Some new noises when coasting

[thepuzzlemaster]

I had a lift kit installed on my van, and since then, I've noticed some new sounds that seem to be related to coasting.

Sound 1:
Before the engine has warmed up, when coasting to a stop from 2nd or 3rd gear, there is a deep rumbling sound. It can get kind of loud, and does in some ways feel like the van is shaking a bit while it happens. It never seems to happen once the van has warmed up though. I'm not sure if this is just some sort of resonance with the new shocks? But it definitely didn't happen before the lift. Sometimes this sound is more severe than other times. Although I'm not sure what causes the difference. Might just be the style of driving based on how many red lights I hit or the speed limit of the streets I'm on before the van has warmed up.

Sound 2:
This sound is really only audible when driving at speed on the highway. When I depress slightly on the gas pedal to coast a bit, I can hear this kind of wooshing sound. It sounds kind of like it's coming from the middle of the van both front-to-back and left-to-right. If I engage the engine by stepping more on the gas pedal it goes away. And if I depress the gas pedal fully, and fully coast, it sometimes goes away from that as well. But also sometimes doesn't. This happens no matter if the engine has warmed up or not. And it happens at slower speeds as well, but it is not nearly as audible at slower speeds.

Anyone have any thoughts what might be causing these?

[originalkwyjibo]

The first thing I would check is driveshaft u-joints. Your lift changed their angle of operation and if they were already a little worn the lift may have pushed them over the edge.

[Headhunter38]

if the u joints check out all right like originalkwyjibo suggested it could just be something to do with the acoustics of the air flow under the van

[thepuzzlemaster]

This was actually my first thought as to what might be going on. That now that there was increased airflow under the van, perhaps the wind was hitting things a bit differently and causing the sound. At least the wooshing sound that happens at speed. I think the way that it's directly related to how much I depress the accelerator makes me think it's something more than that. But this is definitely a possibility.

I looked through an old thread about rumbling at certain speeds, which sounded similar to my sound 1, and in that case, it was cracked air intake hose.
https://www.toyotavantech.com/forum/...ull=1#post4333

So I've got a couple things to check out.