Rattle/chatter sound 4th and 5th gear low rpms

Hello everyone. I've tried searching and can find a couple threads on this but no fix. My truck when in 4th or 5th gear (automatic) and lightly pressing the accelerator (1000-1500 rpms) will make a metallic chatter sound, almost like it's lugging. This sound will go away above 2000 rpm it seems louder with A/C on. I can't find any loose shields or brackets, and I took off the skid plate just to make sure. I tried switching fuel grades and nothing seems to help. I did take it in about a week ago and the dealership said it was my fuel trim so they adjusted it but a day later the noise is back. on a side note the fuel trim adjustment did raise my MPG from 17 to 20. This is on a stock 2013 trd offroad with 17,000 miles. Any help would be great. Thank you.

 

Since the Dealer adjusted the fuel trim and you had some success ... I Think it means you are getting pre-denotation?? Since your MPG also went up I'd say bring it into the dealer again and have them retry again ...

 

Lube the driveshaft u-joints, perhaps.

 

Thanks guy's for the replies. I put grease through all the ports I could find and it didn't change. I'm set up to take it back on Wednesday. The tech I spoke with said they will flash my software and change out the plugs. He also hinted at an updated firmware coming out soon, but that's all he said.

 

Update!! The dealer fixed the problem turns out the water pump failed. The rattle/chatter I was hearing were bearings failing. I have never had a pump make that sound.

 

What is the warranty on the water pump. I know this is an old thread but I am trying to figure out what my metallic noise is. Toyota technician said it is a normal (lifter sound). I still want to do my own research.

OP no more noise?

Was the water pump failing or it failed? If so did your vehicle overheat?

FYI this is similar to my noise but during acceleration and when I float the gas pedal at about 1500-2500rpm

https://www.youtube.com/watch?v=Tae5LcwXaeI

 

After getting the water pump replaced my noise quieted down a bit. It would only really get loud when it was hot out. The tech said it was starting to fail and he could feel it when spinning the pulley , I never saw the temp gauge rise when I drove. It seems that the pump was only part of the noise I was hearing, It turns out that I had really bad spark knock that was cured with a new software flash. here is a recording I made. http://www.youtube.com/watch?v=ZHGQfHTWh-0
turn your volume up and if your truck makes the sound starting at the :03 mark you have spark knock and should read this thread. http://www.tacomaworld.com/forum/2n...14-feedback-engine-ecm-reprogram-pinging.html

Let me know if this helps.

 

I have the same problem on my 2.7l 5 spd... was cruising on the freeway on 5th gear going about 60 with the ac on and when i would press on the accelarator a little bit it would make the sound you were describing. Doesnt do it in gears 1-3 or when im idling. Any thoughts?