O2 sensor issue

[djjcom]

So I posted a month ago about an 02 sensor issue (P0133) I've been having looking for help. I have not come any closer to fixing it.

2006, 4.0, 115km, Auto TJ

So far I have:
Fitted 4 NTK sensors
Bought a new PCM from wranglerfix
Had it smoke tested by a mechanic for exhaust leaks - no leaks except a small amount from throttle body
Had an auto electrician check the wiring - No issues.

Nothing has brought me closer to fixing the issue. I am getting roughly 250km (155 miles) per tank. This is about half of what it originally was. The idle is a bit rough too.
Originally I replaced the spark plugs to try and fix this issue and after doing so that's when both upstream 02 sensor codes came up (p0133 and p0153). After replacing the sensors the P0133 still continued to come back.
It also might be noting as well when I switched over the PCM and drove it around (roughly 50km) it looked like it was doing good on fuel until suddenly the gauge adjusted and it went down to show its used a lot more.

What should I do now?

Should I buy another sensor? Is it the spark plugs? Fuel issue? PCM?

Please, any additional help will be greatly appreciated. It's almost not worth driving at this point with how much fuel its using.

 

[macleanflood]

My 97 had terrible gas mileage when I had a cracked header.

I don't doubt you paid people to do work...but I'd suggest repeating all of it yourself. I don't trust any mechanics these days.

Run some Seafoam through the engine...start it up, pop the hood, one hand on the throttle linkage...pull the vacuum line off the brake booster and dip it in the can. Rev it up and modulate the cab keeping it running.

Also...what are your fuel trims, O2 sensor voltages? Can you read live ODB data? A Bluetooth dongle and the free app Torque Lite will do it.

-Mac

 

[Link]

As mentioned already, I’d be looking at live data. The numbers won’t mean anything at first but note the general range of both upstream sensors and either post the data here or google it.

 

[Bigfoot-NM]

Something I didn't see in your write-up......check your two precats. You will have to drop the exhaust to do it.

 

[macleanflood]

Something I didn't see in your write-up......check your two precats. You will have to drop the exhaust to do it.

IR gun before the cat, on and after?

-Mac

 

[Link]

Something I didn't see in your write-up......check your two precats. You will have to drop the exhaust to do it.

Good point. Worth checking at least.

He should be able to put a back pressure gauge in the upstream O2 sensor ports (one at a time) and measure to see if there are any upstream catalytic condenser restrictions.

I’m not vouching for the brand but here’s an example of the tool.

https://www.amazon.com/LUTIFIX-Pres...ent-Cat-Back/dp/B0BDFD13DX?tag=wranglerorg-20

 

[djjcom]

I'll do a drive tomorrow and record the data to post here.
The voltages looked normal when I was watching it and truthfully i'm not sure what the fuel trims are suppose to look like normally.

It might also be worth mentioning i also have the problem from SB 25-001-07 but I can't see that causing this issue.

 

[djjcom]

Good point. Worth checking at least.

He should be able to put a back pressure gauge in the upstream O2 sensor ports (one at a time) and measure to see if there are any upstream catalytic condenser restrictions.

I’m not vouching for the brand but here’s an example of the tool.

https://www.amazon.com/LUTIFIX-Pres...ent-Cat-Back/dp/B0BDFD13DX?tag=wranglerorg-20

The mechanic's I saw did not suspect it would be the cats as it should be obvious when driving and I feel the same way.

 

[JKP]

One partially clogged upper converter wouldn't be that obvious.

If they blow out and clog the 3rd converter, the Jeep will have no power.

 

[djjcom]

One partially clogged upper converter wouldn't be that obvious.

If they blow out and clog the 3rd converter, the Jeep will have no power.

View attachment 619837

Is there an easier way to check without taking out the entire cat and exhaust?

 

[JKP]

As stated above, use a backpressure gauge in the O2 bungs.

 

[djjcom]

As stated above, use a backpressure gauge in the O2 bungs.

When it was smoked tested I’m pretty sure he said he tested the cats but I’ll call and confirm.

If the cats come back fine, what else am I left with trying?

 

[macleanflood]

If the cats come back fine, what else am I left with trying?

Maybe fuel pressure, Injectors...heat soak as you mentioned.

-Mac

 

[JKP]

A smoke test is for leaks.

A backpressure test is for obstructions in the exh.

Completely different things.

 

[djjcom]

So I’ve bought a new sensor…. The code has still returned

I’ve also pressure tested the cat and the gauge didn’t move at all when idle or revved.

I’m seriously lost on what else to try next… please help me anyone

 

[macleanflood]

I'd get a can of Seafoam. Start the engine. Pull the vacuum line off the vacuum booster. Dip it in the can and run the throttle body. Watch where the smoke comes out of the exhaust.

-Mac

 

[djjcom]

I'd get a can of Seafoam. Start the engine. Pull the vacuum line off the vacuum booster. Dip it in the can and run the throttle body. Watch where the smoke comes out of the exhaust.

-Mac

Thanks Mac, had it smoke tested already by a trusted mechanic (5 star guy ). I could do it myself but I’m just hesitant to double up work I’ve done. Do you think spark plugs could cause this issue/code? When I put in the new ones these codes came up.

 

[JKP]

What plugs?

 

[hardtailpan]

I'll chime in here, what spark plugs did you use for replacements? I'm not sure exports use the same ones as US models, but use whatever the sticker on your hood tells you to use. Mine is some kind of NGK ZFR number, NGK ZFR5N I believe rockauto says. If you didn't use these, maybe start here. If you have the old ones, and they are in good shape, and they are these OEM NGKs, maybe clean em up and put em back in. I'm not saying this is your problem, but man, you got to find a baseline somewhere on this thing.

 

[djjcom]

What plugs?

spark plugs, NGK Zfr5n