Switching intakes changes rpm? - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > TJ Jeep Wrangler Forum > TJ Tech Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 05-10-2013, 08:18 PM   #1
Jeeper
 
OhSixTJ's Avatar
 
Join Date: Mar 2013
Posts: 1,110
Switching intakes changes rpm?

I went from an AEM CAI to the stock intake and my idle (both in gear with brakes applies and in park) has come up almost 100 rpm. It was hanging around 660-680 and it's not at about 750.

The higher rpm didn't help my lights dimming at idle issue though. Dammit! Haha

OhSixTJ is offline   Quote
Old 05-10-2013, 10:39 PM   #2
Jeeper
 
SeVeReDiStOrTiOn's Avatar
 
Join Date: May 2012
Location: CA
Posts: 768
Sounds like you're getting unmetered air into the manifold from somewhere. Check your throttle body and make sure it's torqued to spec. It could have been loose and when you put the stock intake on the jarring caused a vacuum leak. While you're in that area check all the vacuum lines you might have knocked one loose.

SeVeReDiStOrTiOn is offline   Quote
Old 05-10-2013, 10:47 PM   #3
Jeeper
 
Jeeping it real's Avatar
 
Join Date: Mar 2013
Location: Iowa
Posts: 110
Quote:
Originally Posted by SeVeReDiStOrTiOn View Post
Sounds like you're getting unmetered air into the manifold from somewhere. Check your throttle body and make sure it's torqued to spec. It could have been loose and when you put the stock intake on the jarring caused a vacuum leak. While you're in that area check all the vacuum lines you might have knocked one loose.
I agree. I've been a hobby mechanic for many years, I've never once experienced a stock CAI draw more air than an aftermarket, so I'd guess vacuum leak somewhere. Take a can of throttle body/carb cleaner and spray around vacuum lines/intake manifold. If there's a leak, you'll find it.
Jeeping it real is offline   Quote
Old 05-10-2013, 10:58 PM   #4
Jeeper
 
OhSixTJ's Avatar
 
Join Date: Mar 2013
Posts: 1,110
I didn't touch the throttle body (other than loosening the hose clamp) so I'm pretty sure that's tight. It's not too high. I actually think the RPMs with the CAI might have been too low, now I'm back to normal?
OhSixTJ is offline   Quote
Old 05-10-2013, 11:04 PM   #5
Jeeper
 
C.L.'s Avatar
 
Join Date: Mar 2011
Location: North NJ
Posts: 2,199
Quote:
Originally Posted by OhSixTJ View Post
It's not too high. I actually think the RPMs with the CAI might have been too low, now I'm back to normal?
750 sounds a bit high. Once warmed up i hover around 500 - 600.
C.L. is online now   Quote
Old 05-10-2013, 11:05 PM   #6
Jeeper
 
Jeeping it real's Avatar
 
Join Date: Mar 2013
Location: Iowa
Posts: 110
Quote:
Originally Posted by OhSixTJ View Post
I didn't touch the throttle body (other than loosening the hose clamp) so I'm pretty sure that's tight. It's not too high. I actually think the RPMs with the CAI might have been too low, now I'm back to normal?
You could be absolutely right. 100 RPM isn't extreme, and every vehicle will differ within reason. If you think there may be an issue though, I'd go with the aerosol can trick. I'd say the few bucks would be worth the piece of mind. Good luck!
Jeeping it real is offline   Quote
Old 05-10-2013, 11:19 PM   #7
Jeeper
 
OhSixTJ's Avatar
 
Join Date: Mar 2013
Posts: 1,110
Quote:
Originally Posted by C.L. View Post

750 sounds a bit high. Once warmed up i hover around 500 - 600.
You do? Interesting.
OhSixTJ is offline   Quote
Old 05-11-2013, 11:03 AM   #8
Knows a couple things...

WF Supporting Member
 
Jerry Bransford's Avatar
 
Join Date: Nov 2005
Location: Escondido, Calif.
Posts: 35,392
Images: 2
The RPM shouldn't be any higher, I suspect a small vacuum leak somewhere.
__________________
When you have a choice, buy American.

Jerry Bransford is online now   Quote
Old 05-11-2013, 11:27 AM   #9
Jeeper
 
OhSixTJ's Avatar
 
Join Date: Mar 2013
Posts: 1,110
Anyone know what the normal idle is? I'm at work and don't have the FSM on me. I need to upload that sucker to Dropbox.
OhSixTJ is offline   Quote
Old 05-11-2013, 11:58 AM   #10
Jeeper
 
joeinajeep's Avatar
 
Join Date: Sep 2011
Posts: 198
Quote:
Originally Posted by Jerry Bransford View Post
The RPM shouldn't be any higher, I suspect a small vacuum leak somewhere.
Agreed. A CAI should have zero performance changes to an unmodified engine.
joeinajeep is offline   Quote
Old 05-11-2013, 12:32 PM   #11
Jeeper
 
OhSixTJ's Avatar
 
Join Date: Mar 2013
Posts: 1,110
Quote:
Originally Posted by joeinajeep View Post

Agreed. A CAI should have zero performance changes to an unmodified engine.
We aren't talking performance changes. Just operating changes.

OhSixTJ is offline   Quote
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Download our Mobile App

» Featured Product

All times are GMT -5. The time now is 06:18 PM.


User Alert System provided by Advanced User Tagging v3.1.0 (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.

Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC