So i have a 05 legacy GT (ECUTEK, datchwerk sidefeeds, fp red…) that idles at a solid 13.0 and runs pig rich in boost. It also has a light hesitation issue and afr fluctuation at around 1800-2300 rpm when cruising with light throttle. I have checked and changed the following things with absolutely zero results.
When cold, the car idles at ~14.7, but once the idle settles it stays at exactly 13.0.
Its on an ancient ecutek tune, and i dont have the cable so i dont really have a way to log it. But i have been checking things with a scan tool and everything seems in order.
Changed:
Front 02 (twice in the last 600 miles)
Rear 02
MAF (cleaned old one and also replaced, no change)
Fixed:
Replaced cracked exhaust manifold (no change)
Fixed a few minor boost leaks (no change)
Engine grounds (no change)
Checked:
Fuel pressure (perfect)
Coolant temp sensor (correct)
Map sensor (correct)
Iat’s (correct)
Baro sensor (correct)
Boost leak test to 20psi (no leaks)
Smoke test (no leaks)
AVCS (looks fine)
Clamped off evap to see if purge valve leaking (no change)
Now heres the weirdest part. It had a very bad hesitation at light throttle, afr’s would go from 11-17 at light constant throttle position. But the idle was good at 14.7 with slight fluctuations. I installed a new denso front 02, and instantly the car started idling at 13.0, but about 85% of the hesitation issues went away and car ran much better in general. This was so confusing to me that i bought ANOTHER front 02 sensor this time from subaru after i checked all that stuff and it made absolutely zero difference.
Im completely at my wits end and am starting to think the tune is somehow corrupted? I have read about issues with the sidefeed injectors, but unable to find many specifics about how they fail. Ive dealt with leaky injectors before and this doesn’t seem like that. Car has zero misfires and if i rev it to 1k rpm it sits at 14.7. Also about 50% of the time it works itself out in boost and will run at 10.7 and feel fantastic.
Anyone have any ideas before i part this pos out?
