Ok I got another issue I've been tring to fix since day one with my 93 cherokee. At times usually under a load, like trying to go uphill or passing someone on the highway, I get a high pitched whistle coming from somewhere, sounds like the back of the vehicle but could be wrong since sound does travel, it sounds just like a turbo spooling up. Any ideas on what or where to start would help a lot, I checked vacuum lines under the hood best I could but since its really only under load it doesn't do much good.

 

Does it have a throttle body spacer? Those whistle under acceleration. Especially the Airaid ones

 

All original no mods at all other than a stereo and speakers lol

 

Any type of cone filter will make that noise as well.

 

Start the engine, and spray ether around the vacuum lines at idle....when the idle goes up, you have found your leak. How is the performance?? A vac leak will decrease your performance...

 

^^This...

That was the first thing that came to mind....mine started that after adding a CAI...

 

No leaks from vacuum lines no real performance difference that I know of but I bought it with this issue so I don't know if it is affecting performance or not I know theres the vacuum lines for the evap system but I can't check them since they run to and from the gas tank

 

how are your fluids... diff, tranny, transfer case if any of these are going out or low on fluid they can make a similar sound. brake booster going can do it too?

 

Tranny is sad to say actually about a quart over full......never checked the diff or transfer case levels

 

As far as the tranny being over filled its been like that since I got it, I was actually hoping for a small leak to lose some fluid lol

 

Is it that woo woo?
Is it loud only in the morning?

 

It sounds exactly like a turbo making boost and its at any time whether its morning cold hot night doesn't matter if I let it warm up or not

 

Is your amp ground good and RCA run away from power ?

 

No amp just head unit and upgraded speakers stock type nothing special....yet

 

I wonder if it could be a leak in the dampner control for your hvac system. That would explain why it is so audible....I dont know...just throwing boogers at the wall to see if they stick.