epenney
New Reader
4/4/24 11:24 p.m.
Hey everyone so i bought a used 2013 brz about 2 months ago and everything has been fine up until recently when i was driving to work and stalled at a stop sign. since then this has been happening off and on along with a rough and in consistent idle and doesn't seem to be consistent, I've tried everything i can think of to fix it like new airfilter new maf checked for vacuum leaks (i don't have a smoke tester) and I'm just stumped at this point. I've attached some logs in data zap and was hoping I'm just missing something obvious. Any help is very much appreciated:)
https://datazap.me/u/ethanp/log-1712284979?log=0&data=17
ShawnG
MegaDork
4/4/24 11:48 p.m.
High fuel trims mean the system is maxing out the injectors to keep it running.
Check your fuel pressure, could be the pump or filter.
If it's a positive ft, it's adding fuel because it's lean meaning extra air ingested and not accounted for. If it's negative, it's rich and something is adding fuel that isn't metered like a stuck open purge valve or if flex fuel a skewed ethanol content sensor/algorithm/formula.
PS- don't need a smoke machine for vacuum leaks, just an unlit propane torch or brake/carb/tb cleaner. Spray around until the idle smoothed or or increases.
You're both right - it's not enough fuel for the air. Which can be either low fuel supply or an excess of air :) An air leak usually also means high idle speed, so I'd be checking fuel pressure first.
If a MAF didn't fix it, put the old one back on. Unless you got it from the dealer, you are likely to create issues with a non OE part there.
Without seeing the car, my gut instinct is to unplug the upstream oxygen sensor and see if it runs better. Subarus have a failure mode where the O2 reads hard one way and the computer believes it.
With seeing the car, I'd watch the upper O2 current to see the engine was in fuel control, and then see what the downstream O2 was doing. If it was running lean then the uppers current should be a large positive number (uh, I think... i can never remember, and have to back to first principles to figure it out) and the downstream should be near zero volts. If the upstream O2 was reporting wrong then you'd see the upstream reading lean and the downstream pegged rich.
Ranger50 said:
If it's negative, it's rich and something is adding fuel that isn't metered like a stuck open purge valve or if flex fuel a skewed ethanol content sensor/algorithm/formula.
Unfortunately Toyobarus don't come with a flex fuel sensor, so unless an aftermarket system's been added that can be ruled out...
