Question about 1997 Jeep Wrangler

2 Answers

I have a 97 wrangler 2.5. Check engine light is on, running lean, loss of power and high fuel consumption. I have replaced the o2 sensors, reset check engine code. light stays off and engine runs great for a couple of days and then goes right back to running poorly / check engine light back on. I know its not the o2 sensors...what else could it be?

Posted by on

  • Mical Caterina
    Mical Caterina Mar 24, 2011

    What codes are you getting when you read OBII?

  • willoughby_c Mar 24, 2011

    When I replaced the o2 sensors and reset the code the fuel economy increased. Within a week the check engine light came back on and the fuel economy went back down. I had a diagnostic ran on it and was told that the upstream o2 sensor was detecting a lean mix. I blame the decreased fuel economy on over compensation on the acelerator to FORCE my jeep to run. I have also noticed a strong raw fuel smell from time to time.

×

2 Answers

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    Superstar:

    An expert that got 20 achievements.

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

  • Jeep Master
  • 6,982 Answers

Something odd about what you posted. An engine that is running lean shouldn't be using a lot of fuel. Lean is when there isn't enough fuel going into the engine. Two other sensors that regulate fuel flow are the map sensor and throttle position sensor. Temp sensor generally would cause a rich condition but I'd test that too. Be sure to check for vacuum leaks at the manifold and lines as well as fittings... A vacuum leak will give the O2 sensor a lean reading...seeing that, the computer will try to compensate by adding fuel. Clearing codes can change the way it's running but as soon as the computer runs through it's internal diagnostics it will turn the light back on if there is a problem.

Posted on Mar 24, 2011

  • 2 more comments 
  • willoughby_c Mar 24, 2011

    When I replaced the o2 sensors and reset the code the fuel economy increased. Within a week the check engine light came back on and the fuel economy went back down. I had a diagnostic ran on it and was told that the upstream o2 sensor was detecting a lean mix. I blame the decreased fuel economy on over compensation on the acelerator to FORCE my jeep to run. I have also noticed a strong raw fuel smell from time to time.

  • Richard Scordino Mar 24, 2011

    OK, O2 sensors are seeing a lean exhaust...as I mentioned, an intake gasket or any other vacuum leaks can do that. Also check where the exhaust runners join together. A crack there can pull in enough air to alter the mixture the sensor is seeing.

  • willoughby_c Mar 24, 2011

    There is a leak at the joint from the exhaust manifold to the pipe.

  • Richard Scordino Mar 24, 2011

    That little engine does not make very much power to begin with. (I've got four Cherokees...one has a four cyl and that's the one nobody wants to drive) If the exhaust leak is bad enough to get air into the system, the additional fuel called for can lead to problems with the converter. Even a slight restriction in the cat can result in much lower power. I'd have the pipe welded if possible or replace it but before condemning the cat, try driving it. Bad converters will often make a wheezing sound when you get on the gas.

×

  • Level 2:

    An expert who has achieved level 2 by getting 100 points

    MVP:

    An expert that got 5 achievements.

    Governor:

    An expert whose answer got voted for 20 times.

    Hot-Shot:

    An expert who has answered 20 questions.

  • Expert
  • 136 Answers

Do you remember the code? With the symptoms you are describing and I am assuming an O2 sensor code since you replaced them, It seems as if the catalytic converter may be bad. Do you hear any rattling type noises under the Jeep, especially when started cold or just when the engine is shut off?

Posted on Mar 24, 2011

  • 2 more comments 
  • willoughby_c Mar 24, 2011

    The engine is always noisy. It does rattle a lot and seems to have leaky exhaust. I have checked for vacuum leaks and found none. Just replaced the plugs, wires, rotor button, and dist cap along with the upstream o2 sensor.

  • TJ McDonald Mar 24, 2011

    The downstream (or second in line) O2 sensor takes a reading after the catalytic converter. It compares with the reading from the upstream sensor and will try to adjust the fuel curve to the engine to improve emissions. This would cause the lean condition reading for O2 sensor #1. The bad converter will cause the symptoms you describe.

  • willoughby_c Mar 24, 2011

    Could a leaky ekhaust cause the same issue? There is a leak at the connection from the manifold to the exhaust pipe before the converter.

  • TJ McDonald Mar 24, 2011

    Yes, it sure will.

×

1 Suggested Answer

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
goodluck!

