97 SE Oxygen Sensor issues

Seems like I bought a lemon this year.
1997 Wrangler SE
Manual
131000 miles
4 Cyl 2.5 L :disappoin


I've been having Oxygen Sensor issues the whole time.

When the 'Check Engine' light isn't on i'm getting 15-17MPG, But once it comes on it's sucked to 9MPG if i'm lucky.:shakehead The OBD-II scanner reads "P-0171 - Fuel System Too Lean (Bank 1)"

Now what seems wrong here... Too lean means too much Oxygen, but it's sucking 2.5X too much gas.runaround I've sent it to techs but all they tell me is that the O2 sensor has went bad. :screwy: The only reason I feel that it's not a vacuum leak is it takes about 1,000 miles for the engine light to come back on and tick me off even more. This last time when I took the Sensor in to Autozone sales rep he said that it shouldn't look like it did... The tip was just chared, he said that i may have an injector stuck open, but if so why would it take so long for the computer to give an error and not just tell me an injector is bad?
REPLACED IT 14 TIMES THEY DON'T GO BAD LIKE THIS!!!

Work done to it has been pocket emptying. (JEEP. Just Empty Every Pocket)

1. NEW PCM
2. NEW Cat.
3. NEW muffler
4. 14 NEW O2 sensors
5. NEW Fuel pump.
6. NEW Iginition coil
7. NEW Crankshaft position sensor
8. Brake Line
add it all up it's taken a wopping $2300ish since January this year:banghead: (Autozone is loving me) Please if you have any thoughts:2cents: i'd love to hear them. :popcorn:

isn't the #1 cause of po 171 a vacuum leak? it is not a lemon just because people can't diagnos it right! get your self to an independant garage that is ase certified and in business for over 20 years. mike

I had a friend who replaced his downstream O2 sensor several times before replacing the upstream one, also...this fixed the problem. This may not be it, but there is a shop out there who will fix your rig without bleeding you dry.

JD
07 Sahara

Sorry, forgot to mention that i've relpaced the rear one 3 times (just to see if it'd work)...

If this helps anyone, i've noticed this within the past week, when just running down the interstates and backroads (delivery driver for pizza) it seems to do just fine.
But when I stop at a customers house or at a light, pretty much whenever it's at an idle, is when the profound smell of unburnt gas is overwhelming. And when the OBD-II scanner reads the codes, this is when 75% of the time it's actually pulling this stupid "fuel system too lean" crap

if you got a vacuum guage, see if you are getting vacuum to the fuel pressure regulator. if the regulator is not getting vacuum the regulator will not regulate hence the rich/lean fuel condition. you also will need to hook a fuel pressure guage up to it also.

Well, I caved and took to a different mechanic... He found cracks in the exhaust manifold... Got about 12hrs b4 I decide wether to go ahead and relpace the whole thing or just have it welded shut.

Any suggestions? and would a cracked manafold be legit. for what i've describes what's going wrong?

you can get a new one from ebay for under 75.00!!!! Im right now having same issues

Well, the exaust manifold didn't change a thing. If anything things go bad quicker now. I've bought another vehicle but i'm refusing to give up yet...

How can I tell if someone before me owning this Jeep did an engine swap? I asked one mechanic that it's been to why there were wires hanging around and he told me that they were for a 6cyl. Not thinking about it we went on.

Does 4cyls come with the wires for a 6cyl normally? A friend thinks that if an engine swap was done and the intake wasn't replaced (not being a mechanic i think it's all built together) that it's now pulling in enough air for a 6cyl which would be too much for a 4cyl thus causing a rich mixture and frying the sensors...

Well, I caved and took to a different mechanic... He found cracks in the exhaust manifold... Got about 12hrs b4 I decide wether to go ahead and relpace the whole thing or just have it welded shut.

Any suggestions? and would a cracked manafold be legit. for what i've describes what's going wrong?
what does this guy say about his missed diagnosis (get your money back)? is he ase certified? did he do the work or did you do the work?

Well, the exaust manifold didn't change a thing. If anything things go bad quicker now. I've bought another vehicle but i'm refusing to give up yet...

How can I tell if someone before me owning this Jeep did an engine swap? I asked one mechanic that it's been to why there were wires hanging around and he told me that they were for a 6cyl. Not thinking about it we went on.

Does 4cyls come with the wires for a 6cyl normally? A friend thinks that if an engine swap was done and the intake wasn't replaced (not being a mechanic i think it's all built together) that it's now pulling in enough air for a 6cyl which would be too much for a 4cyl thus causing a rich mixture and frying the sensors...
f you took it to a mechanic take it back to him for re-diagnosis and repair.

Exhaust manifolds cracking on Jeeps is common because the heat dissipation is not equal. Welding it will not help as it will crack again, replace it. What was the OBD code after replacing the manifold??

I was wondering about this 4 cylinder - 6cylinder thing that you are talking about. Now are there six fuel injector wires or are there just extra wires like around the firewall? There could be extra wires for things not installed on you Jeep. Can you provide a picture?

If someone swapped out the engine and installed a 4 cylinder instead you would have extra wires but the wiring harness are not the same nor is the computer system - NON COMPATIBLE.. so very unlikely.

You might try adding Seafoam to your gas tank to try and clean the fuel system and injectors.

He didn't do the work. My uncle has a mechanic friend and does work at his house for like 1/2 the labor price as long as I buy the parts. So I really can't take it back and complain to much.

Here's a link to pictures of the engine and random wires that someone told me that they go to a 6cyl. Couldn't find extra injector wires just hanging around.

http://s59.photobucket.com/albums/g282/darkangel32987/jeep/

The code that keeps coming up... and it's been the same all along... "P0171 Fuel system too lean bank 1" there was another at one point about the O2 sensor. But I don't remember which it was. I've read up there ^^^ that it could be a vacuum leak. If so... is there any hope with that or how would I go about trying to find it.

VAC LEak!! find it!!! These other so called mechanics wouldn't know their cranks from cams if it was written on them!!! Look over all you vac lines and with the engine running spray some carb cleaner around the intake gaskets to block. Are there any bolts missing? Once you spray listen for a change in the engine speed. PO171 IS a VAC LEAK, Get the valve cover filter off and get things hooked up as they should be also. THe fuel smell is the computer trying to compensate for the lean condition by dumping fuel, hence the poor milage.

Alright, finally got the nerve to work on this thing... found 2 vacuum leaks. Fixed them. Drove around and the dredded check engine light came back on. I've replaced the fuel pump, what about the fuel pressure regulator?