2 sensor.

1996-1998: All have single catalytic converter, narrowband upstream sensor

1999-2000: Federal emissions has single catalytic converter, narrowband upstream sensor. California emissions has two catalytic converters and wideband upstream air-fuel ratio sensor.

2001-2002: All have two catalytic converters and wideband upstream air-fuel ratio sensor.

Right, I do have an A/F ratio sensor and 2? (I think) downstream o2 sensor.