when you rev the engine on a jk, why does it take a week for the RPM to drop back down?
how do i get rid of that?

 

It probably has to do with emissions (assuming there is nothing else wrong).

In the later old days, carburetors had a dash-pot to slow the throttle return.

Here is an example:

 

My guess would be that it has a heavy flywheel, thus it maintains its inertia longer.

 

I noticed when I get it up to about 3 or 4 RPMS to get up to speed on highways I have to wait a few seconds to shift or It sounds like im reving the piss out of my jeep with the clutch held in. The the shift is kinda jerky. Def. takes some getting used too.....

 

This drive by wire system is pretty much the standard in new cars today. It is necessary for a traction control system to work. Instead of a cable going directly from the skinny pedal to the engine throttle like the TJs and everything that came before, in the JK you're sending an electrical signal to the computer, which then interprets what your trying to do with your jeep, then in turn tells the engine how fast to rev. So what you get is a delay from the time you stomp on the gas, and a delay when you let off of it.
Its annoying thing to try to get used to when you're coming from an older car, but necessary for traction control. And I think we can agree TC is a good thing on the road.

 

Just out of curiosity, I have to ask:

Nobody else thinks the throttle rate of return to idle is slowed to reduce emissions created by closed throttle engine deceleration? I'm talking just reving the engine, not vehicle deceleration.

It's a principle that has been applied since auto manufacturers have had to comply with EPA regulations.

 

It has a heavy flywheel. As someone else already mentioned, so it takes longer to rev up, and to drop back down.

 

Oh well. I tried.

 

Ronjenx, I agree with you completely. fwiw

 

IMO it is because the 3.8 has a shitty as compression ratio.