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

Codes P2270& P2272 after oil change check engine light on drove under 100 miles both O2 sensors bad .Could shop have caused this somehow??? Maybe banging them or something ?


make sure they are plugged in tight Definition of Diagnostic Trouble Code P2270 Category: Powertrain Definition: O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 2Note: This definition of P2270 is applied to all manufacturers

P2270 - O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 2 Comments ' Add Yours
Possible causes
- Faulty Rear Heated Oxygen Sensor Bank 1
- Rear Heated Oxygen Sensor Bank 1 harness is open or shorted
- Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection
- Exhaust gas leaks Help with this
When is the code detected?
The Powertrain Control Module (PCM) detected the HO2S12 sensor has reported a lean condition for an extended period during an intrusive test
Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- High Fuel Consumption
- Excessive Smoke from Exhaust
P2270 Description
The Powertrain Control Module (PCM) supplies a voltage of about 450 mV between the HO2S high and low signal circuits. The oxygen sensor varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean.
The PCM monitors and stores the heated oxygen sensor (HO2S) voltage information. The PCMevaluates the HO2S voltage samples in order to determine the amount of time the HO2S voltage was out of range. The PCM compares the stored HO2S voltage samples taken within each sample period and determines if majority of the samples are out of the operating range.

Definition of Diagnostic Trouble Code P2272 Category: Powertrain Definition: O2 Sensor Signal Biased/Stuck Lean Bank 2 Sensor 2Note: This definition of P2272 is applied to all manufacturers

P2272 - O2 Sensor Signal Biased/Stuck Lean Bank 2 Sensor 2
' Add Comment
Possible causes
- Faulty Rear Heated Oxygen Sensor Bank 2
- Rear Heated Oxygen Sensor Bank 2 harness is open or shorted
- Rear Heated Oxygen Sensor Bank 2 circuit poor electrical connection
- Exhaust gas leaks
What does this mean?
When is the code detected?
The Powertrain Control Module (PCM) detected the HO2S22 sensor has reported a lean condition for an extended period during an intrusive test
Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- High Fuel Consumption
- Excessive Smoke from Exhaust
P2272 Description
The Powertrain Control Module (PCM) supplies a voltage of about 450 mV between the HO2S high and low signal circuits. The oxygen sensor varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean.
The PCM monitors and stores the heated oxygen sensor (HO2S) voltage information. The PCMevaluates the HO2S voltage samples in order to determine the amount of time the HO2S voltage was out of range. The PCM compares the stored HO2S voltage samples taken within each sample period and determines if majority of the samples are out of the operating range.
P2272 Information for specific makes
P2272 BMW
P2272 DODGE
P2272 FORD

Jul 30, 2015 | Cars & Trucks

1 Answer

The check engine comes on but I dont lose power the code it is showing is sid 152.does anyone know what it is.


