Bad Fuel symptoms
 

MY93 import wrx
Car has been running sweet, fantastic pickup etc, then
need fuel- fill to brim with optimax and less than usual
millers,(plugs have been coking up with 1 per tank)
After a few miles car is not running as well and stuttering
4-5k revs.
All coils,plugs etc new.

can a bad batch of fuel cause this? Is ecu retarding to compensate?
Or is the cut back on octane booster causing it, or both.

Would appreciate thoughts. before having to check solenoid etc.

WW

Is the exhaust blacker than normal? May be a nackered 02 sensor.

Whats your MPG?

MB

MB

Just had new lambda sensor so emisions ok.