Just thought I'd throw this out there as I'm struggling with my other car, recently the fuel economy has gotten to the 11-14L/100km or 16-21MPG. We've had the car for about 4 years now, and its always been right at 8-10L/100km before this. (24-28MPG). So a significant drop.
2010 Rogue SL AWD
230k kms on the clock. Owned since 105k kms.
No CELs. No stored codes.
Not running poorly, good performance, acceleration etc.
No funny noises.
Plugs changed last year about 20k km ago.
Air filter is new.
Ran seafoam for a few tanks. Idle has improved. Fuel economy same.
Pretty sure its not a winter gas thing, that usually only affects F/E by about 5-10% or less.
Had an issue last year with the Crank Position sensor, and the ECM power wire. Fixed that. But for a while it was running badly as the CKP sensor harness was shorted. Wonder if running it like this fouled the O2 sensor.
I have an Innova 3100j code reader that monitors the I/M management. It seemed a little hokey at first, but it has indicators for the major engine management systems like EGR, HTR (O2 Sensor Heater), CAT (catalytic converter status)etc. All of these go 'green' after about 10 minutes of highway driving at operating temperature, except for the O2S (O2 Sensors) and EVAP indicators.
Is it possible that my O2 Sensor(s) are getting lazy? Suggestions on what to do? I thought about just replacing the Upstream one, NGK replacement I found for $135 Canadian, which seems like a decent price.
The evap thing makes sense, I would imagine there is a bad actuator in there as when I fill up, the pump clicks off really early and I can usually squeeze at least another gallon and a half or so into the tank. So i don't think my poor fuel economy is based on a bad calculation either, as I do monitor my fuel input vs mileage driven.