High idle coming to a stop - JeepForum.com

 
LinkBack Thread Tools
post #1 of 14 Old 12-13-2010, 11:20 PM Thread Starter
outlaw30
Registered User
2001 WJ 
 
Join Date: Sep 2010
Location: AbuDhabi
Posts: 299
High idle coming to a stop

'01 WJ, 4.7L, Quadratrac II, 120k.

Trans and TC seem to be working just fine, smooth shifts, normally idles just fine (I have a P0740 Torque Convt lockup light coming on, but only when I try to accelerate hard from highway speeds, so I don't think the issue is linked).

Problem is, when slowing down and stopping, idle is very high, around 900-1000. Trans shifts down to first with a lunge just as I stop, then after a few seconds, settles down to a normal idle of 600-650 or so. Anybody know what this might be? It doesn't seem normal, as I would expect the tranny to have shifted to 1st a good few seconds before I stop, not as I'm just at a stop, and engine shouldn't still be fighting the stop up around 900-1000 rpm. Trans fluid changed before I got the Jeep a few months ago, only put 2000 miles since I got it, and has been doing it since I got it (hence not sure if its normal). Thoughts please.

outlaw30 is offline  
Sponsored Links
Advertisement
 
post #2 of 14 Old 12-14-2010, 07:05 AM
gdp
Registered User
2001 WJ 
 
Join Date: Jun 2010
Posts: 270
from your description, my GC is the same way, however i don't experience any downshift lunges or issues, my mileage is at 155K. Matter of fact, i don't even really feel a down shift(it dowshifts alot better than a brand new GMC truck i had), but the idle does seem to take a couple of seconds to come down to 650. Mine seems to hang around 800 RPM then come down. But my experience with fuel injected cars (especially automatic transmissions), that this is somewhat normal. So it sounds like your engine is acting normal, but maybe there is an issue with the transmission. I would be alittle concerned about the torque converter fault, if that is not unlocking, it will definitley give you hard downshifts and eventually stalling as you stop.

You may want to clean your IAC valve as a start since it controls idle speed. They tend to get carbon build up.
gdp is offline  
post #3 of 14 Old 12-14-2010, 10:02 PM Thread Starter
outlaw30
Registered User
2001 WJ 
 
Join Date: Sep 2010
Location: AbuDhabi
Posts: 299
Thanks gdp. IAC is clean, and it doesn't act like any of the TPS issues I've read on here either...thats why I need some ideas. Guys??

As for the torque converter, it unlocks perfectly, and I never have come close to stalling (high idle is my problem, nothing approaching stalling). The problem is that it doesn't want to lock up in 5th gear. At speeds above 75, it will 'hunt' between 2200 and 2400, also, when accelerating hard at about 60, it seems to slip slightly, ie more revs, not much more acceleration, and my CEL will come on.
outlaw30 is offline  
post #4 of 14 Old 12-14-2010, 11:12 PM
narnwv
Moderator
 
narnwv's Avatar
2000 WJ 
 
Join Date: Sep 2009
Location: Cross Lanes
Posts: 6,417
Quote:
Originally Posted by outlaw30 View Post
The problem is that it doesn't want to lock up in 5th gear. At speeds above 75, it will 'hunt' between 2200 and 2400
this sounds EXACTLY like a TPS problem. If you do replace it only use a MOPAR part.

~Aaron


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
narnwv is offline  
post #5 of 14 Old 12-14-2010, 11:55 PM Thread Starter
outlaw30
Registered User
2001 WJ 
 
Join Date: Sep 2010
Location: AbuDhabi
Posts: 299
narn, thanks man. Really? everything i've read on here relates to stalling and such with a TPS. You're saying my lockup issue/hunting rpm at speed (throwing code 740, which is torque convt) is just a tps? I hope you're right, I was thinking my Tq Converter was going bad...
outlaw30 is offline  
post #6 of 14 Old 12-14-2010, 11:59 PM
narnwv
Moderator
 
narnwv's Avatar
2000 WJ 
 
Join Date: Sep 2009
Location: Cross Lanes
Posts: 6,417
Mine "hunted" in that rpm range at high speed and a new MOPAR TPS fixed it. It wasn't throwing any codes at all, but from suggestions here I replaced it and it took care of the issue.

~Aaron


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
narnwv is offline  
post #7 of 14 Old 12-15-2010, 12:18 AM
DemonButter
Registered User
2000 WJ 
 
Join Date: Jul 2010
Location: Western NY
Posts: 189
Your TPS could be throwing your RPMs high, low, or out to left field and back. My high rev starts, intermittent near-stall idle (with clean/new IAC), and occasional high speed tranny confusion, all disappeared with nothing more than a new TPS.
Hope your problem is easily solved as well.
DemonButter is offline  
post #8 of 14 Old 12-15-2010, 02:25 AM Thread Starter
outlaw30
Registered User
2001 WJ 
 
Join Date: Sep 2010
Location: AbuDhabi
Posts: 299
thats great news guys, thanks. I hope so too. Have a new TPS ready to go in -- Mopar. For these kinda things, I like OEM.
outlaw30 is offline  
post #9 of 14 Old 12-26-2010, 12:13 AM
hermitlife
Registered User
2000 XJ Cherokee 
 
Join Date: Dec 2010
Location: Carson / San Diego
Posts: 5
could you post back whether the tps solved it once you have it installed?
thx
hermitlife is offline  
post #10 of 14 Old 01-13-2011, 03:36 AM
tonymartin
Registered User
1993 YJ Wrangler 
 
Join Date: Jun 2010
Location: United Arab Emirates
Posts: 1,038
any news on this mate?

