slightly high engine rev?... - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > TJ Jeep Wrangler Forum > TJ General Discussion Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 06-02-2007, 07:19 PM   #1
Jeeper
 
Join Date: Apr 2007
Posts: 181
slightly high engine rev?...

I've had my Jeep Wrangler X 6 cyl 5-speed for a couple months now and haven't had any problems. It currently has 19k miles on it.

*Cliffnotes*: RPM was getting "stuck" at 1250-1500 after sitting in stop and go traffic with the A/C on for 10-15 minutes. After getting out of traffic for a while, the RPM was normal.

On my way home from class today I had a little issue. I was driving along with the A/C on (85 degrees today) and I hit some traffic, bumper to bumper.

After being stuck in the stop and go traffic for a good 10-15 minutes, my jeep started acting a little strange. I would be stopped, start moving in first (my RPM would go up as I pushed on the gas), and I'd have to quickly disengage the clutch to stop, then start moving again. So basically, I think I was holding the clutch pedal down when I'd stop, and hold it for a second or two, then start moving in first gear again.

Anyway, after being in the traffic for awhile...as I pushed the clutch pedal down to stop, my RPM would drop to 1250-1500 and get "stuck" there. Normally, the RPM is at about 750. I'd start moving again and when I'd disengage the clutch the RPM would get stuck again. A couple times it didn't get stuck and acted normal, only to do it again the next time I'd stop.

Finally, when I got out of the traffic it didn't do it anymore. I drove the rest of the way home (about 30 miles), then tried to mimick traffic conditions by stopping and going, but barely moving. I did that for maybe a minutes around the block and had no problems.

I'll find out if it does it again after sitting in traffic for 10-15 minutes.


What could cause the RPM to get "stuck" in this situation???
I didn't get any codes.
I'm thinking maybe the A/C kicking on was causing it, but the RPM were not consistently getting "stuck."
Lastly, if it were something with the gas pedal or clutch, I would think that it would have continued to get "stuck" when I tried to mimick the traffic conditions.

lap49X is offline   Quote Quick Reply
Old 06-03-2007, 01:52 AM   #2
Jeeper
 
Join Date: Apr 2007
Posts: 181
No ideas!?! Weird, right?...

No one else has had a similar problem?

lap49X is offline   Quote Quick Reply
Old 06-03-2007, 07:42 AM   #3
Jeeper
 
cnt487's Avatar
 
Join Date: Mar 2007
Location: Jacksonville, FL
Posts: 173
What year is your jeep?? I have a 98 with quite a few more miles but I did have a similar problem, my RPMs were getting stuck at around 2000 and they wouldn't go down at all, so I took the throttle body off and removed all the sensors that were connected and give it a real good cleaning with some Carb/Throttle Body cleaner and now she's purrin again. Not sure if this is your problem but just wanted to suggest it. It can never hurt to clean that TB. Good luck and let us know if you figure it out.
__________________
98'TJ__2.5__33x12.5 ProComp Xtreme MT__3"BL<<(yea yea, i know)__Stock Suspension for now
cnt487 is offline   Quote Quick Reply
Old 06-03-2007, 07:52 AM   #4
Jeeper
 
4.0l sahara's Avatar
 
Join Date: Apr 2007
Location: shelton,ct
Posts: 2,228
Maybe the idle air valve is getting stuck open.Try cleaning it.
__________________
99 sahara
4.0/np231/ax15/d30/d35
flowmaster40,hpd30 with aussie locker,currie upper joints,4.88's, lca skids,chromo shafts,vanco brakes,d35 with super 35 and arb locker,re 4.5" springs,currie arms,re front uppers,Re shocks in back,walkerevens shocks up front, Re track bars with currie jj joints,anti rock,ss brake lines,re rear sway bar links,jks 1.25" bl and mml,bfg 35x12.5 km2's,craiger soft 8's,ome steering stabilizer,currie hd steering,rockmen front bumper,emp tank skid,lots more too.
4.0l sahara is offline   Quote Quick Reply
Old 06-03-2007, 01:21 PM   #5
Jeeper
 
Join Date: Apr 2007
Posts: 181
Quote:
Originally Posted by cnt487 View Post
What year is your jeep?? It can never hurt to clean that TB.
It's a 2004. I've cleaned a TB before in another vehicle, so I'll try it with this one and see if that helps.

