About 2 months ago a bought a 2008 4Runner with 17,000 miles. Thus far am really enjoying it. This past weekend was driving around with the windows down and coming from the rear is a sound similar to out of balance tires. It was really close to noise you hear from helicopter blades turning. Couldn't leave the windows down for long, gave a throbbing effect. It seems to begin at about 40mph and continue through 55, then I guess levels off. If the front windows are down and the rear are up, I do not notice it. Also, it is unnoticeable will all the windows up. Was trying to avoid going through the hastle of bringing it to the dealer. I didn't know if maybe if had to do with aerodynamics on this particular model. I have also moved the roof-rack crossrails to the arrow position for least amount of wind noise. Other than tire balancing has anybody incountered this? I have 33psi in my tires.
Also, my dash average miles per gallon display is off by right at 2 mpg. Read higher than when manually calculated. Anyway to calibrate this?
Thanks to all for your input. Bert
Welcome to the boards,
Rather hard to diagnose over the net but it almost sounds like the tread of your tires is what you are hearing.
An "out of balance" tire will be felt more than heard.
What brand/size of tires do you have?
Also, what is the recommended PSI rating on the lable in the drivers door?
As far as the MPG being off on your display, that sounds about right as mine is a little over 1.5 mpg off and I don't know of any re-calibration for that but check with your dealer to see if there is a reflash for the BCM (Body Control Module).
Thanks for the reply, Flash. Currently mounted are Michelen 265/65/17 Crossterrain. Inside of the door indicates 32psi all around. Would that 1psi make that much of a difference? Could it be the rear mud flaps I'm hearing? It's hard to believe that it's the tread on the tires making that much noise, thought these tires were considered quiet, etc. Anyway, I'll reduce the air to 32 and see if that makes a differnence. If that doesn't help, then I'll make an appointment to bring it in let the service manager take a ride with me to get his thoughts. Thanks again. Bert
Bert, while you can reduce the PSI to 32, I personally go the opposite and I run my tires at 35-36 PSI, 2-3 PSI over. A slightly stiffer ride but better MPG.
I'm still guessing the tread even with the Michelen Crossterrain's but let us know what the service dept. finds.
I too tend to lean towards a couple more psi than recommended for the same reasons Flash suggested. I have had the rear windows in various positions. With them all the way up, all's quiet. Once they're down to half the noise can be heard and increases respectively the lower the windows go. I would like some of you who have a 4th generation model, particularly the 2008 to maybe conduct you own un-scientific experiment puttingr vehicle in similar scenarios. Once again it begins at somewhere between 45-50mph and somewhat subsides at a faster speed. Maybe it's wind noise from the window, fender flares, mud flaps, roof rack, tires and who knows what else. I don't typically ride that often with the rear windows down so I could deal learn to deal with this issue, but it something is in some way not up to specs, I want to get it corrected. I appreciate all of your input and curious if anyone else will have the same results while paying attention to wind noise. Bert
I also have a strange noise like that on my wife's HHR. The car rides fine and everything. At about 40 mph, I could hear it more clearly. Sounds like a helo blade. I think it is because of the tire. The two front tires are not the same, one is 15,700 miles old and one is brand new. I only hear it when I release the gas. If I'm on the gas, it disappears. It's really annoying.
Someone posted it earlier above in an abbreviated version. Without sounding condescending to anyone else on this thread that's trying to help you with tires, but have you tried just changing the window position? I've found on a lot of new cars, if you have three windows down, one rear up, you get a horrible resonation from the wind buffeting against the air already in your vehicle. It's incredibly loud and annoying, and can give a headache in a short amount of time. Try rolling down only one rear window. Do you get the noise? Now roll down the other rear window. No noise? I've found that if I have only one rear window down, the noise is there. It's normal- every car I've been in the last few years has done it. I hope that's the problem and not tires- that may be harder to fix...
__________________
Just got a new-to-me 2008 4runner V6 4WD! Which is shaping up to be awesome. I miss the truckbed, but needed the extra inside for work.
Husky-liners throughout, hardwired escort 8500 x50, more to come...
On the '02 4WD TRD Tacoma- arma-coat bedliner, husky-liners throughout, AEM Brute Force Intake, Silverstar Headlights, 12" Sub (stolen!) Alpine 9886, Garmin Nuvi 5000, toolbox, perhaps a lift to come...
I'd be willing to bet money that if you roll down your very rear window (in the hatch) halfway, that noise you hear will go away.
If you want to hear one that is REAL bad, drive a volkswagen golf 4 door and leave the front windows up, roll the rears down and venture your way towards the highway. It'll make your ears bleed!
Thanks to all for your input. Tires are all in good shape psi & tread as well as balanced. So, with a little experimenting, looks like it's the window positions. Primarily the 2 backseat windows. If the rear are down about half-way, the annoying noise returns, but once I lower 1 or both of the front window(even just a couple of inches or so) it "relieves the pressure". Also it can help to lower the back tailgate glass a bit, too. Appreciate all of your suggestions and thoughts. Have a great weekend. Bert
What you are hearing is natural resonances of the vehicle's cabin, with the wind blowing and boucing off the back glass. Think of it like when you blow across the top of an empty beer bottle. Same principle, only much larger volume, creating a much lower resonant frequency. By opening one of the front windows, or lowering the back glass just a little bit changes the inside volume, the natural harmonics, and makes the noise 'go away', or changes the noise considerably.
2008 Strange Noise.
Alpine 9886, Garmin Nuvi 5000, toolbox, perhaps a lift to come...
Linear Mode
