Sounded like I had a flat, but I didn't
 

My and a co-worker were cruising back from lunch when a sound appeared. At first it sounded like I was going to slow in a high gear and the engine was getting bogged down, but the tach was up around 2k, so I knew that wasn't it. It really sounded like maybe a flat tire. The sound seemed to change with vehicle speed too. We turned down a residential street and parked under a tree, prepared to change a tire, but all 4 were fine. After looking around, checking tire surfaces, wiggling wheels that might have come loose, etc we decided to drive and see if we could figure out which corner it was coming from. The noise was gone!

Along with the noise, you could feel it in the car. The passenger felt it too.

Totally gone now, no idea what it was.

Theories on what the heck that could've been?

Only thing I can think is something was stuck on a tire and fell off when we stopped.

Maybe there was water in the fuel from somewhere that was causing a backfire, but you burned it all out.

maybe you picked up a stick?

Maybe it was unintended non-acceleration?! OH NOES!

There was a chunk of stick near the car when I got out to look at it. About 8 inches long and not quite an inch thick. It seemed louder than a stick would be though.

Brett

In my Civic, when it rains, water causes the exhaust to touch the bottom of the car and the cooling makes it expand then contract. It's pretty loud and at first thought it was an ABS malfunction or flat tire. This noise also changes with RPMs.

Was it raining?

If not, then I don't know what it was, maybe something just got stuck in the wheel well.

My first thought was that you may have got a rock somehow thrown between the caliper and the wheel; however, when that has happened to me (twice in my life now) it sounds HORRIBLE with screeching as if the wheel were going to blow off.

Describe the sound in more detail.

Sounds like bad gas to me.

I've had a few sticks stuck to the underbody of my car before (live on a dirt road) and it does sound a lot like a flat tire. It's louder than you think it would be because it resonates through the shell of the car. It's definitely the kind of thing that makes you pull over right away and take care of it. That's my guess, especially with the car being so low to the ground it wouldn't take much to pick something up.

I'm pretty sure he knows what bad gas sounds like.

Ripping fabric.

:clap:

And we just had a thread yesterday where folks were saying spare tires are too much weight.

Imagine if this had been a flat tire. He could have just parked it and waited for a flatbed? That's no fun!

Isn't think it was gas, though I did just eat Chipotle. I put the cluth in when I heard it, and the noise slowed down with the car, while the engine maintained a constant idle speed. The fact that you could feel it in the car pretty well was the most troubling.

I really hope it was just a stick!

It was dry, sunny, about 70F today. Going about 30-35 MPH on a paved road when it happened.

Brett

My spare will be in the trunk, on the car, or on the paddock during autocross. I don't need reduced weight for going to the grocery store it to buy dog food :)

Brett

Same here. Except replace autocross with track days and dog food with cat food. :D

Perhaps a stone got jammed into the grooves in the tire tread? Was it a higher pitch sound like something hard hitting cement or pavement? Or was it a low thumping noise?

If the sound went away, then I would say you had some foreign object stuck or caught momentarily somewhere. Things that make thumping noises that are part of the car tend not to go away.. If the noise continued, I would blame loose lug nuts, out of balance tire, bad alignment, a tire out of round, etc.. But none of those things would simply go away, so I wouldn't stress about it.

It was a low thumping.

Speaking of out of balance wheels, one of my wheels has a shload of balancing weights. I'll post a pic when I get home.

It's simple...

http://a0.twimg.com/profile_images/1...aliens-guy.png

It was probably a pedestrian that never seen the FR-S before and grabbed on. You must have lost him when you made the turn. Poor guy!

You're gonna get some hop-ons

I have nothing to contribute except for this popped into my mind when i read the "sound appeared"..

Skip to 15:20

http://youtu.be/DmuMh0FavfE

EDIT: Apparently i can't embed anymore..

I appreciate a good Arrested Development quote :happy0180:

i vote rock in the tire i have had that happen before.

Are you even old enough to ride a bicycle?

I'm too afraid of other people with more car than skill to go to the track. I also have a fear of trees just off the track.

haha. Has someone been watching the magic school bus after bedtime again?? naughty naughty. tv off, its bed time.

OK, this describes exactly what happened to me yesterday.
Since it was pouring heavily, the below 2 theories make sense to me.

So, which one do you think is more plausible? Has this happened again to someone else since?

PS: sorry to dig up such an old post.

So this happened to me a couple of times. Once it was 3 times ask on a row... driving on highway at ~55mph. Heavy vibration and rumbling noise. Stopped, nothing wrong that I could see. Started driving, no noise. About a mile later, noise and vibration return, stop again. Nothing wrong, restart, no noise or vibration. Few miles later, noise and vibration return, no stop this time. Went away in a couple miles. Never did figure it out

Thanks for the prompt reply.

The water in gas thing had me thinking and the only significant event that happened recently was the ECU warning light that lighted up last week but then went away.

I never got to the bottom of it but it did correspond to the day after I changed from premium RON98 to normal RON98 (no additives) maybe I also got water in the fuel from condensation in the pump tank (not from rain), this is a lot of speculation. What fuel do you use?

Apart from that I'd had to blame the dealer for something not well tightened during the 3rd-year revision 2 weeks ago, but I can't fathom how the noise would go away if that was the case. I did bring the car up to the same speed after the noise stopped.

it's probably the road

I do that stretch of highway many times. It was the first time the GT86 did it in that heavy rain, but I went through there again at night (still pouring) in a A3 and didn't notice anything out of the ordinary.

So, probably not.

I had the exact same thing happen to me. Thought I had a flat but the low tire light wasn't on. Pulled over and found a chunk of road tar on one of the wheels. Peeled it off and drove on with no problem.

the simplest explanation is usually the right one. So yeah g0odspeed probably picked up the road tar after you lol

Lol! More than likely!!