AWD issue at ~40mph

[Bedlam]

I recently picked up a higher mileage 2006 (136k) AWD. The car is an immaculate one owner in great condition. The one issue i have noticed is around 38-41mph when in high gear (OD i think), the engine turns around ~1500 and it seems to lug the motor. I have only have stick 1zz cars up until now so i am not used to how the auto works. The car has a low frequency vibration like i am lugging that car along at idle speed in gear.

It's not a rotational vibration or anything crazy. it sounds and feels identical to lugging the motor in gear on a standard car. is there a dead spot in the acceleration of these cars other than AWD's being pig slow?

Trans fluid looks good and any speed/gear above or below this speed/gear combination is smooth as silk and the car shifts like new. Anyone hear of this before?

[ehoff121]

Congrats on the new to you AWD!

As an owner of a 2005 AWD, I consider this the "mileage sweet spot". The Vibe is at cruising speed, i.e., not accelerating or accelerating very slowly, thus there is no need for higher rpm. If you press harder on the accelerator, the Vibe will drop gear and rev higher again.

What you describe is normal and it seems you have a light touch on the gas

[Bedlam]

Congrats on the new to you AWD!

As an owner of a 2005 AWD, I consider this the "mileage sweet spot". The Vibe is at cruising speed, i.e., not accelerating or accelerating very slowly, thus there is no need for higher rpm. If you press harder on the accelerator, the Vibe will drop gear and rev higher again.

What you describe is normal and it seems you have a light touch on the gas

hrm, ok. I didn't see that coming. I just wasn't a fan of the low frequency din in the passenger compartment that comes with the lugging notion of the engine. It just felt like an unhappy sound, though i could find nothing else wrong. I guess it will just be something to live with on the back roads when it happens. It is only during those 3-4mph in OD and it is easily repeatable. I have been triggering the downshift to avoid it when i get into that range, and letting off again once i crest 43mph to settle it back down into smooth sailing again.

[Salsa Guy]

Mine does the same thing. If going up and down hills at the 35-42mph I just turn off the OD. It's really an issue with the shift scheduler. At 45mph I don't have a problem. Many have with the 4WD/AWD have the same complaint and doesn't appear the FWD cars have that issue. It may have to do more with the additional weight and load with the AWD/4WD system

[ehoff121]

I have been triggering the downshift to avoid it when i get into that range, and letting off again once i crest 43mph to settle it back down into smooth sailing again.

If going up and down hills at the 35-42mph I just turn off the OD.

That low growl is the sound of fuel economy!

By accelerating or turning off Overdrive, it's consuming more fuel for the sake of noise reduction.

It's just mindset. If you can think of it as money staying in your pocket, it might not bother you as much.

[Bedlam]

I have been triggering the downshift to avoid it when i get into that range, and letting off again once i crest 43mph to settle it back down into smooth sailing again.

If going up and down hills at the 35-42mph I just turn off the OD.

That low growl is the sound of fuel economy!

By accelerating or turning off Overdrive, it's consuming more fuel for the sake of noise reduction.

It's just mindset. If you can think of it as money staying in your pocket, it might not bother you as much.

well, lets just be clear about one thing. I am not new to engines and basic physics. Lugging a motor (or anything) enough to cause an abnormal vibration is not healthy in the long run. Also, have the motor or drive-line creating a noise and low frequency vibration is not saving fuel because it is wasting energy to do that and send it through the car instead of getting to the ground. Good mileage means that, the energy produced by the motor is transmitted to the wheels with as little wasted as possible due to drag, heat and vibration. Around 45-55mph is truly the sweet spot for these cars and gearing, i am just trying to get to the bottom of why that 4mph window causes the lugging. These motors really only lug around 1k rpm and lower while loaded in gear and during the 250-300k miles i put on the previous 2 cars, i know this for a fact. I imagine that this issue many of us see is due to either transmission programming or possibly something in the torque converter or something when it is on the edge of a gear with a very light load.

would still be nice to get to the bottom of it at some point. I am not much for accepting problems for what they are, just because a lot of people deal with them.

[Salsa Guy]

I have been triggering the downshift to avoid it when i get into that range, and letting off again once i crest 43mph to settle it back down into smooth sailing again.

If going up and down hills at the 35-42mph I just turn off the OD.

That low growl is the sound of fuel economy!

By accelerating or turning off Overdrive, it's consuming more fuel for the sake of noise reduction.

It's just mindset. If you can think of it as money staying in your pocket, it might not bother you as much.

I run premium gas and have a supercharger and still get 27mpg as a DD. 32mpg driving highway doing 75+. Lugging the engine/transmission is more than just a noise and vibration, it means something something isn't right and can cause damage. Yes the 4WD/AWD have that problem but I've learned to "feather" the throttle or turn off the OD.

[creekhed1]

I used to own an 03 AWD and mine did the EXACT SAME THING! Its basically bad design in the gearbox! At that speed the engine is at too low an RPM to comfortable keep the car in motion and the result is lugging.
Im SURE Toyota/Pontiac engineered the box for economy at this speed and while it gets great mileage, it lugs at about 40. Turn off the OD, speed up, or ignore it. lol