rough idle, code 15, speedometer works - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Wrangler Forums > YJ Wrangler Technical Forum > rough idle, code 15, speedometer works

Rugged Ridge 8500lb Winch w/ Steel Cable $294.99 Shipped OGreat prices on seating!--Oconee Off-RoadOconee Off-Road Now Offering Zone Off-Road Products!!!

Reply
Unread 10-18-2009, 04:43 PM   #1
kornonthekob99
Registered User
1991 YJ Wrangler 
 
Join Date: Oct 2009
Location: Long Island, NY
Posts: 44
rough idle, code 15, speedometer works

ive searched the answer all over this forum but cant seem to figure out exactly what im looking for... someone else had a similar problem but no one ever responded...

i was driving home the other day and as i was cruising in 4th it felt as if i was getting some resistance.. then it would drive normal, and then resist again... on and off... at a red light a realized my idle was very jumpy, going from 1100 to 700 every few seconds or so... i rode my gears up high in order to prevent from stalling out so i could get home... half way home, the misfiring stopped and it drove fine till i got home....

i ran codes, got a 15, distance sensor or circuit...i read that there is the Vehicle Speed Sensor on the back of the transfer case, and the speedometer itself... my speedo works, i CAN see how fast i am going, so thats not the problem... i heard that the air/fuel ratio is also controlled by the VSS so if that part is off, then the jeep will misfire...

my problem now is that i dont know if i have a faulty VSS, and i dont know exactly which part that refers to, there is a sensor and a cable attached to it.. also i read that there is a gear in there... i dont want to throw down 100 dollars and be wrong, what should i check first? any good diagrams for whats going on down there?

kornonthekob99 is offline   Reply With Quote Quick reply to this message
Unread 10-18-2009, 06:02 PM   #2
Mean Max
Don't poke the bear
 
Mean Max's Avatar
1991 YJ Wrangler 
 
Join Date: Jul 2007
Location: Stuart, Florida
Posts: 13,682
Quote:
Originally Posted by kornonthekob99 View Post
ive searched the answer all over this forum but cant seem to figure out exactly what im looking for... someone else had a similar problem but no one ever responded...

i was driving home the other day and as i was cruising in 4th it felt as if i was getting some resistance.. then it would drive normal, and then resist again... on and off... at a red light a realized my idle was very jumpy, going from 1100 to 700 every few seconds or so... i rode my gears up high in order to prevent from stalling out so i could get home... half way home, the misfiring stopped and it drove fine till i got home....

i ran codes, got a 15, distance sensor or circuit...i read that there is the Vehicle Speed Sensor on the back of the transfer case, and the speedometer itself... my speedo works, i CAN see how fast i am going, so thats not the problem... i heard that the air/fuel ratio is also controlled by the VSS so if that part is off, then the jeep will misfire...

my problem now is that i dont know if i have a faulty VSS, and i dont know exactly which part that refers to, there is a sensor and a cable attached to it.. also i read that there is a gear in there... i dont want to throw down 100 dollars and be wrong, what should i check first? any good diagrams for whats going on down there?
Your '91 (like my '91) is a bastard child.

It DOES have a VSS signal generator mounted in the T-case that feeds a VSS signal (8 pulses per revolution) to the ECM for engine management purposes.

It ALSO has a speedo cable that mechanically operates the speedometer. This is why you can get a fault code for the VSS signal & still have a working speedometer.

Max
__________________
Click here to see all of my different albums on Photobucket.
Choose any album to see all of my pics!


Quote:
Originally Posted by UltimatE View Post
Max has a picture of every Jeep part ever made.
Quote:
Originally Posted by Benderff View Post
No one here knows what they are talking about. You should try Pirate 4x4 they will be happy to help you.

