Car: 03 wrx 5 spd Pertinent Modifications: bullwinkle stage 2 (85k miles) invidia catless tbe, vishnu catless up pipe. Description of the problem: I've been getting gas at either BP on robbert or costco. I've been getting 25 avg in the winter or summer. About 2 tanks ago I noticed I was getting at best 20 avg. I've been noticing a lot of back firing lately. Recent maintenance or modifications: I have replaced my air filter plugs(1 stage colder NGK) and did an oil change( rotella t6 5-40 ) same oil i've been using for the last 150k. When I did my plugs they looked like 30k plugs no oil, not running rich, not running lean.I was thinking it could be my injectors leaking a bit. Also after I did my plugs my idle vac was dead on 18 inhg before it was bouncing between 18-20. Thoughts?
Did you get tuned for said colder plugs? Colder plugs are going to change some of the dynamics of the ignition cycle. My guess is, your spark timing was set for hotter plugs, and was burning the amount of fuel you were tuned for properly, and when you went colder, your spark timing doesn't jive with the new plugs and you aren't burning all the fuel. My suggestion, get retuned or go back to the plugs you were using before.
nuke sugested a reset of the ecu so thats what ill be trying first. the car boosts and holds boost fine.