Quote:
Originally Posted by 4.0l sahara View Post
Maybe the idle air valve is getting stuck open.Try cleaning it.
Where is the idle air valve located? How can it be cleaned? Would it be easier to replace it?
lap49X is offline   Quote Quick Reply
Old 06-06-2007, 12:44 AM   #6
Jeeper
 
Join Date: Apr 2007
Posts: 181
UPDATE: Things seem to be running normal, although I notice that the RPM slowly drop after shifting out of 2nd gear and a little in 1st gear. After shifting out of 3rd-5th gears, the RPM drops faster. Am I being critical since now I'm watching the RPM more closely? Probably.

Anyway, where is the idle air valve and is it recommended that I replace it or clean it?
lap49X is offline   Quote Quick Reply
Old 06-06-2007, 06:15 PM   #7
Jeeper
 
Join Date: Apr 2007
Posts: 181
Can anyone explain to me where the idle air valve is?

When I shift from 1st to 2nd or 2nd to 3rd, the RPM hangs enough that as I engage the clutch into the next gear, the gear actually slows the engine RPM. For example, When I shift from 2nd to 3rd at about 2000, the RPM slowly drops down to about 1500 RPM as I'm engaging the clutch. When the clutch is fully engaged, the 3rd gear "pulls" the RPM down to around 1250 RPM.

EDIT: The same thing will happen if I shift at around 2500 RPM.

Someone tell me if I'm actually shifting wrong or something? I've driven a clutch for a while, but never had a vehicle with a RPM gauge.

THANKS!
lap49X is offline   Quote Quick Reply
Old 06-06-2007, 06:41 PM   #8
Jeeper
 
Join Date: Nov 2006
Location: Chicago, IL
Posts: 8,286
Send a message via AIM to Triple88a Send a message via MSN to Triple88a Send a message via Yahoo to Triple88a Send a message via Skype™ to Triple88a
On my 00 TJ the idle valve i think is on the throttle body.. mounted with few torx screws..

I have similar problem on mine.. it idles at 1200ish rpm and then it drops after couple of seconds of idle or sometimes when i kick the gas it drops to regular idle. Wird.

I think its the bottom piece.

Triple88a is offline   Quote Quick Reply
Old 06-06-2007, 06:44 PM   #9
Jeeper
 
Join Date: Apr 2007
Posts: 181
OK, I'm helping myself then...

I found this on another jeep forum:

Quote:
Originally Posted by Skeezer
I have a similar problem. When I'm driving the engine will rev high all on it's own, kinda like the throttle is sticking if that makes any sense. It gets pretty loud almost like an air cleaner sucking in air. I'm gonna take Jerry's suggestion and clean out the air module, maybe that will fix it.
Quote:
Originally Posted by Jerry Bransford
That sounds more like a vacuum leak, or possibly the TPS. I can't see the IAC having any ability to cause high RPMs.
So what I will do is clean the IAC and the TB. If that does not help, I will replace the TPS or Adjust it if there is a way. Lastly, I will check for vacuum leaks.

I'm afraid to ask...
How could I find a vacuum leak or which vacuum line is most likely the problem other than the TPS vacuum line?
lap49X is offline   Quote Quick Reply
Old 06-06-2007, 06:45 PM   #10
Jeeper
 
Join Date: Apr 2007
Posts: 181
Quote:
Originally Posted by Triple88a View Post
On my 00 TJ the idle valve i think is on the throttle body.. mounted with few torx screws..

I have similar problem on mine.. it idles at 1200ish rpm and then it drops after couple of seconds of idle or sometimes when i kick the gas it drops to regular idle. Wird.

I think its the bottom piece.

Have you just ignored it or tried to figure out what might be the cause?

