I've recently had two family members cars - a toyota and a scion have no codes and no driveability issues with high (20%+) fuel trim lately. High fuel trim at idle that gets better with some throttle. both cars passed o2 reaction tests and vacuum leak water tests.
Any suggestions on what to look for next? I was thinking of maybe the issue is the beginning of low fuel pressure or dirty injectors. Haven't had chance to check fuel pressure yet but that is where I want to look next.
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