high RPM on highway; bad mileage city/highway

[KoG506]

I searched but did not find answer.

When get on highway, It seems like my '00 avy rpm is higher than normal.... 2100~ @ 60 MPH (so @ 70 MPH the rpm will be about 2500~)... and when i take my feet off the gas(while driving on highway) the rpm drop really quick to about 1600~ RPM then less than a second (with foot still off the gas), jumps back up to 2000~ RPM. the highway does not have hills.


The mpg in local driving seems to drop also. the multi-display Avg econ display lower than usual. I also dont race the engine/car. ( i have been driving the same route since a year ago)

my avy is at around 123,6XX mile

I also change the oil and filter every 5k.
Car never been overheated or accident

So does any one know whats goin on? has this happen to anyone?

Please help me!

[BiXLL]

Sounds to mew like your overdrive is either off or not working. When your at highway speed and hit the button does the rpm go up?

[brainpause]

I'm pretty sure that is normal RPM. Same as on my '00 Avy, if I remember correctly.

LC

[KoG506]

Originally Posted by BiXLL

Sounds to mew like your overdrive is either off or not working. When your at highway speed and hit the button does the rpm go up?

Yes, it goes up to 3000+ RPM.

I'm pretty sure that is normal RPM. Same as on my '00 Avy, if I remember correctly.

LC

It don't seem normal because i can hit 30+ MPG (without cruise) easily before i felt the car rpm higher than usual and now it difficult.

And there is a thread and member said that his car is at 1700~ RPM @ 70MPH, that seems normal.

[brainpause]

Ok. I'll try to pay close attention tomorrow on my commute, and post back tomorrow.

Larry

[KoG506]

we have a 2004 sienna and the rpm is not high like the avy. (even though sienna has 5 gears). it gets better mileage and the avy should get better mileage then the sienna.


And I just remembered, When driving or at idle, and i rev up to about 2500 RPM. I hear this loud rattling noise. Like plastic rattling noise. I took the engine cover off, rev it up and the noise is still there. so im thinking its internal.

anyone know what causing this sound? Is it bad?

Ill try post a video later if i can.

[TrailDust]

Originally Posted by brainpause

I'm pretty sure that is normal RPM. Same as on my '00 Avy, if I remember correctly.

LC

Agreed, my 2002 Avalon runs about 2,450 RPM at 70 MPH. There's quite a disparity in the mileage too, with an average of 18 MPG city and 31 MPG highway (at 65 MPH).

[TedL]

Originally Posted by KoG506

we have a 2004 sienna and the rpm is not high like the avy. (even though sienna has 5 gears). it gets better mileage and the avy should get better mileage then the sienna.

The logic of the parenthetical above is backward. The fifth gear lowers engine RPM's, reducing wear and increasing fuel mileage. Thus, a five gear tranny should yield lower RPM at a given road speed...what you're seeing.

[brainpause]

Originally Posted by TrailDust

Agreed, my 2002 Avalon runs about 2,450 RPM at 70 MPH. There's quite a disparity in the mileage too, with an average of 18 MPG city and 31 MPG highway (at 65 MPH).

I checked today. About 2300 RPM at 65 mph, and 3100 RPM at 65 mph with OD off.

Larry

[KoG506]

Originally Posted by brainpause

I checked today. About 2300 RPM at 65 mph, and 3100 RPM at 65 mph with OD off.

Larry

ooh ok.. thank everyone for the replies.

my avalon has 124XXX mileage... i believe its still on orginal factory spark plugs. when do i change them?

[TrailDust]

Originally Posted by KoG506

ooh ok.. thank everyone for the replies.

my avalon has 124XXX mileage... i believe its still on orginal factory spark plugs. when do i change them?

Now.

[Jason.MZW20]

Sounds like the torque converter lockup control solenoid is going bad or you're getting a misfire when the engine runs momentarily rich after letting off the gas.

If the transmission were operating with torque converter lockup, the RPMs wouldn't decrease at all when you let off the gas as it is mechanically linked to the engine via a clutch and locks out the torque converter.

On 4-speeds, lockup occurs at around 55mph, on 5-speeds, it's variable with partial lockup. Full lock occurs at around 40-50mph in 5th gear only, 4th gear is still set to 55-60mph.

[TedL]

Originally Posted by KoG506

ooh ok.. thank everyone for the replies.

my avalon has 124XXX mileage... i believe its still on orginal factory spark plugs. when do i change them?

Don't know your year, but for '99s, the spec for platinum plugs is 60k miles. Plan on changing plug wires as well. OEM set from sponsor Gary/Toy of Newnan is the way to go for the plugs & wires.

Added issue when left in so long is possibility of frozen/seized plugs that rip out threads, requiring helicoil inserts.

[Lansain]

I have 176,000 miles on my '00 Avalon. I find that ~35mph to 60mph I get 2k RPM. Anything over 60, RPMs increase very quickly, and your situation sounds normal. 70mph is ~2.5k RPMs.

[erom43]

I just posted a similar problem for my 2002 with 130K, before seeing your post. I too run about 2600 RPM at 70 mph. My overdrive appears to be working as well since light comes on and RPM jumps when hitting button. I may have original plugs too, but they have been checked a few times. Let me know if new plugs solves your mileage problem.