I have a 1997 Dodge 1500 2WD with a 5.2L. I have had a vacuum leak for quite a while and i cannot find it. Upon startup in temps. less than 80 degrees I can hear a hissing coming from the engine until it warms up. My cruise went out a little while ago so i searched for a vacuum leak and found it under the battery tray. This fixed the cruise and "wild vents" i was having problems with. I thot everything was fine until the next cold morning when it still was hissing. I have sprayed all vacuum lines in engine bay and around throttle body with carb cleaner and could not find a leak anywhere. Now i am not sure where to look. Also i am now getting a multiple misfire code during high acceleration (pulling trailers). I figure that is because of the vacuum leak. Any help would be appreciated!!

 

How's your plenum gasket?

 

Misfire might be due to bad plenum. Read the stickied thread at the top of the forum.

As for the hissing, make sure the gasket for the air cleaner is there. If that's not the case, and you've sprayed around the intake, the iac may be to blame.

 

I did the Huges plenum kit about 2 months ago.

 

And is it holding up? I had to do mine twice because it was installed wrong the first time. Have you changed the distributor cap and rotor recently? Test the coil too.

 

I replaced the cap and rotor when i did the plenum. I assume its holding up fine. Its not using oil like it did. Havent checked the coil.

 

I had a similar problem. Check your plenum.

 

check that you have the rubber gasket between the top of the throttle body and the air filter. its about $2 at any parts store. also check that the air filter clamp is on properly and tight. its sort of tricky.

 

I replaced the air filter gasket when i did the plenum also. Im pretty sure i got the clamp on correctly but ill check it again.

 

Check your power steering pump; mine has a his.. usually it kinda goes away with increase of throttle; to prove it's it you can take the belt off for a moment crank the engine and listen if it's gone then that's probally it... dont run the truck too long bc your water pump and alt wont be working with out the belt.

Mine does this and despite what some might say; replace the lid; it seems Dodge have this problem with hissing power steering pumps. Ford's whine.. dodge hiss..

Good luck and hope this helps