Farqui

GS 450H my first Lexus

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I've cleaned the ambient air temp sensor above very gently with a cotton bud and the actual airflow sensors tucked up inside look pretty clean.

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I had a brief drive at lunchtime and logged fuel trims via Torque, not something I've tried before.

I see bank 2 long term fuel trim is on average 7.4% higher than bank 1.

LTFT bank 2 max'd at 16.4% vs 9.4% for bank 1.  20% seems to be the limit where a CEL will be thrown.

LTFT bank 2 averaged 9.1% vs 1.7% for bank 1.

LTFT bank 2 min'd at 9.1% vs -.8 for bank 1.

So bank 2 is adding more fuel, to account for a lean condition, which suggests an issue on just bank 2 right?  More fuel is being added so maybe a vacuum leak, an exhaust leak, bad o2 sensor?

Curiously the short term fuel trims were very similar on both banks.

I need to do a few more tests and add more sensors as I didn't get any o2 voltage readings with this set...so I can't see if a sensor is misbehaving.  I didn't track both  upper and lower exhaust sensors either.

Would appreciate some input from someone more familiar with fuel trim readings and sensor testing.

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The short term trims appear to working as expected, which suggests that the o2 sensors are good.

I can't see any exhaust leaks but it's really tight up at the manifold and the top o2/afr sensor.

I disconnected the Battery for a few minutes which reset the long term fuel trims and then logged a test drive (logging more sensors).  After a few minutes to settle it confirmed that bank 2 is still adding a bit more fuel but less so now, dropped 3% on average. 

I was also able to see the LTFT bank 2 dropped significantly on WOT, which wasn't as obvious before.  This type of drop in over fuelling suggests a vacuum leak, so I've ordered a new inlet/surge gasket.  Reading up online at Toyota v6 issues, a vac issue maybe caused by a duff PCV - which was recently replaced.

I have a decent trip at the weekend, so will see how the long term trims settle down after a few miles/hours.

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