1998 Wrangler p0171 and p0138 - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > TJ Jeep Wrangler Forum > TJ Tech Forum

Join Wrangler Forum Today


Like Tree11Likes
  • 2 Post By smooth-rough
  • 1 Post By Digger84
  • 1 Post By epd1210
  • 1 Post By epd1210
  • 1 Post By epd1210
  • 1 Post By smooth-rough
  • 1 Post By epd1210
  • 1 Post By smooth-rough
  • 1 Post By BM3
  • 1 Post By sequel
Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 10-29-2018, 12:03 PM
Thread Starter
  #1
Newb
 
Join Date: Oct 2018
Location: Indiana
Posts: 9
1998 Wrangler p0171 and p0138

Hello All,

I have a 1998 Wrangler TJ 2.5cyl. 87k miles. Was running great, then had a hard start which somehow the brake booster vacuum hose came off ( not sure if it was related). Replaced the hose and then a day later CEL turned on.
Checked the codes and its says p0171 and p0138. Definitely smells like gas, so it is running lean. But RPM's are fine, engine is running good (no hesitate,stumble or stall), just lean.
Ran a can of Sea Foam through it. Started it Saturday, and it blew out the black soot out of the tailpipe.
A friend of mine says this could all be caused by the upstream O2 sensor.
Opinions?

epd1210 is offline   Quote
Old 11-08-2018, 03:04 PM   #2
Jeeper
 
Join Date: Nov 2018
Posts: 30
PO171 scan code is one of most frustrating to diagnose. It could be dozen different things causing it. I'm struggling with that now. Your MPG can go to hell fast, maybe 50% normal. So then you're filling up at the pump twice as often, that can blow up your monthly gas bill. You have to fix it for that reason alone. But also it probably won't pass inspection in most states because its gross polluter. Before you start replacing parts, try STP Ultra 5 in 1 fuel system cleaner. Pour into full tank. You could have some gunk that's clogging your fuel line, and that would clean it up for you cheap. Try disconnecting your battery cable for 1 minute to clear the check engine light, and re-set your code. After that you need to search for vacuum leaks, and apparently its hard to find a good mechanic who can do that. If you have no vacuum leaks, then you start replacing parts, the cheapest first which is the upstream O2 sensor. Report back to the forum your results. We learn from each other brother.
Blondie70 and mimillerus like this.

smooth-rough is offline   Quote
Old 11-08-2018, 06:01 PM   #3
Jeeper
 
Join Date: Apr 2013
Posts: 13,179
Smells like gas is usually rich as lean is not enough fuel for amount of air




Sent from my iPhone using Tapatalk
mimillerus likes this.
Digger84 is online now   Quote
Sponsored Links
Advertisement
 
Old 11-16-2018, 03:15 PM
Thread Starter
  #4
Newb
 
Join Date: Oct 2018
Location: Indiana
Posts: 9
Talked to a mechanic today.. He suggested running Lucas Oil Injector cleaner through it. And resetting the codes. He said although SeaFoam is supposed to clean the injectors, Lucas Oil does a better job. He then said change out plugs before changing the O2 sensor. We will see.
mimillerus likes this.
epd1210 is offline   Quote
Old 12-16-2018, 01:36 PM
Thread Starter
  #5
Newb
 
Join Date: Oct 2018
Location: Indiana
Posts: 9
Finally changed out O2 sensor. . Reset codes. And started her up. Runs smoother and better idle. No CEL light. White smoke but hoping that goes away with time( burning off excess fuel in exhaust)
epd1210 is offline   Quote
Old 12-17-2018, 06:13 PM
Thread Starter
  #6
Newb
 
Join Date: Oct 2018
Location: Indiana
Posts: 9
Well that didn’t last long...... now the codes are p0171 and p0133. The other o2 sensor. Luckily, I ordered it with the other one from Rock Auto.
Will change that one out later this week.
mimillerus likes this.
epd1210 is offline   Quote
Old 10-18-2019, 11:45 AM
Thread Starter
  #7
Newb
 
Join Date: Oct 2018
Location: Indiana
Posts: 9
Well its back the o2 sensor codes. I would think the o2 sensors I bought would last longer than 1 year. Any other suggestions?
mimillerus likes this.
epd1210 is offline   Quote
Old 10-19-2019, 01:09 AM   #8
Jeeper
 
Join Date: Nov 2018
Posts: 30
02 sensor code issue

Quote:
Originally Posted by epd1210 View Post
Well its back the o2 sensor codes. I would think the o2 sensors I bought would last longer than 1 year. Any other suggestions?
Your problem started with brake booster. I've heard faulty brake booster can trigger 02 sensor failure. Inspect everything related to brake booster.

