Flutter Noise while Accelerating

I've searched the interweb extensively about this annoying noise that my 1999 Tacoma 2.7L 4x4 makes when accelerating.

The best way I can describe the noise is that it sounds like something is fluttering in the exhaust or engine. Almost sounds like something fluttering in the wind.

Only happens under acceleration. When accelerator is not pressed it immediately stops.

I recently had the exhaust manifold replaced due to the typical cast iron crack in the stock manifold.

Any ideas what would be causing this noise? It also seems to affect performance in my opinion but it may not that much.

Thanks,
Brandon

 

I would first go back and make sure everything is tight. All nuts, bolts and stuff like that.

 

I'll check those

 

there are 2 rubber idolators that keep the exhaust heat shield/lower intake system separated. If not those, I would start by examining the air filter housing... take the filter out/off and see if it is seated properly and the pieces go together correctly or something is broken/cracked, clamps are tight etc.

 

It does have an airy sound to it, so I'll check the air filter housing and tubing to the throttle body as well.

I'll look under the truck at the exhaust too, the guy that replaced the manifold did drop the entire exhaust while he was doing the repair to check for other leaks.

 

I checked the air filter housing and replaced the air filter (needed it anyway) and all those clamps and pieces are snug and no apparent leaks or cracks that I can see.

I didn't remove any parts to inspect the bottom (didn't have much time to check that in depth)

I drive the truck every day to work, so this morning I still hear it while I'm accelerating.

Also the truck just seems to struggle with the slightest incline on the road. And I mean the SLIGHTEST incline. I would expect the truck to have a harder time with steeper inclines, but around my area. the degrees of incline aren't drastic. maybe a few degrees

 

OK, it seems the easy and obvious has been looked at. I am wondering if the catalytic convertor(s) have fallen apart. Banging on them with a rubber mallet and listeneing for rattles is one way, the other is to take them out and look. A good muffler shop can take a look also. They can put a back-pressure device on the exhaust to see if it/they are broken apart.

 

I've also thought the same about the Cat. I thought about buying a MagnaFlow direct fit Cat to replace it, but didn't want to drop dough on that yet if it isn't the cause.

 

Had the Cat replaced with a universal fit MagnaFlow, noise is still present under acceleration (it sounds like a mixture of noisy lifters and a leaky exhaust header in my mind) 90% of the noise is from the engine bay of course.

I just replaced the valve cover gasket as the factory gasket had a leak near rear passenger side corner of the cover. I also replaced the spark plugs while I was at it. One of the old ones was shot, couldn't even get the gap tool in it.

Anyway, any further advice is appreciated.

 

Airy sound is 99% of the time going to be an exhaust leak. Let the truck idle with the AC on (so that the RPM was a little higher) and go underneath. Put your hand around all exhaust connections but dont touch the exhaust obviously to see if you feel any air blowing out of the connections. Also, check the muffler weep hole. It is a common place where the stupid sound can come from. I've had that issue and I know it's there to help keep condensation from building up inside and rusting the muffler out but it was so irritating that I put a self tapper in the hole so it would stop making that noise. Just an idea.

 

I'll check the muffler drain. The truck does have 244k miles on it, it wouldn't surprise me if the muffler also needs replacement. With the new Cat on, the truck does have a better tone to the exhaust due to better flow.

Most of the noise (while driving) is coming from the front/engine area though.

 

it will go away it’s just the changing of the weather mine went away and I don’t hear it anymore. It’s the 1999 Tacoma’s that’s all

 

Lol, I wish the weather change would make it go away, but its been doing this for a good while now.

 

Same mine went away on it own I know exactly what ur talking about it’s been going on for about few months now but it stopped out of know where

 

I'm gonna do the positive pressure method of checking for more exhaust leaks too.

 

But I just recently got a new exhaust so that’s why it probably went away

 

I recorded the noise with my iPhone while driving to work today. Ignore the low end of the audio as that is road noise. You will hear the "ticking" sounds clearly. btw, I was holding my iPhone above my right foot on the accelerator under the dash.


https://drive.google.com/file/d/166oVHnKzJURq9eiu69cOawAOS7rQnSLw/view?usp=sharing

 

My truck started doing this last year after I installed new spark plugs and fuel filter, but it was intermittent and eventually stopped on its own.. I never could identify the cause of it.

 

Again, I wish it would just go away but it won't. Been this way for quite some time now.

 

Did you figure it out? It might just be engine noice coming through the firewall. Check the steering shaft seal. Yours might be toast