some codes dont cause power loss or may not even notice anything wrong but a check engine light a p0152 code means following answer courtesy of OBD-CODES.com === P0152 O2 Sensor (High Voltage) OBD-II Trouble Code Technical Description Article by Dale Dale Toalston ASE Certified Technician 02 Sensor Circuit High Voltage (Bank 2 Sensor 1) What does that mean? The o2 (oxygen) sensors basically measure oxygen content in the exhaust. The PCM (powertrain control module) then uses this information to regulate fuel injector pulse. The o2 sensors are very important to proper operation of the engine. Problems with them can cause the PCM to add or take away too much fuel based on the faulty o2 sensor voltage. A P0152 code refers to the Bank 2, sensor 1, o2 sensor. (Bank 1 would contain cylinder 1 and bank 2 is the opposite bank. Bank 2 doesn't necessarily contain cylinder 2.) "Bank 2" refers to the side of the exhaust that DOES NOT contain cylinder number 1 and "Sensor 1" indicates that it is the pre-cat sensor, or forward(first) sensor on that bank. It is a four wire sensor. The PCM supplies a ground circuit and a reference voltage of about .5 volts on another circuit. Also for the o2 heater there is a battery voltage supply wire and another ground circuit for that. The o2 sensor heater allows the o2 sensor to warm up faster, thus achieving closed loop in less time than it would normally take for the exhaust to warm the sensor up to operating temperature. The O2 sensor varies the supplied reference voltage based on oxygen content in the exhaust. It is capable of varying from .1 to .9 volts, .1 indicating lean exhaust and .9 indicating rich exhaust. NOTE: A condensed explanation of fuel trims: If the o2 sensor indicates that the oxygen voltage reading is .9 volts or high, the PCM interprets this as a rich condition in the exhaust and as a result decreases the amount of fuel entering the engine by shortening injector "on time". The STFT (short term fuel trims) would reflect this change. The opposite would occur when the PCM sees a lean condition. The PCM would add fuel which would be indicated by a single digit positive STFT reading. On a normal engine the front o2 sensors switch rapidly back and forth two or three times per second and the STFT would shift positive and negative single digits to add and remove fuel to compensate at a similar rate. This little "dance" goes on to keep the air/fuel ratio at it's optimal level. Short term fuel trims or STFT reflect immediate changes in fuel injector "on-time" while long term fuel trims or LTFT reflect changes in fuel over a longer period of time. If your STFT or LTFT readings are in the positive double digits (ten or above), this indicates the fuel system has been adding an abnormal amount of fuel than is necessary to keep the proper air/fuel ratio. It may be overcompentsating for a vacuum leak or a stuck lean o2 sensor, etc. The opposite would be true if the fuel trim readings are in the negative double digits. It would indicate that the fuel system has been taking away excessive amounts of fuel, perhaps to compensate for leaking injectors or a stuck rich o2 sensor, etc. So when experiencing o2 related issues, reading your fuel trims can indicate what the PCM has been doing over the long term and short term with regard to fuel. This code indicates that the o2 sensor was stuck too high or in the rich position. The PCM monitors this voltage and if it determines that the voltage is too high out of range for too long, P0152 may set. Symptoms Symptoms may include: MIL (Malfunction Indicator Lamp) illumination Engine may run very rough Engine may be running lean or rich depending on if the o2 sensor is reading correctly or incorrectly Lack of power Increased fuel consumption Causes Potential causes of an P0152 code include: Bad bank 2, 1 o2 sensor incorrectly reading rich condition Engine running rich and o2 sensor Correctly reading rich condition Signal shorted to voltage in harness Wiring harness damage/melted due to contact with exhaust components Vacuum leak (make have lean codes (P0171, P0174) present with it) Leaking injectors Bad fuel pressure regulator Bad PCM Possible Solutions If you have any lean or rich codes associated with this code, focus on fixing these first because these can cause the o2 sensor voltage readings to appear to be faulty when they are in fact only reading correctly. So, with the engine running at operating temperature, use a scan tool to observe the Bank 2,1 o2 sensor voltage reading. Is it high? If so, look at the long term and short term fuel trim readings. The fuel trims are affected by the o2 sensors as noted above. If the LTFT reading for that bank is indicating negative double digits (PCM trying to take away fuel to compensate for problem) try inducing a vacuum leak to see if the sensor voltage then goes lean and the fuel trims increase. If the o2 sensor responds, suspect a problem with the engine, not the sensor. There may be other engine codes to help you. If the o2 sensor reading remains high (0.9 volts or above) and won't respond then shut off engine. With KOEO (Key on engine off) disconnect the o2 sensor and look for signs of corrosion or water intrustion. Repair as necessary. The voltage reading should now be about 0.5 volts. If so, replace the o2 sensor, it's shorted internally. If after unplugging the o2 sensor the voltage reading on the scan tool doesn't change, then suspect wiring problems. Inspect the harness and look for any melted wires or anywhere that the o2 sensor harness is making contact with the exhaust components. If you are unsure, you can check for continuity of all four wires between the sensor and the PCM with an ohmmeter. Any resistance at all indicates a problem. Repair as necessary.

Read more at: http://www.obd-codes.com/p0152
Copyright © OBD-Codes.com

Jul 28, 2015 | Cars & Trucks

3 Answers

2003 Nissan Altima 2.5L Service Engine Soon Light is on, Auto Zone says codes are for MAF and O2 Sensors. Car hard to start after driving a while but when starts appears to run smooth. Auto Zone thi


ok lets start with the codes they say your getting. P??? which 1's and how many. there are few o2 sensors, are they next to the Exhaust next to the converter? MASS AIR FLOW -MAF use this, for now i am guessing, until i see the correct codes your are getting. this could be the 1 you may have below, please read it........
  • P0103
    Mass Air Flow Sensor Circuit High Input
  • Possible causes
  • Faulty mass air flow sensor
    - Intake air leaks
    - Dirty mass air flow sensor
    - Dirty mass air filter
    - Mass air flow sensor harness is open or shorted
    - Mass air flow sensor circuit poor electrical connection
  • Before replacing the mass air flow sensor, try replacing the air filter and cleaning the air flow sensor with low compress air or mass air flow sensor cleaner. Reset code and drive vehicle. If the code comes back, it may be necessary to replaced the mass air flow sensor.
  • possible symptoms Engine Light ON (or Service Engine Soon Warning Light)
    - Engine stall
    - Engine running rough
    - Excessive fuel consumption
    - Excessive smoke
  • the code is generated when An excessively high voltage from the sensor is sent to Engine Control Module (ECM).
2003 NISSAN Altima Sedan OBDII Codes List

Oct 22, 2014 | 2003 Nissan Altima

1 Answer

I am getting 13 miles per gallon. what is wrong?