After that run a smoke test. A good mechanic knows what that means. Garage should have smoke machine. It helps identify any leaks in air hoses in your system. These older jeeps have older components. Hoses need to be replaced etc. That could be it. It would be simple cheap and easy to replace leaking hose.

After that exhaust manifold might need to be replaced, that is more expensive and pain in the butt because bolts can be rusted.

Also check the power steering pressure sensor. Believe it or not, replacing that fixed it for me. Some senior mechanics here are skeptical but its a real thing that can trigger 02 sensor failure.
mimillerus likes this.
smooth-rough is offline   Quote
Old 10-21-2019, 10:30 AM
Thread Starter
  #9
Newb
 
Join Date: Oct 2018
Location: Indiana
Posts: 9
I hadn't thought of my power steering sensor. I have noticed the last 5000 miles, I am leaking power steering fluid. And it does rev up when idling sometimes too. Worth a look most definitely.
mimillerus likes this.
epd1210 is offline   Quote
Old 10-25-2019, 01:24 PM   #10
Jeeper
 
Join Date: Nov 2018
Posts: 30
Quote:
Originally Posted by epd1210 View Post
I hadn't thought of my power steering sensor. I have noticed the last 5000 miles, I am leaking power steering fluid. And it does rev up when idling sometimes too. Worth a look most definitely.

Check for this. Power steering fuid contaminating oxygen sensor.

Not sure if this forum supports links. You might need to copy / paste this into your browser.


https://www.dakota-durango.com/threa...sensor.116683/
mimillerus likes this.
smooth-rough is offline   Quote
Old 10-25-2019, 01:51 PM   #11
BM3
Jeeper
 
BM3's Avatar
 
Join Date: Jan 2016
Location: Cedar Rapids, Ia.
Posts: 255
Also what brand of O2 sensor was used... MY 98 only likes the NTK/NGK, and other brands only gave more issues....
mimillerus likes this.
BM3 is offline   Quote
Old 11-15-2019, 10:37 AM
Thread Starter
  #12
Newb
 
Join Date: Oct 2018
Location: Indiana
Posts: 9
ntk 23151 and 23099 sensors from Rock Auto.
Still giving me fits!
epd1210 is offline   Quote
Old 11-15-2019, 12:00 PM   #13
BM3
Jeeper
 
BM3's Avatar
 
Join Date: Jan 2016
Location: Cedar Rapids, Ia.
Posts: 255
IIRC another thing that could cause these issues is a Coolant temp sensor.... but research it to make sure... @jerryb ransford I believe posted about that once
BM3 is offline   Quote
Old 11-15-2019, 11:23 PM   #14
Jeeper
 
Join Date: Jan 2019
Location: Round Rock, TX
Posts: 433
Do you have a scan tool? You really need to plug one in and look at the O2 voltage in live data. Also short and long term fuel trim would be helpful. It may be as simple as the o2 signal wire is shorted to ground which the PCM could take it as a lean condition and start adding fuel.

We are kind of guessing otherwise.
mimillerus likes this.
sequel is offline   Quote
Old 11-16-2019, 12:41 PM   #15
Jeeper
 
Join Date: Sep 2019
Posts: 57
don't forget the basics. ground connections, bare, smashed wires, harnesses, fuses, bad splices, corrosion, fuses. that's what finally fixed my o2 sensor codes and rough erratic running problems. not sure which fixed it but something i did while performing the above finally fixed it.

mimillerus is offline   Quote
Reply

Tags
black soot , p0138 , p0171

Thread Tools

Posting Rules
You may not post new threads
You may not 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






All times are GMT -5. The time now is 11:10 AM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.1
User Alert System provided by Advanced User Tagging v3.1.0 (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.

Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, Gladiator, Mopar and Grand Cherokee are copyrighted and trademarked to FCA US LLC.
Wranglerforum.com is not in any way associated with FCA US LLC.