Hi, I have a 97 4Runner with an engine I just rebuilt. It runs fine, idles fine, no leaks, etc. But in park if you rev the engine it sounds just fine. So the problem is when you drive the vehicle. So if you are driving at say 45 mph and you hit the gas you hear this (what sounds like) whooshing air. If you drive from 0 to any speed you can hear this noise and it gets worse with RPM. The higher the rpm the louder the noise. Could it be an intake leak? I know my maf does not seat real well.

I have heard this noise before, it only did this during cold temps. So when it is cold and you start driving, the engine sounds like it is reving high/or undeload and as you get up to a little speed the sound smooths out. Is the computer doing something to the timing or something when it is cold that causes this noise? Then it smooths out once it gets to a certain speed or temp?
Thanks for any help in understanding this. By the way the transmission does not slip and runs fine.

Mike

 

Sounds like a vacuum leak or air leak of some kind. I would check all the intake piping and the manifold ect.