There is no situation that cannot be improved with a small but well-placed explosive.
Mean Max is offline   Reply With Quote Quick reply to this message
Unread 10-18-2009, 06:28 PM   #3
idaholtby
Registered User
1991 YJ Wrangler 
 
Join Date: Apr 2008
Location: Meridian, Idaho
Posts: 2,554
Check the electrical connection for the VSS output to the ecm. If good, you lilely need a new sender. Like MeanMax said, the '91 is an odd duck. Here is a picture if you are unsure...
1991vss.jpg  
idaholtby is offline   Reply With Quote Quick reply to this message
Unread 10-18-2009, 10:41 PM   #4
kornonthekob99
Registered User
1991 YJ Wrangler 
 
Join Date: Oct 2009
Location: Long Island, NY
Posts: 44
o well thats good that my speedo sstill works i guess haha...

yea thats the part i was looking at, i disconnected the sensor connection and replugged it in... am i testing its ohm reading? not sure what i am looking for.. i am just using my pop's car for the time being to avoid getting stuck till i have a moment to look into it further
kornonthekob99 is offline   Reply With Quote Quick reply to this message
Unread 11-10-2009, 01:59 PM   #5
kornonthekob99
Registered User
1991 YJ Wrangler 
 
Join Date: Oct 2009
Location: Long Island, NY
Posts: 44
so i replaced the part... and added an o2 sensor, which was not on the car when i bought it.. it drives better and a lt smoother for the most part, but there are still moments where the car will run rough, and chug chug on me, like its misfiring... not sure if it could still be the parts the just replaced... it wouldnt make sense... i am guesing maybe its al the deposits left in there that just need cleaning out from all the years it probably ran rich from no o2 sensor... any thoughts? ill run codes later again
kornonthekob99 is offline   Reply With Quote Quick reply to this message
Unread 11-10-2009, 02:01 PM   #6
rustywrangler
Got my eye on you.....
 
rustywrangler's Avatar
 
Join Date: Apr 2005
Location: Syracuse, NY
Posts: 18,616
Time for a tuneup probably if you were not running an o2. At least plugs and oil change.
__________________

Congenital Heart Disease is a reality for me, BOTH of my children have it. Please read up and become aware for future generations

Lydia Ann-Acquired 08/05/05 Open Heart surgery 08/10/05
Jacob Patrick-Acquired 01/17/08 Open Heart surgery 02/15/08
rustywrangler is offline   Reply With Quote Quick reply to this message
Unread 11-10-2009, 04:30 PM   #7
MJMPC
Registered User
1991 YJ Wrangler 
 
Join Date: Nov 2008
Location: Elizabethtown, Ky.
Posts: 3,070
Did you clear the codes ?
__________________
MIKE

http://www.dav.org/

MJM Powder Coating
Elizabethtown Ky.

http://www.cityprofile.com/
MJMPC is offline   Reply With Quote Quick reply to this message
Unread 11-11-2009, 06:23 PM   #8
kornonthekob99
Registered User
1991 YJ Wrangler 
 
Join Date: Oct 2009
Location: Long Island, NY
Posts: 44
i gave the car a tuneup when i bought it about 4 months ago, it def needs an oil change now... an i did leave the battery unhooked for a while and then i installed those parts but i havent had a chance to actually see if they cleared, im gonna have to check later
kornonthekob99 is offline   Reply With Quote Quick reply to this message
Unread 11-22-2009, 06:01 PM   #9
kornonthekob99
Registered User
1991 YJ Wrangler 
 
Join Date: Oct 2009
Location: Long Island, NY
Posts: 44
finally got a chance to change rotrs nd pads, and while i was at it, i checked codes again... i am getting a 21.. i had cleared the codes for sure because i was getting codes for the intake sensor and for it running rich and for the speed sensor before but now its only the 21... still confused as to why... i just installed an o2 sensor.. what shoul i check?
kornonthekob99 is offline   Reply With Quote Quick reply to this message
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.
Note: All free e-mails have been banned due to mis-use. (Yahoo, Gmail, Hotmail, etc.)
Don't have a non-free e-mail address? Click here for a solution: Manual Account Creation
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


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.