Lean AFR at idle Fuel trims Maxed out

[ERJ175DRIVER]

Ive hit a wall with this lean issue/ potential vacuum leak.
Car abruptly started running like this on the highway back home
nothing was worked on or touched before this started happening.
car has had all the same parts on for the better part of 4 years and the finished tune included.
put atleast 20+ hours of diagnosing and troubleshooting myself and ive never been stumped like this being in this platform for a decade +

i posted a log and ill list all the things of the done to the car to troubleshoot this maybe someone can suggest something ive overlooked.
Randomly throws P2187 & P0300
Car got a brand new VVT timing kit.
Everything NEW

• • Purge Valve Solenoid
  • MAF
  • Primary o2 sensor
  • Injectors flow tested & cleaned (one injector seal was leaking)
  • Overspeed seals w/ stud kit
  • HPFRV
  • PCV valve and plate gasket (Hose has no tear and no catch can installed)
  • Intake manifold gasket

things ive tested

• • Smoke tested from intake
  • Smoke tested from o2 Bung
  • Boost leak test (only small leak from BOV)
  • Compression tested all cylinders 150psi [+/- 5psi] (Denver high altitude)
  • Brake booster line to manifold capped off

no leaks that were significant...

MAX +25 STFT, LTFT never learns.
Idles at 16-18afr.
Boost vacuum -5 (usually -8psi instead of -10 in Denver)

Im kind of running out of ideas on what could possibly cause this outside the things ive tested and swapped. Feel free to chime in because im pretty much out of ideas. the log makes it look like its genuinely a vacuum leak but i cant find one through conventional means.

 

[brandon19]

If it happened after you had all that work done, it sounds like a wrong sensor may have potentially been installed.

Do you by chance have any logs from when this car was tuned and working as it should? Especially a clean WOT log if possible.

Do be careful or avoid pulls, because if the readings are true and assuming you are on a stock turbo (or really on any turbo it'll matter), you're making 20psi of boost on naturally aspirated AFRs (13.0:1).

 

[ERJ175DRIVER]

If it happened after you had all that work done, it sounds like a wrong sensor may have potentially been installed.

Do you by chance have any logs from when this car was tuned and working as it should? Especially a clean WOT log if possible.

Do be careful or avoid pulls, because if the readings are true and assuming you are on a stock turbo (or really on any turbo it'll matter), you're making 20psi of boost on naturally aspirated AFRs (13.0:1).

nothing was changed before it started abruptly running like this. everything listed was replaced after the fact it started running with +25 STFT and 16-18 afr at idle. its a BNRs3
this was the log for the last revision in 2023.

 

[brandon19]

Okay, so after looking at your data logs, this is what I noticed.

	ENGINE RPM	AIRFLOW	MAF VOLTAGE	BOOST	WGDC	IDC	BAT
2023 DATALOG	5500	300g/s	4.42	19.5PSI	49%	89%	93F
2026 DATALOG	5500	230g/s	4.04	19.3PSI	69%	70%	100F

Comparing the data between the logs, it is obvious there is a massive airflow loss. The boost is identical, however the 2026 data log has 20% more wastegate duty cycle indicating the turbo is working a lot harder to make a similar amount of boost, despite not flowing anywhere near that it did before. The injector duty cycle being lower also indicates that it is injecting way less fuel due to lower airflow readings.

It looks like either a sensor is giving false information (possible MAF) OR there is a leak that isn't being accounted for in the tune.

So I would double check you have no leaks before the turbo and I think you should triple check for boost leaks (after the turbo), maybe the BOV is venting during WOT without realising.

Maybe someone else could chime in to give some insight on it with the data I have shown.

 

[ERJ175DRIVER]

Okay, so after looking at your data logs, this is what I noticed.

	ENGINE RPM	AIRFLOW	MAF VOLTAGE	BOOST	WGDC	IDC	BAT
2023 DATALOG	5500	300g/s	4.42	19.5PSI	49%	89%	93F
2026 DATALOG	5500	230g/s	4.04	19.3PSI	69%	70%	100F

Comparing the data between the logs, it is obvious there is a massive airflow loss. The boost is identical, however the 2026 data log has 20% more wastegate duty cycle indicating the turbo is working a lot harder to make a similar amount of boost, despite not flowing anywhere near that it did before. The injector duty cycle being lower also indicates that it is injecting way less fuel due to lower airflow readings.

It looks like either a sensor is giving false information (possible MAF) OR there is a leak that isn't being accounted for in the tune.

So I would double check you have no leaks before the turbo and I think you should triple check for boost leaks (after the turbo), maybe the BOV is venting during WOT without realising.

Maybe someone else could chime in to give some insight on it with the data I have shown.

well to preface the air loss, I think it would be important to note that the 2023 log was at sea level in California. Most recent log I now live in Colorado 5,000ft elevation. that might account for the turbo requiring more WGDC?
I smoke tested it again a different way through the intake manifold from the line on the BOV. Is this normal for the bov to leak like this from the piston and body not the flange.