Renix Low Idle
#1
Junior Member
Thread Starter
Join Date: Nov 2014
Posts: 53
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee
Renix Low Idle
I had another post but I accidentally posted in the wrong place!
Anyway my 1987 Cherokee Chief, 5speed has some idle issues, I have done a lot to try to solve it but I am not sure where to go to next. It idles at about 600RPM cold and if the throttle is hit when cold it goes way down when it brings the revs down almost to I would say 200RPM. When she is warm she idles at about 550 RPM and does not have the rev issue, seems to come down normally. I would love to fix the cold idle issue and bring the idle up in general, 550 is too low! It does move slightly up and down maybe 50RPM or so when just sitting idling
I did have a high idle before (1200) and adjusted the throttle butterfly to stock using Cruisers tips, then adjusted TPS again. Once I did this the idle came down but unfortunately now its to far down. I should mention the PO disconnected the EGR and plugged the vacuum lines, if this is relevant.
Things done:
Any help is appreciated! Maybe it's time to replace the IAC? I cleaned it pretty good with sensor cleaner (carefully I should add) and no matter how much I cleaned it there was some burnt on residue.
Anyway my 1987 Cherokee Chief, 5speed has some idle issues, I have done a lot to try to solve it but I am not sure where to go to next. It idles at about 600RPM cold and if the throttle is hit when cold it goes way down when it brings the revs down almost to I would say 200RPM. When she is warm she idles at about 550 RPM and does not have the rev issue, seems to come down normally. I would love to fix the cold idle issue and bring the idle up in general, 550 is too low! It does move slightly up and down maybe 50RPM or so when just sitting idling
I did have a high idle before (1200) and adjusted the throttle butterfly to stock using Cruisers tips, then adjusted TPS again. Once I did this the idle came down but unfortunately now its to far down. I should mention the PO disconnected the EGR and plugged the vacuum lines, if this is relevant.
Things done:
- Cruiser Renix Tips done: 1,2,3,4,5,6,7,8,9,11,14,18
- Checked and tightened intake manifold/exhaust manifold.
- Checked for vacuum leaks with carb cleaner
- Replaced Plugs and wires
- Replaced Coil with used one due to starting issues
- Replaced CPS, again starting issues
- Compression test results dry cyl1-6: 120,125,125,120,130
Any help is appreciated! Maybe it's time to replace the IAC? I cleaned it pretty good with sensor cleaner (carefully I should add) and no matter how much I cleaned it there was some burnt on residue.
Last edited by monst3r; 03-11-2015 at 11:02 PM.
#2
CF Veteran
Join Date: Aug 2011
Location: Nor-Cal Coast
Posts: 10,489
Likes: 0
Received 17 Likes
on
17 Posts
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
Well, see what others say. My 02 is yea, IAC related. I removed and cleaned mine a few times over an occiacional high idle, then figured out it was actually my connection at the plug. I think the socket facing up got water in there at some point. Sort of hard to see in there! You might try spraying there well with CRC electronic cleaner, work the plug in and out repeat..
"no matter how much I cleaned it there was some burnt on residue" last time I did it I scraped to shiny metal with my fingernail.
The EGR shouldn't be an issue. TPS could be! (maybe double check, engine side of course)
"no matter how much I cleaned it there was some burnt on residue" last time I did it I scraped to shiny metal with my fingernail.
The EGR shouldn't be an issue. TPS could be! (maybe double check, engine side of course)
#3
Junior Member
Thread Starter
Join Date: Nov 2014
Posts: 53
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee
Well, see what others say. My 02 is yea, IAC related. I removed and cleaned mine a few times over an occiacional high idle, then figured out it was actually my connection at the plug. I think the socket facing up got water in there at some point. Sort of hard to see in there! You might try spraying there well with CRC electronic cleaner, work the plug in and out repeat..
"no matter how much I cleaned it there was some burnt on residue" last time I did it I scraped to shiny metal with my fingernail.
The EGR shouldn't be an issue. TPS could be! (maybe double check, engine side of course)
"no matter how much I cleaned it there was some burnt on residue" last time I did it I scraped to shiny metal with my fingernail.
The EGR shouldn't be an issue. TPS could be! (maybe double check, engine side of course)
I did test the TPS multiple times I have it set perfectly to .82 which is 17% of my reference. Wish I just had another IAC to test it with haha.