93 Renegade|Home made add a leaf (by PO, changing out soon)|Rancho adjustable shocks|31x15 BFG AT's|15" GT alloys|AFE Headers|Red SpiderWebShade Trail Cage|Free Sense of Adventure
tonymartin is offline  
post #11 of 14 Old 01-13-2011, 03:52 AM Thread Starter
outlaw30
Registered User
2001 WJ 
 
Join Date: Sep 2010
Location: AbuDhabi
Posts: 299
Hey buddy. I haven't bothered replacing the TPS yet. Pretty sure its the actual torque converter giving me problems in overdrive. The slight high idle isn't getting any worse, and its not much of a bother.
outlaw30 is offline  
post #12 of 14 Old 01-13-2011, 04:00 AM
tonymartin
Registered User
1993 YJ Wrangler 
 
Join Date: Jun 2010
Location: United Arab Emirates
Posts: 1,038
well we can always throw it on when we do your shocks to test it out if you like? So when will you be wanting to do the shocks anyway? May as well do my injectors whilst we're at it eh? May jump on my fuel pump and rear control arm bushings whilst we're at ie eh? Gonna work us to the bone mate!!! ha ha

93 Renegade|Home made add a leaf (by PO, changing out soon)|Rancho adjustable shocks|31x15 BFG AT's|15" GT alloys|AFE Headers|Red SpiderWebShade Trail Cage|Free Sense of Adventure
tonymartin is offline  
post #13 of 14 Old 01-13-2011, 05:09 AM Thread Starter
outlaw30
Registered User
2001 WJ 
 
Join Date: Sep 2010
Location: AbuDhabi
Posts: 299
works for me, maybe next weekend. I'll call ya.
outlaw30 is offline  
post #14 of 14 Old 06-08-2011, 03:50 PM
machbuffet
Registered User
2002 WJ 
 
Join Date: May 2011
Location: LURGAN
Posts: 10
Hi
Just having a read of your post and I have exactly the same issues re the idle as you come to a stop and the downshift lunge as it shifts into 1st.

Although it may not sound like the usual TPS issues, consider this.

I had idle issues where it would idle at 1100, drop to 650 and do this 3 to 4 times before settling. Same issues with the downshift.
Swapped for another used TPS which appeared to operate fine on another vehicle. Whacky idle issue much better but still the downshift issue.

BOTH TPS tested ok, with both giving .5v at idle and up to 3.8v at wide open, with smooth sweep of the needle in both cases - all as expected.
However, I just decided in the end to buy a new TPS and fit it.
Exactly the same voltage readings but a marked improvement all round in overall.

Idle quality has improved and the 50 RPM bounce has reduced. Smoother idle.
Had also had occasional mild clunk type sensation when slowly accelerating and changing from 2nd to 3rd - that hasn't happened since.
Most noticable though, as I brake and come to a stop, the revs are quicker to reduce to 650 and although I can hear it downshift to 1st, the lunge is all but un-noticable.
I'm crossing my fingers, arms, legs and throwing salt over my shoulder - hopefully it's not a coincidence!!!!
Way I figure it is, for the price of 1/2 hours labour at a shop, you buy a TPS and see how it is - at least you can rule it out.

By the way, I followed the advice on the forum and disconnected the battery. The PCM needs to re-learn the TPS voltage values, otherwise it thinks it still has the same TPS and wil treat the new one like it did the old defective one, with some potentialy whacky results. I left mine for over an hour, while I did some other stuff.
Give it a try - so many of the Trans functions are linked to the TPS that it really should be eliminated early on in ant tranny problems.

Let us know how you get on

Barry
machbuffet is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com 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 e-mail address for yourself.



Email Address:
OR

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.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Jeep Forums Replies Last Post
truck feels like stalling when coming to a stop tommybear67 WJ Grand Cherokee Forum 6 11-02-2010 03:57 PM
Need help with high idle WJ farefax WJ Grand Cherokee Forum 3 10-14-2010 01:28 PM
High Idle At Start Up 04StockGC WJ Grand Cherokee Forum 4 10-05-2010 11:58 PM
WJ: high idle EisBlade WJ Grand Cherokee Forum 8 04-08-2010 06:54 PM
Engine Surges after coming to a stop dogbait WJ Grand Cherokee Forum 1 06-17-2004 07:18 PM

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 On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome