I don’t know if I belong here but I have a pretty rare late model Legacy SpecB with the 3.0 H6, runs great but with some OCD tendencies I can see fuel wear [Long Term] it’s suspended straight -7 percent just at idle – when driven, the trims are fine. It’s strange since Bank 1 is at 0-1%
I’m just trying to see what could be wrong, so far I’m ruling these out
All O2 sensors (I just pulled all 4 and replaced them with Denso OEM high quality ones – a marginal improvement but still a bit high)
MAF – this only affects Bank 2 so MAF is ok plus MAF throttle response is good which shows it is doing it’s job
PCV valve – this makes an audible noise and has been cleaned so assume it’s ok
Engine Coolant Sensor – Coolant is fine, no problems here – also had a coolant change done recently
That leaves a few things to think about to see what is causing a rich idle state in Bank 2
Download leaks?
Vacuum leaks
Bank 2 knock sensor, probably not as the car runs fine
Fuel injector leaking or sticking to Bank 2
Leaking fuel regulator
Spark plugs problem – changed 2 years ago – NGK iridium
Is the EGR valve dirty? Don’t think that is the issue as there is only 1 in H6
Grounding or wiring problem
Milage is 138k and the car is stable with no major issues – sticky talking caliper, CV boots and a wheel hub.
Not many garages have experience with these engines here and I’d be wasting my time taking it anywhere so it’s much better to get some opinions from people here who have experience with these engines.
I have the rotation app and also a Launch scanner which has quite a few parameters that I can pull from the car if needed
Maybe I’m just worrying a bit, I just replaced all the o2 sensors yesterday – maybe I was expecting a quick fix – it might take a while for these cuts to settle down – the sensors I removed didn’t look great at all
happy everyone
