Thumping noise at low revs under load

I've driven Toyota trucks for over 30 years and have been very pleased with them. I recently traded in my 1991 extra cab v6 4x4 after almost 26 years of ownership. I traded it for a 2014 Tacoma access cab v6 4x4 with a 6 speed manual transmission about 2 months ago. The truck had about 47k miles when I bought it. It is in very good shape and carfax records showed that the previous owner got the required maintenance done. After a while I noticed that it makes a noticeable thumping noise at low revs (under 2000 rpm) when the engine is under load, like driving uphill. It "sounds" rough, but feels smooth. If I accelerate above 2000 rpm, the thumping noise goes away or is at least very diminished. I can't tell if it's an engine noise, exhaust noise or something else altogether. I've searched here and all over the web and haven't found any definitive answers. Has anyone else experienced something like this? Is it an indication of a minor problem or am I in for some major repairs? I don't know if it matters but I do live at about 6000 feet and drive at elevations varying from about 4000 feet to 9000 feet. Thanks!

 

Check the heat shields on the exhaust are not rotted apart and vibrating

 

Thanks Steves104x4, I will check that out.

 

also check the air box inlet from the fender. the tube vibrates around the hole. some weather stripping or foam will fix it.

 

Thanks desertrunner24, I will look into that too.

 

you got it. mine had a similar thing and when i replaced my factory intake with a trd one the sound went away

 

Steves104x4, I checked the heat shields and they were all in good shape and firmly attached. I may have my mechanic check in case I missed something when I take it in for the next service. Thanks again.

 

desertrunner24, I checked the air box inlet from the fender and I can see that there's some slop. I may work on it this weekend or just let my mechanic deal with it when I take the truck in for the next service. Thanks again.

 

has it had the ping tsb done ?

 

127.0.0.1, I just bought the truck 2 months ago so I don't know if the ping TSB was done or not. Can you point me to information about the TSB? I will look into it, but don't think it applies in my case. I don't hear a pinging. It's more a a thumping or burbling sound. It almost sounds like it has an after market exhaust to make it sound "rougher". But I think the exhaust is stock. Thanks for your reply.

 

https://www.tacomaworld.com/threads/tsb-list-for-2005-toyota-tacoma.7107/

T-SB-0044-14- 07 JUL 14 - Spark Knock Noise

Some 2012 – 2014 model year Tacoma vehicles equipped with 1GR-FE engines may exhibit spark knock (detonation) during light acceleration and/or uphill in hot weather (80 ◦ F or higher). The Engine Control module/ECM (SAE term: Powertrain Control Module/PCM) logic has been modified to reduce the possibility of this condition occurring. Follow the Repair Procedure in this bulletin to improve this condition.

 

Long shot, but driving with the windows open? Sometimes you can get a thumping from the air flow patterns in the cab.

 

Thanks for the info 127.0.0.1

 

baboon, I know the sound you're talking about that's not it. This happens with windows closed. Thanks for your reply!

 

I attach a video camera to the undercarriage when I can't isolate the sound I'm looking for. It's helped me rule out large sections in a short amount of time (like, is this coming from the front or back) and then focus on the smaller spots.

 

Does it sound anything like this? https://youtu.be/uFJx75kTmEw I'm having a similar noise to what you describe and am trying to figure it out. I will let you know what I find out.

 

Did the noise change when you switched to neutral? Sort of sounds like it did. Have you checked your motor and transmission mounts?

 

I haven't taken a good look at those yet. I'll do that next time I'm under there tho! Thanks

Edit: Just checked and the mounts seem like they are still in great condition. Must be something else because the engine barely moves when idling under load. The search continues...

 

https://m.youtube.com/watch?v=Xf6eA5kxe2k&feature=youtu.be

Sounds similar to the problem I had. Mine was the intake snorkel in the front passenger fender. There is a gasket between the snorkel and fender that gets crushed or damaged.

Couldn't believe that a vibration issue on the passenger side fender can migrate over to the driver side pedals. Fixed the gasket and haven't heard it since. My symptoms were more evident with a cold engine.

 

Saskabush, the noise is kind of similar. However, I don't hear it at idle. Only only hear it when the engine is under load, lik when I'm driving uphill. Thanks for the sound clip and good luck with your noise!