I have a 89 cherokee 4.0 i have a whistling noise i can't get rid of. here's what happens
I start the engine cold, after 2-3 minutes i start to hear the whistling noise. as the engine warms up it gets louder and louder after the engine gets to full operating tempature the noise starts to go away. and the rest of the day no noise. it is definatly a vacuume leak noise. when it happens i hit the gas it changes pitch. it sounds like it is coming from the throttle body. i replaced the TB base gasket. and the EGR valve&gasket. i replaced all vacuume hoses and tubes. any one have this problem or have any ideas what to do now?
thanks in advance

 

Are you having any drivability issues? Have you opened the hood while it is running to try to find it? Is there a throttle body spacer on it?

 

No Drivability issues at all. i have opened the hood when the noise is there but it only happens during warm up from a cold start. i even got a olt stethascope trying to pin point the noise and it is loudest around the throttle body area.

 

Check to see if your intake manifold bolts are loosening up.

Also, a can of throttle body cleaner sprayed around the suspected areas will tell you when you hit the leaking area as the idle will suddenly change.

 

you my friend have a loose intake manifold bolt. a jeep i had did this once. it was the very last bolt closest to the firewall. it doesnt even sound like a whistle really does it? its more like a beeeeeep. this is what had me confused cause it had me thinking it was electrical. good luck hope this helps

 

what he said lol

 

I beat you to the draw this time! LOL.

 

Touche lol

 

Sub'd.... Mines doing the exact same thing... I'll try tightening all intake bolts as well, anyone know the torque specs?

 

Snug is good. I think it's about 14 ft/lbs.

 

Awesome, hopefully that's all it is, its no big deal really, jeep still runs like a champ, wether its whistling or not.

 

Tighten them to 15lbs............

 

Just Wanted to say Thank you! it was the last 2 closest to the firewall. top bolt and underneeth the nut all the way at the very end.

 

Did you have to take anything out of the way to get to them? I think Mine might have a slight leak in it also.

 

Nope top one i tightened with a 14mm socket on a swivel with 2 long ext bars just to make it easy. the bottom one 14mm box end wrench. that one was not easy i had to reach up from the bottom lying on my side