Your O2 sensor (or oxygen sensor) is located on your exhaust system. One placed before your coverter to measure the efficiency of the combustion in your engine by measuring the amount of oxygen left in the exhaust stream. The second O2 sensor is placed after the converter and its job is to measure the effiecency of the converter in filtering out harmful gases in the exhaust by compairing its reading to the sensor paced before the converter. If your O2 sensor has failed it will tell the car's computer that it is running too lean (more air than fuel) by default. Since the computer thinks the car is running lean, it now is adding more fuel to the mixture to try and compensate for the lean condition and will always have a check engine light on. If there is no check engine light on then it probably is not a faulty O2 sensor. Have a qualified technician run a fuel consumption test and go from there.

Apr 17, 2013 | 2002 Honda Odyssey

1 Answer

I have a 97 jeep wrangler 2.5 with auto trans. The last year I have replaced the up stream 02 sensor 7 times. The jeep will run fine for a month or so then the check engine light will come on. Its always...


My used 97 jeep wrangler fuel / economy problems: My vacuum canister was completely full with crud (replace). also my coolant temp sensor was bad (twice replaced), effects fuel mixture. and O2 sensors were bad (effect fuel mixture) due to being fouled by spraying too much oil on spector air filter (now wipe off excess and let dry in sun), also carb cleaner appeared to foul O2 sensors (stopped using). Also sensor input/output signals were constantly being interrupted by battery sliding into computer harness, which I cured by placing a 1" spacer on rear battery clamp to push battery away from computer. After curing these problems my fuel economy went from 55-60 miles per 1/4 tank to 75-80+ miles per 1/4 tank.

Nov 06, 2012 | 1997 Jeep Wrangler

2 Answers

P0138 and p0158


These codes, po 138 bank 1 sensor 2 shorted to voltage and code po158 means bank 2 sensor two shorted to voltage. these are the two rear oxygen sensors in the exhaust system. there two up frt and two in the rear, check the wiring on the two rear sensors, make sure that the wiring is not cut or stuck between metal. if the wiring is good then replace both rear sensors, when you get them ask for the left and right after the cat sensors. or bk1 s2 and bk2s2. after replacing them reset the computer. go to an auto parts sotre or if you have a code reader you can do it. hope this helps good day.

Feb 19, 2012 | 2004 Dodge Stratus

1 Answer

Check engine light was on. OBD II scan said both pre-Cat 02 sensors running lean. Also shows P0000 code which is a undefined code. S dash light comes every few days then transmission will stay stuck in 4th...


The pre cat sensors running lean does not mean they need to be replaced. They are are detecting a symptom. You need to know why.

If you are using a basic scantool (code only) you need to look up the P0000 code.
I thought this an odd code. I looked it up in my Autotap unit and it does not exist. The lowest # P (powertrain) code I have listed is P0016.

A regular scan tool, won't scan transmission or body codes, mu Auto tap doesn't either. You need a Tech 2 from the dealer for transmission codes.

