I've been trying to track down the cause of my sudden onset of poor fuel economy on my 03 V8 for a lengthy period, been 2 years come to think of it. Although I only drive my 4Runner in the winter and occasionally in the summer so I never dug too deep into the issue.
Before the decrease in economy. I was constantly getting 17-16MPG (14-15L/100KM) which I kept track with Fuelly. Then over a period of a couple months I started to notice a drastic decrease in fuel economy, and for the past 2 years i've been getting about 13MPG (17L/100km).
First I did the obvious, checked air filter, cleaned the MAF, put in fresh iridium plugs, I even ran Redline fuel system cleaner religiously for a few tanks with no improvement. Changed out both front o2 sensors with some aftermarket OEM ones from Rock Auto, made no difference. Then this last summer replaced them again with Denso sensors, again no difference. And perhaps this is placebo, but I noticed my exhaust smelling more rich. Then about a month ago I got a CEL which came up as the left CAT being below efficiency threshold, but with no change in fuel economy. Hooked up the ODB Torque app and graphed the o2 sensors, and confirmed the left cat wasn't working like it should.
Now should a dead catalytic converter be cause for bad fuel economy if it isn't clogged? Or did it die because the engine is in fact running too rich?
Also I will add that the onboard economy computer has always displayed 17-16MPG despite now being inaccurate and burning much more than that. Because of this I am also suspicious if I have bad/partial clogged injectors that I should remove to have clean and flow benched? More so because Toyota didn't put a proper fuel filter on these vehicles (any one know why?) and the mesh sock on the filter is the only means of defense.
Thanks for any insight!
Before the decrease in economy. I was constantly getting 17-16MPG (14-15L/100KM) which I kept track with Fuelly. Then over a period of a couple months I started to notice a drastic decrease in fuel economy, and for the past 2 years i've been getting about 13MPG (17L/100km).
First I did the obvious, checked air filter, cleaned the MAF, put in fresh iridium plugs, I even ran Redline fuel system cleaner religiously for a few tanks with no improvement. Changed out both front o2 sensors with some aftermarket OEM ones from Rock Auto, made no difference. Then this last summer replaced them again with Denso sensors, again no difference. And perhaps this is placebo, but I noticed my exhaust smelling more rich. Then about a month ago I got a CEL which came up as the left CAT being below efficiency threshold, but with no change in fuel economy. Hooked up the ODB Torque app and graphed the o2 sensors, and confirmed the left cat wasn't working like it should.
Now should a dead catalytic converter be cause for bad fuel economy if it isn't clogged? Or did it die because the engine is in fact running too rich?
Also I will add that the onboard economy computer has always displayed 17-16MPG despite now being inaccurate and burning much more than that. Because of this I am also suspicious if I have bad/partial clogged injectors that I should remove to have clean and flow benched? More so because Toyota didn't put a proper fuel filter on these vehicles (any one know why?) and the mesh sock on the filter is the only means of defense.
Thanks for any insight!
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