MPG's not as good as mileage accumulates?

I'd be wondering if your 12v was on it's way out? They generally last 5 years or 80k miles. One common sign they're failing is a steady reduction in fuel economy.

There are many threads and posts on how to check it, but if it reads below 12v after resting overnight, then it's time to replace. Use a multimeter and don't rely on the car or a Toyota dealer to check it for you.

I'm assuming you've not put some heavy winter tyres on or changed the type of oil you use.

 

I'd wonder about tires.

 

i'd wonder about anything that might affect mpg's. our '04 was pretty consistent through 105,000 miles when we sold it.

 

How many km's on it now?<sorry, see 85K

Just trying to think of factors that could deteriorate over time, and beside what's been already mentioned:

Mass Air Flow Sensor getting fouled?

Exhaust Gas Recirculation Valve clogging?

Engine Air Filter clogging? (though I don't think that's much of a factor, with computer control)

Brakes dragging? (feel wheels right after extended drive, see if any feel markedly hotter)

 

carbon on the cylinder heads?

 

Old joke about electric cars: The farther away from home you go, the more efficient, because you are hauling less weight as extension cord.

 

I've taken out and cleaned the pipe you see in the first pic in this link:

Prius III engine knocking at high torque low RPM (solved) | PriusChat

Also explored as far as I could reach with pipe cleaner type implements.

One end of the pipe has a plastic component that has to be removed first, to access the pipe flange bolts: an exercise in patience that'll have you cussing Toyo. I do have torque spec for the bolts, but found it possible to get a torque wrench on some of the bolts, just used reasonable force.

Really not sure if this would impact mpg, maybe depends on degree of clogging. Mine had a moderate amount, and it's pretty low mileage.

 

I have found that in colder weather I get less mpg cause the engine is actually running more to keep itself warm. And in the summer is higher.

 

Age & mileage haven't affected my fuel economy. IMO, that kind of hit is significant. Changing to tires that aren't LRR or a botched ECU reflash have that impact.

Since the temps have dropped dramatically here, have you checked the tp?

 

is that the recall that cost many people 8 mpg's?

 

Did cleaning that pipe help your mileage?

 

Not that I'd notice. It was very pre-emptive too, we're low km's, and accumulations weren't that bad.

 

If MPG suddenly drops, time to inspect and grease brake slide pins. Mine were stuck and lost about 10% MPG on hwy driving. MPG went back after they were unstuck and greased with official toyota rubber grease.

 

AGS Sil-Glyde Brake Lubricant is a readily available aftermarket caliper slide lubricant that'll also work.

 

It may work most of the time, but I did see some posts complaining of sticky pins with sil-glyde. This is why I invested my $10 to get the grease specified by toyota: http://rav4world.com/pdf/T-TT-0132-11.pdf

 

So it's the lithium soap base glycol (rubber) grease (P/N 08887-01206)? Good to know the elusive stuff is available. And thanks for the link!

 

I took off all tires, took all brake calipers off and checked the caliper glide pins. All moved in and out with a little resistance, and the resistance was approximately the same at all wheels. So, I don't have a locked up caliper or unmoving glide pins.

I ran out of time before I could check the EGR tube.

Update: I took off the air cleaner and hose to the throttle body to take off the EGR pipe for inspection. I found it a little dirty inside but no appreciable accumulation of crud. I rinsed it out with alcohol and used rolled up paper towels soaked in alcohol to twist into the EGR valve body and the intake manifold. I got a bit more crud out reassembled the tube.

I looked thru the throttle body butterfly and found oil in the chamber below it. I took some out with paper towels thru the throttle body. What does that oil mean?