#4
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,872
Received 1,526 Likes
on
1,238 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Great job so far. No mention of O2 sensor replacement?
I have become an advocate of Tip 27 after seeing the results on the XJ that was used in my write-up.
I have become an advocate of Tip 27 after seeing the results on the XJ that was used in my write-up.
#5
Junior Member
Thread Starter
Join Date: Nov 2014
Posts: 53
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee
I really am tempted to do the c101 connector, might just need to buck up and do it. I've been avoiding it like the plague. Maybe this weekend.
#6
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,872
Received 1,526 Likes
on
1,238 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
It is testable.
Do the C101 elimination first. easy to do.
Trending Topics
#8
Junior Member
Thread Starter
Join Date: Nov 2014
Posts: 53
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee
I did the c101 delete now, well it was fun but it did not help whatsoever still has the same symptoms (low idle and when cold idle goes so low it stumbles, 100rpm or less for a second or so). What is the idle supposed to be? It idles at about 550 but it goes up and down 50-100 over and over, it does smell like it has a slight over fueling, with a small backfire now and again when hitting the throttle but the previous owner put in a glass back exhaust which has a hole in the pipe just before so this is possibly that problem.
Also cleaned the IAT it was pretty filthy, funny enough cleaning it got rid of this weird stumble I had when turning the truck off.
#9
Senior Member
Join Date: Jul 2011
Location: ogden, utah
Posts: 515
Likes: 0
Received 1 Like
on
1 Post
Year: 2000
Model: Cherokee
Engine: l6
Subbed. I wanna see if you fix it. My 89 will bounce off the "0" rpm bump sometimes, it idles so low. Like you said, after it warms up, it's about 600 to 800. The day I bought it I noticed. But it doesn't bother me. I still have great throttle response and it's never actually died.
Is there a reason this is "bad" or you'd have to fix it?
Is there a reason this is "bad" or you'd have to fix it?
#10
Junior Member
Thread Starter
Join Date: Nov 2014
Posts: 53
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee
Subbed. I wanna see if you fix it. My 89 will bounce off the "0" rpm bump sometimes, it idles so low. Like you said, after it warms up, it's about 600 to 800. The day I bought it I noticed. But it doesn't bother me. I still have great throttle response and it's never actually died.
Is there a reason this is "bad" or you'd have to fix it?
Is there a reason this is "bad" or you'd have to fix it?
#11
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,872
Received 1,526 Likes
on
1,238 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
#12
Junior Member
Thread Starter
Join Date: Nov 2014
Posts: 53
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee
#13
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,872
Received 1,526 Likes
on
1,238 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Time to visit O2 sensor.
BTW, I'm proud of you. LOL.
BTW, I'm proud of you. LOL.
#14
CF Veteran
Join Date: Feb 2013
Location: Justin, TEXAS
Posts: 1,802
Likes: 0
Received 2 Likes
on
2 Posts
Year: 1988
Model: Cherokee
Engine: 4.0
At my school(UTI auto/diesel) we have a program called All Data.
It shows basically all the manufacturers specs and tolerances. It also shows recalls and service bulletins.
So for fun one day I decide to look at the bulletins for 88 jeep cherokees. It showed they had a problem with 02 sensors going bad with minimal mileage. I thought this was interesting and thought I would share..lol
It shows basically all the manufacturers specs and tolerances. It also shows recalls and service bulletins.
So for fun one day I decide to look at the bulletins for 88 jeep cherokees. It showed they had a problem with 02 sensors going bad with minimal mileage. I thought this was interesting and thought I would share..lol
#15
Junior Member
Thread Starter
Join Date: Nov 2014
Posts: 53
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee
At my school(UTI auto/diesel) we have a program called All Data.
It shows basically all the manufacturers specs and tolerances. It also shows recalls and service bulletins.
So for fun one day I decide to look at the bulletins for 88 jeep cherokees. It showed they had a problem with 02 sensors going bad with minimal mileage. I thought this was interesting and thought I would share..lol
It shows basically all the manufacturers specs and tolerances. It also shows recalls and service bulletins.
So for fun one day I decide to look at the bulletins for 88 jeep cherokees. It showed they had a problem with 02 sensors going bad with minimal mileage. I thought this was interesting and thought I would share..lol
I will post back with my results in a few weeks!