Just flashed the V4. Got weird bucking problem at low engine load just after startup. I did'nt reflash the previous V2 rom yet but if anyone can take a look at my log. Here's my analysis so far
- It shows -29 STFT but as soon as I touch the throttle pedal (2%), STFT jumps straight to 0 and AFR drops to 11.25.
- It changes from Fuel System Status 2 to 4 as soon as I give any throttle. 2% throttle normally won't change to Closed loop
- The problem will resolve itself when the car heats up a little bit but I can't get any power from the engine while it's doing that.
- The problem is reproducible. It did not do it on 1st start after flash but after 3-4 runs. Now it does it pretty much every time the engine is cooled down.
- AFR tend to stay at 11.25 for much too long. When bucking lessens, the AFR stays near for a couple minutes. It looks like it comes back to regular values as coolant heats up.
- When coolant is up to 160°F, all seems pretty normal
Can it be the upstream O2 sensor that's going bad?
https://datazap.me/u/robzz/16-v4-02c
Thanks!