First some history. The first O2 sensor was introduced in 1976 on a Volvo. California vehicles got them next in 1980, then federal emission laws made O2 sensors virtually mandatory on all cars and light trucks built since 1981. And now that OBD-II regulations are here (1996 and newer vehicles), most vehicles now have multiple O2 sensors, some as many as four!
The O2 sensor is mounted in the exhaust manifold to monitor how much unburned oxygen is in the exhaust. The signal from the O2 sensor tells the computer if the fuel mixture is burning rich (less oxygen) or lean (more oxygen).
A lot of factors affect the richness or leanness of the fuel mixture, including air temperature, engine coolant temperature, barometric pressure, throttle position, air flow and engine load. Other sensors monitor these factors too, but the O2 sensor is the master monitor for what's happening with the fuel mixture. Problems with the O2 sensor can throw the whole system out of whack.
The computer uses the oxygen sensor's input to fine tune the fuel mixture for the best balance of power, economy and emissions. The engineering term for this type of operation is "closed loop" because the computer is using the O2 sensor's input to adjust the fuel mixture. The result is a constant flip-flop back and forth from rich to lean which helps the catalytic converter operate at its best and keeps the average fuel mixture in proper balance to minimize emissions. It's a complicated setup but it works.
If no signal is received from the O2 sensor, like when a cold engine is first started (more on that in a minute) or the 02 sensor fails, the computer orders a steady, rich fuel mixture. This is referred to as "open loop" operation because no input is used from the O2 sensor to fine tune the fuel mixture. If the engine fails to go into closed loop when the O2 sensor reaches operating temperature, or drops out of closed loop because the O2 sensor's signal is lost, the engine will run too rich causing an increase in fuel consumption and emissions. As you might have guessed, that will set a code and turn on your check engine light.
How does it work? The O2 sensor produces a voltage once it gets hot. The sensor compares how much oxygen is in the exhaust to the oxygen in outside air. The greater the difference, the higher the voltage reading.
If you ever replace an O2 sensor (and if you're a DIY'er this is something you will do eventually), its important to remember that the O2 sensor needs to "breath" outside air to work. So don't put any grease on the sensor because it could block this air flow.
An oxygen sensor will typically generate up to about 0.9 volts when the fuel mixture is rich and there is little unburned oxygen left in the exhaust. When the mixture is lean, the sensor's output voltage will drop down to about 0.1 volts. When the air/fuel mixture is balanced or at the equilibrium point of about 14.7 to 1, the sensor will read around 0.45 volts.
When the computer reads a rich signal from the O2 sensor it leans the fuel mixture to reduce the sensor's reading. When the O2 sensor reading goes lean the computer reverses again making the fuel mixture go rich. This constant flip-flopping back and forth of the fuel mixture occurs anywhere from 2 to 7 times a second at 2500 rpm on OBDII vehicles, depending on what type of fuel injection system they have.
The oxygen sensor must be hot (about 600 degrees or higher) before it will start to generate a voltage signal. Many oxygen sensors have a small heating element inside to help them reach operating temperature more quickly.
Ok – that was a lot of info on what they do and how they work. The next thing to know is that trouble codes relating to O2 sensors are very common. But you really need investigate further before replacing an O2 sensor just because you got that trouble code. Armed with the information above on how often the O2 sensor "flips" back and forth and AutoTap or another scantool that allows you to monitor O2 sensor voltage, you can be certain whether the O2 sensor itself is really the problem. These sensors can be pricey, so don't just replace them the first time you see that trouble code!

The O2 sensors are expensive, diagnose what really is going on.

Jul 27, 2009 | 1999 Cadillac Catera

1 Answer

Check engine light codes and troubleshooting


Sounds like you have a vacuum leak for the lean code and the misfires. I don't see a 473 code in my manual, but have a 463. The 463 is for the fuel level sensor open or voltage high.

Jun 01, 2009 | 1998 Jeep Wrangler

1 Answer

97 jeep wrangler 2.5 running lean


check fuel pressure and check exhaust for leaks. exhaust leaks caqn play with the o2 sensor readings

Sep 15, 2008 | 1997 Jeep Wrangler

1 Answer

92 Jeep Wrangler MAP sensor bad?


This may not be your MAP but your Catlettic Converter. I also own a 92 Wrangler and had some of the same issues. My issue was actually a couple of things but they all came from a crack in my exhaust headder.

You may want to check your exhaust headder for cracks. If there is even a small one, (which are VERY common w/ YJ's) than your O2 sensor is thinking that the engine is running too lean. Therefor telling the fuel pump and injectors to dump more fuel into the engine. Well, truth is your not running too lean, in fact, you begin running too ritch.

The unburned fuel that is now comming out through your exhaust collects on the porslen screen inside your catalettic converter where it burns off, causing the screen to melt together. Resulting in a clogged cat.

The only way to fix this is to replace the ehaust headder (welding the crack will not work) and replacing the cat. This would explane your loss in gas mileage and power, due to over back pressure. The ticking sounds like the back pressure working on your valves.

Hopefully I'm wrong and this is not your issue because it is a very expencive repare. You're looking at around 350.00 to 500.00 just for a good headder and atleast 250.00 for the cat. However, an easy way to test this is to take a flash light and have a good look at your headder anywhere there are joints where pipes come together. Look for black, ashy spots above and around the joint. If you see this anywhere then I hate to tell you but this mite just be your problem.

Jul 26, 2008 | 1992 Jeep Wrangler

Not finding what you are looking for?
1997 Jeep Wrangler Logo

1,304 people viewed this question

Ask a Question

Usually answered in minutes!

Top Jeep Experts

yadayada
yadayada

Level 3 Expert

75797 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22114 Answers

Jeff Turcotte
Jeff Turcotte

Level 3 Expert

8152 Answers

Are you a Jeep Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...