EDIT: Your response is appreciated.
lap49X is offline   Quote Quick Reply
Old 06-06-2007, 06:51 PM   #11
Jeeper
 
Join Date: Nov 2006
Location: Chicago, IL
Posts: 8,286
Send a message via AIM to Triple88a Send a message via MSN to Triple88a Send a message via Yahoo to Triple88a Send a message via Skype™ to Triple88a
I cleaned out the throttle body but thats about it... i had the problem before i bored it out.. pretty much no difference in idle.

I didn't spray inside the air control because i was afraid I'd mess something up if i fill it up.
Triple88a is offline   Quote Quick Reply
Old 06-06-2007, 08:54 PM   #12
Jeeper
 
Join Date: Apr 2007
Posts: 181
Quote:
Originally Posted by Triple88a View Post
I cleaned out the throttle body but thats about it... i had the problem before i bored it out.. pretty much no difference in idle.

I didn't spray inside the air control because i was afraid I'd mess something up if i fill it up.
What do you mean that there was no difference in idle?

I'm gonna clean out the throttle body, I just bought Gumout Throttle Body Cleaner.

Does anyone know what the best way is to clean out the IAC? Should I just spray cleaner in it or should I disconnect it and clean it separately?
lap49X is offline   Quote Quick Reply
Old 06-06-2007, 10:23 PM   #13
Jeeper
 
Join Date: Apr 2007
Posts: 181
Triple88a, do you mean that there was no difference between the idle after you cleaned it and then after you bored it out?
lap49X is offline   Quote Quick Reply
Old 06-07-2007, 12:04 AM   #14
Jeeper
 
Join Date: Nov 2006
Location: Chicago, IL
Posts: 8,286
Send a message via AIM to Triple88a Send a message via MSN to Triple88a Send a message via Yahoo to Triple88a Send a message via Skype™ to Triple88a
Quote:
Originally Posted by lap49X View Post
Triple88a, do you mean that there was no difference between the idle after you cleaned it and then after you bored it out?
I opened it up to clean it. It was all black and gui thanks to the cheap K&N stock panel filter that was installed by the previus owner. So i took off the TB to clean it up and found it shrunk in the end for unknown reason.. So i sprayed it all down with TB cleaner and bored it out while i was at it. Basically it idles just like before so i had the high rev issue before just like i do now so no change in idle before vs after the bore.

I did not clean the idle control though
Triple88a is offline   Quote Quick Reply
Old 06-07-2007, 12:45 AM   #15
Jeeper
 
Join Date: Apr 2007
Posts: 181
Quote:
Originally Posted by Triple88a View Post
I opened it up to clean it. It was all black and gui thanks to the cheap K&N stock panel filter that was installed by the previus owner. So i took off the TB to clean it up and found it shrunk in the end for unknown reason.. So i sprayed it all down with TB cleaner and bored it out while i was at it. Basically it idles just like before so i had the high rev issue before just like i do now so no change in idle before vs after the bore.

I did not clean the idle control though
Thank you for your advice. I will clean the TB and also the IAC and see if the problem persists.

I will keep you updated.
lap49X is offline   Quote Quick Reply
Old 06-07-2007, 09:14 AM   #16
Jeeper
 
4.0l sahara's Avatar
 
Join Date: Apr 2007
Location: shelton,ct
Posts: 2,228
Take the tb off intake manifold and clean it.Then take the iac off the tb. It comes off with four torx screws.To clean it spray it with the cleaner and scrub it with a tooth brush or small brush.
__________________
99 sahara
4.0/np231/ax15/d30/d35
flowmaster40,hpd30 with aussie locker,currie upper joints,4.88's, lca skids,chromo shafts,vanco brakes,d35 with super 35 and arb locker,re 4.5" springs,currie arms,re front uppers,Re shocks in back,walkerevens shocks up front, Re track bars with currie jj joints,anti rock,ss brake lines,re rear sway bar links,jks 1.25" bl and mml,bfg 35x12.5 km2's,craiger soft 8's,ome steering stabilizer,currie hd steering,rockmen front bumper,emp tank skid,lots more too.
4.0l sahara is offline   Quote Quick Reply
Old 06-07-2007, 01:16 PM   #17
Jeeper
 
