slow return to idle ( i give up! im asking for help)
#18
CF Veteran
Join Date: Sep 2010
Location: Mercer County, NJ
Posts: 12,692
Likes: 0
Received 4 Likes
on
4 Posts
Year: 2001
Model: Cherokee
Engine: 4.0L I6 HO
An old cat can cause a slow return to idle. While sitting still rev your engine to 2k-2.5k and release pedal do this several times.
Also when your letting the jeep warm up in the am does it idle down to 800 when it gets warm.
Also when your letting the jeep warm up in the am does it idle down to 800 when it gets warm.
#19
Newbie
Thread Starter
Join Date: Mar 2012
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee
the idle does seem just a little slower then normal, but not much.
maybe i need a new cat.
#20
CF Veteran
Join Date: Sep 2010
Location: Mercer County, NJ
Posts: 12,692
Likes: 0
Received 4 Likes
on
4 Posts
Year: 2001
Model: Cherokee
Engine: 4.0L I6 HO
my bet its gonna be your main cat and i believe its walker has replacement cats for around $250, you just gotta do a search for them. a failure cat wont throw a code right away. it sometimes throws O2 sensor codes first. see if you can unbolt yours and take a visual in it to see the condition.
#21
Newbie
Thread Starter
Join Date: Mar 2012
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee
cat replaced yesterday.
220k driven to see if it settles.
its ~better~ but still hanging at 1200-1300 rpm when i let off the pedal.
i wanted to say it feels like the tranny is hanging a little, but it does it when i pop it into neutral too.
sigh.
220k driven to see if it settles.
its ~better~ but still hanging at 1200-1300 rpm when i let off the pedal.
i wanted to say it feels like the tranny is hanging a little, but it does it when i pop it into neutral too.
sigh.
#22
CF Veteran
Join Date: Sep 2010
Location: Mercer County, NJ
Posts: 12,692
Likes: 0
Received 4 Likes
on
4 Posts
Year: 2001
Model: Cherokee
Engine: 4.0L I6 HO
Originally Posted by Xjnick
cat replaced yesterday.
220k driven to see if it settles.
its ~better~ but still hanging at 1200-1300 rpm when i let off the pedal.
i wanted to say it feels like the tranny is hanging a little, but it does it when i pop it into neutral too.
sigh.
220k driven to see if it settles.
its ~better~ but still hanging at 1200-1300 rpm when i let off the pedal.
i wanted to say it feels like the tranny is hanging a little, but it does it when i pop it into neutral too.
sigh.
#23
Newbie
Thread Starter
Join Date: Mar 2012
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee
nope, ive heard of seafoam, never seen it before though.
just for ****s and giggles i put the stock injectors back in and reset everything. no changes same problem.
im really really stumped.
just for ****s and giggles i put the stock injectors back in and reset everything. no changes same problem.
im really really stumped.
#24
CF Veteran
Join Date: Sep 2010
Location: Mercer County, NJ
Posts: 12,692
Likes: 0
Received 4 Likes
on
4 Posts
Year: 2001
Model: Cherokee
Engine: 4.0L I6 HO
Originally Posted by Xjnick
nope, ive heard of seafoam, never seen it before though.
just for ****s and giggles i put the stock injectors back in and reset everything. no changes same problem.
im really really stumped.
just for ****s and giggles i put the stock injectors back in and reset everything. no changes same problem.
im really really stumped.
#25
Newbie
Thread Starter
Join Date: Mar 2012
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee
Alright, here we go.
did the cleaning as you posted. didnt actually smoke much but it does idle a little nicer.
Anyway, back to the original problem, its still taking too long to return to idle about half the time:
a few observations:
im starting to think its running too rich, as my tailpipe is black, which would also explain the slow return to idle... So i unplugged the o2 sensor to see if it was swapping between open and closed loop ( which would explain the slightly bouncy needle) but alas, it still hangs.
i was hoping it was a bad ground, but its not.. or at least not there.
help guys, someone has to have another guess.
did the cleaning as you posted. didnt actually smoke much but it does idle a little nicer.
Anyway, back to the original problem, its still taking too long to return to idle about half the time:
a few observations:
im starting to think its running too rich, as my tailpipe is black, which would also explain the slow return to idle... So i unplugged the o2 sensor to see if it was swapping between open and closed loop ( which would explain the slightly bouncy needle) but alas, it still hangs.
i was hoping it was a bad ground, but its not.. or at least not there.
help guys, someone has to have another guess.
#26
Member
Join Date: May 2009
Location: Northern Illinois
Posts: 247
Likes: 0
Received 2 Likes
on
2 Posts
Year: 1997
Model: Cherokee
Engine: 4.0L
You might want to reset the ecu. I had idle problems after a dead battery...it worked for me: https://www.cherokeeforum.com/f2/jee...ocedure-46047/
#27
Newbie
Thread Starter
Join Date: Mar 2012
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee
You might want to reset the ecu. I had idle problems after a dead battery...it worked for me: https://www.cherokeeforum.com/f2/jee...ocedure-46047/
Any electric guru's on here? im starting to wonder why the thing is so sure its running lean and is pumping extra gas in to compensate. my tailpipe is showing me its rich.
it has a brand new O2( and the one before it that i replaces because of all this was probably fine.)
perhaps a slightly goofy ground to an O2, or even the TPS? not enough to throw a code, but enough to play with the sensor readings?
#28
Ok I know this thread is several years old, but I saw it when mine was having issues so its definitely still helping other jeepers out. Mine was having this issue, would take forever to return to a normal idle, especially once it warmed up (like hanging at 1250-1700 rpm before SLOWLY returning back down to 900 or so). Was running too rich and hotter than it should have. When I unplugged my AIC it would return to idle normal when warm but was hard to start. I cleaned that, checked for vaccuum leaks, checked my MAP sensor, still nothing. Turned out to be an easy fix, the temp sensor for the computer on the rear of the block (not the one by your thermostat housing that runs your temp gauge). The wire going to it had rubbed almost completely through. I cut it and put a good crimp connector on, started the jeep, and she runs like new. Just thought I would share so we could have one more documented case that was solved on this issue.
#29
CF Veteran
Join Date: Sep 2009
Location: ☼ Blackhole Sun
Posts: 8,567
Likes: 0
Received 18 Likes
on
16 Posts
Year: My Jeep is a GMC
the temp sensor for the computer on the rear of the block (not the one by your thermostat housing that runs your temp gauge). The wire going to it had rubbed almost completely through. I cut it and put a good crimp connector on, started the jeep, and she runs like new. Just thought I would share so we could have one more documented case that was solved on this issue.
"When I unplugged my AIC it would return to idle normal when warm"
(Idle Air Control)
This is your clue.
Last edited by Turbo X_J; 09-06-2018 at 04:39 PM.
Thread
Thread Starter
Forum
Replies
Last Post
Calikingcrawler
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
8
09-07-2021 07:14 AM
Programbo
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
21
09-26-2015 11:32 AM
cdf43
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
18
09-09-2015 02:47 AM
MidwestNick
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
1
09-04-2015 01:48 PM
australian_expat
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
4
09-02-2015 09:02 PM
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)