Loss of Power and horrible MPG

2008 Tacoma V6 4.0L Long Bed
197,000 miles and has never let me down ONCE!

I have noticed a huge loss of power in my truck and I am only getting 230 miles each full tank
Averaging 11MPG instead of 16

Around the time when I noticed the power loss, check engine light came on for cylinder #5 misfire. I swapped #5 ignition coil with #3 to see if the engine light would change to #3...

I did the “ticking” test on all 6 coils while idle and they all seem to be fine and no engine light has came back yet.

Maybe the coils aren’t sparking to the full potential because of they are getting tired?

Any suggestions would be greatly appreciated

I’ve tried the following:

Replaced Spark Plugs
Brand New Air Filter
Cleaned M.A.F. sensor
Tested all the ignition coils
Checked tire pressure

 

I'm not familiar with that model year, so bear with me. This sounds like fuel starvation. Let me guess: no inline fuel filter, but there's a filter sock in the tank. If that's true, and especially in light of the mileage on that vehicle, I'd do a fuel pump pressure test. And check for vacuum leaks, too. BTW, that CEL might take a bit of time to come back on if the problem cause still exists.

 

Following

 

How many times have you driven it since resetting the CEL? Has to go through a couple of drive cycles IIRC unless it’s a hard fault.

 

It could be the catalytic converter going bad.

 

and I have heard "Clean the throttle body" around here more that once.
at least have a look.

 

I’d suspect, with fuel mileage in that range, your fuel trims would give some insight.
If you or some one you know has a scan tool, maybe look at the fuel trims.
It could multiple things.

 

I’ve driven it at least 3,000 miles since resetting the CEL.


What’s also weird is my fuel gauge stops works below 1/4 tank. I think it may be the sending unit, but I don’t think a bad sending unit would cause bad mpg

 

Could be the VVT-i oil screens are clogged or the VVT-i solenoids went bad. It happens on occasion on the 1GR-FE engines, but there isn't ever a direct code.

You'll pull your hair out chasing this down from what I hear, but the repair is fairly simple. Let me find a write up I saved and post it here once I do.

Found a similar thread but not the one Inhad in mind: https://www.tacomaworld.com/threads/this-is-why-you-need-to-replace-your-vvt-screens.639996/

 

Somebody on here smarter than me can tell you whether the gauge sending unit and the pump are a single unit. If the answer is yes, then I'd say replace the unit and the sock filter, i.e. all 3. Check for good flow while you still have the tank out of the truck, on the small chance the replacement pump/sending unit/sock are dodgy, like some Chinese piece of shit. That test will also verify the fuel line is unobstructed.

 

Could be the VVT-i oil screens are clogged or the VVT-i solenoids went bad. It happens on occasion on the 1GR-FE engines, but there isn't ever a direct code.

^^^^^This^^^^^