wrinkly

Hi guys,

Hoping I could get some ideas as to why my afr during idle suddenly turned so rich.

So background history, the car is mostly stock except for intake, full turbo back exhaust, 3 port boost controller and evo 9 metal bov.
It has been driving fine and idles with no issues prior to yesterday when I took the car to get tuned. Made several pulls on the dyno with no issue but after the 4th pull, it started idling weird.
Afr would be around 11-12 and the car sounded like it would bog and stall out. RPM stayed constant around 900. Other than the rich idle the car still drives ok.

Any thoughts would be greatly appreciated. Initially thought it might be a vacuum leak but couldn't find anything and then thought maybe the front o2 sensor was on the way out but at part throttle and cruising afr was stable around 14.7.

punk3rz

Have you actually done a boost leak test or just a visual inspection? I would do a boost leak test just to verify. You could have a coil pack going bad as well. My evo started acting weird at idle but was fine cruising. Coil eventually died completely leaving me running on 2 cylinders so keep an eye out for that as well.