Join Date: Apr 2007
Posts: 181
I'm going to clean the TB as soon as I get the chance. I've also noticed that the jeep doesn't always want to start on the first try. I'm not sure, but could that have something to do with the TB too?
lap49X is offline   Quote Quick Reply
Old 06-07-2007, 05:09 PM   #18
Jeeper
 
Join Date: Nov 2006
Location: Chicago, IL
Posts: 8,286
Send a message via AIM to Triple88a Send a message via MSN to Triple88a Send a message via Yahoo to Triple88a Send a message via Skype™ to Triple88a
Quote:
Originally Posted by lap49X View Post
I've also noticed that the jeep doesn't always want to start on the first try.
like it would crank but it wouldnt start? Does it start hard in the mourning or if it's let to rest for a long time or does it have hard time starting if you shut it off and 5 minutes later you turn it on again?


Mine had the mourning problem so it would take some cranking to start it, later i found a better way to start it.. the problem ended up being fuel pump.. to see if it is fuel pump.. turn the key to on position right when all the dash lights turn on but dont start it the engine or crank it over.. 2 seconds after shut the key off, than turn the key to on again, wait a second or two and then try to start it.. i've heard this method is called priming the fuel pump.. pretty much it builds up the fuel pressure that is lost when you shut off the engine and your pump is bad/weakened.

On mine it started off little here and there no start and in the end before i got it replaced (free=warranty) i'd need to prime the fuel pump like 3-4 times to build the pressure up otherwise it wouldnt start even if you crank it.
Triple88a is offline   Quote Quick Reply
Old 06-07-2007, 10:40 PM   #19
Jeeper
 
Join Date: Apr 2007
Posts: 181
Quote:
Originally Posted by Triple88a View Post
like it would crank but it wouldnt start? Does it start hard in the mourning or if it's let to rest for a long time or does it have hard time starting if you shut it off and 5 minutes later you turn it on again?


Mine had the mourning problem so it would take some cranking to start it, later i found a better way to start it.. the problem ended up being fuel pump.. to see if it is fuel pump.. turn the key to on position right when all the dash lights turn on but dont start it the engine or crank it over.. 2 seconds after shut the key off, than turn the key to on again, wait a second or two and then try to start it.. i've heard this method is called priming the fuel pump.. pretty much it builds up the fuel pressure that is lost when you shut off the engine and your pump is bad/weakened.

On mine it started off little here and there no start and in the end before i got it replaced (free=warranty) i'd need to prime the fuel pump like 3-4 times to build the pressure up otherwise it wouldnt start even if you crank it.
It sounds like maybe the fuel pump, but I will prime it the way you said to. I've noticed it was either in the morning or after sitting 8 hours at work.

I thought about the fuel pump so I've been doing what I thought was priming it by turning the key to ON without starting it, then waiting until the beeps would stop (around 4 seconds) before cranking it. That seems to help most of the time, but once it didn't start the first time I cranked it.

Maybe the fuel pump is starting to go. The Jeep is an '04 with only 19k miles on it, but it sat alot with the 1st owner. I bought it 2 months ago with about 17k miles.

lap49X is offline   Quote Quick Reply
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may 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


Similar Threads
Thread Thread Starter Forum Replies Last Post
rebuilding your engine?? Get Stroked!!! jeeper95yj YJ General Discussion Forum 6 01-01-2014 05:47 PM
D35 strength?? GrnTJ TJ Tech Forum 37 07-31-2013 02:47 PM
Engine running too rich...High Compression Jb1234 TJ Tech Forum 10 11-26-2008 09:20 PM
Engine too rich....High Compression...Please help Jb1234 YJ Tech Forum 0 11-26-2008 05:27 PM
Engine knocking stabs05 TJ Tech Forum 8 08-16-2007 08:08 PM



Download our Mobile App

» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 04:48 AM.



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