Engine Vibration at 2500RPM

[Iowabaydog]

Hello, I am new to the forum and Toyotas. Just picked up a 97 SR5 4x4 Auto 3.4L 150K miles, to use as a hunting/dog training vehicle. I knew it needed some work as the previous owner just drove and changed the oil.

The one thing I haven't been able to figure out is a loud vibration from 2500-3000 RPMs when under load. Won't do it in Park so I can't see what is vibrating. It sounds like a loud rattle and my thought is exhaust but the engine also hesitates in this band. Runs strong above and below those RPMs with no Vibration. The engineer geek in me thinks I am hitting the resonate frequency of some loose part. I am going to shore up the exhaust tonight to see if that fixes it but are there any other thoughts?

Thanks,
Dan

 

[techno]

Hope you enjoy your new ride. Good luck trouble shooting the vibration, so it happens only when actually driving and not when stationary? You're probably correct with the reso freq, but the engine hesitating is an interesting symptom too.
Keep us updated please.

 

[Iowabaydog]

I pulled off a rusted out hanger that was loose and doing nothing and that seems to have lessened it. It does do it in park as well seems like it is coming from the rear of the engine. My guess is that it may be one of the heat guards on the downpipes from the manifolds but I can't see it vibrating.

I also cleaned the MAF and changed fuel filters and that has helped the hesitation. Might try plugs next, previous owner changed them not too long ago but maybe he didn't use good ones.

I'll enjoy the ride more once I get all these nuicances taken care of and can start working on some fun stuff.

 

[Iowabaydog]

Well the vibrations does seem to be a trashed muffler. It will get replace next week. But the culprit in the hesitation and making the vibration even worse was that the previous owner used cheap single electrode plugs, replaced with the Denso Dual electrodes and it runs like a champ.