4.0 on 33's struggles to go past 60 mph

Moglocker said:
I have the 32rh and 4.56 with 35s,I just got back from Denver with it barypulling itself ,got it home and still won’t go over 3000 rpm ,checking cats and will get back to the thread
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One thing I should've mentioned is that 95% of my driving is within a few hundred feet of sea level. I did a trip last weekend to some friends, and going over the mountains at 5k feet and driving around town at 3k feet there was a noticeable drop in power from my normal location. Idk if that would still apply if I was always driving around at higher elevations and the computer had time to adjust for it, but for a one weekend trip there was definitely a difference
 
Moglocker said:
How did you stop the Cel light after gutting the cats?
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Haven't gotten around to it yet, but I'll be buying credits for HPtuners and using my buddies setup to turn off the downstream O2 sensor codes permanently
 
Sensei said:
Holy shit this makes me want to go cut my cats off right now lol. I have a compression tester tool for my engine, so I just need to build that dummy o2 sensor you suggested and see what my readings are. Will report back. Thanks!
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Sounds good, I was never able to find the factory spec for back pressure for the jeep, and it's different for every vehicle, but I'd say 5psi or less is good, 5-10 psi at 3k+ rpm is questionable and anything more is bad.

Also, don't cut them off, just pull it and beat the material out and reinstall.

If you find bad back pressure at the upstream location, test the downstream location and see if it is the same. If so, it may just be your third cat that's plugged and you might be able to retain the upstream cats for a while longer
 
Trevlaw said:
Sounds good, I was never able to find the factory spec for back pressure for the jeep, and it's different for every vehicle, but I'd say 5psi or less is good, 5-10 psi at 3k+ rpm is questionable and anything more is bad.

Also, don't cut them off, just pull it and beat the material out and reinstall.

If you find bad back pressure at the upstream location, test the downstream location and see if it is the same. If so, it may just be your third cat that's plugged and you might be able to retain the upstream cats for a while longer
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My 3rd cat was unmonitored and I took it off when I did my t-t
 
Trevlaw said:
One thing I should've mentioned is that 95% of my driving is within a few hundred feet of sea level. I did a trip last weekend to some friends, and going over the mountains at 5k feet and driving around town at 3k feet there was a noticeable drop in power from my normal location. Idk if that would still apply if I was always driving around at higher elevations and the computer had time to adjust for it, but for a one weekend trip there was definitely a difference
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Yes but you could still drive it right?I was at 9000 and wouldn’t hardly pull itself,I think the washboarded road shook the cat apart
 
Moglocker said:
Yes but you could still drive it right?I was at 9000 and wouldn’t hardly pull itself,I think the washboarded road shook the cat apart
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Yeah, flat ground was fine, just a tad sluggish. The hills going up over the summit I was giving it quite a bit of gas just to maintain speed, where that same hill at a lower elevation I could accelerate from 65-80 going up it no problem
 
Trevlaw said:
Sounds good, I was never able to find the factory spec for back pressure for the jeep, and it's different for every vehicle, but I'd say 5psi or less is good, 5-10 psi at 3k+ rpm is questionable and anything more is bad.

Also, don't cut them off, just pull it and beat the material out and reinstall.

If you find bad back pressure at the upstream location, test the downstream location and see if it is the same. If so, it may just be your third cat that's plugged and you might be able to retain the upstream cats for a while longer
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Couldn't seem to read any psi at all. There was obvious backpressure though because the tone of the exhaust changed dramatically without any o2 plugged in, and I can feel the obvious backpressure with my hand. Yet with tool connected, can't get a reading. Tested my tool on a air compressor hose gun and was able to pull readings fine. So maybe my cat isnt clogged? I ordered this tool https://www.amazon.com/dp/B09CCWDKR6/?tag=wranglerorg-20 from amazon to test with again hopefully tuesday, I think the gauge is more sensitive.

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Sensei said:
Couldn't seem to read any psi at all. There was obvious backpressure though because the tone of the exhaust changed dramatically without any o2 plugged in, and I can feel the obvious backpressure with my hand. Yet with tool connected, can't get a reading. Tested my tool on a air compressor hose gun and was able to pull readings fine. So maybe my cat isnt clogged? I ordered this tool https://www.amazon.com/dp/B09CCWDKR6/?tag=wranglerorg-20 from amazon to test with again hopefully tuesday, I think the gauge is more sensitive.

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Where did you plug your test rig into? It looks like I can see the bottom of your trans oil pan in the first pic. You want to plug it into the upstream O2 sensor location right by the exhaust manifold. Ideally both upstream locations in case just one of the two mini cats is plugged
 
Sensei said:
Couldn't seem to read any psi at all. There was obvious backpressure though because the tone of the exhaust changed dramatically without any o2 plugged in, and I can feel the obvious backpressure with my hand. Yet with tool connected, can't get a reading. Tested my tool on a air compressor hose gun and was able to pull readings fine. So maybe my cat isnt clogged? I ordered this tool https://www.amazon.com/dp/B09CCWDKR6/?tag=wranglerorg-20 from amazon to test with again hopefully tuesday, I think the gauge is more sensitive.

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Trevlaw said:
Where did you plug your test rig into? It looks like I can see the bottom of your trans oil pan in the first pic. You want to plug it into the upstream O2 sensor location right by the exhaust manifold. Ideally both upstream locations in case just one of the two mini cats is plugged
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Yeah I plugged it into the o2 sensor by the trans, right before the cat. I didn't realize there were other o2 sensors. I'll do a bit of research, test it out, and report back. Thanks.
 
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Yeah I agree but unfortunately it's all I have on hand till Tuesday. I think you can use to check engine compression as well so that's why I figured it might work. But i'll try with the specialized tool again when it comes in this week. I'll also actually test the correct o2 port lol
 
Trevlaw said:
Where did you plug your test rig into? It looks like I can see the bottom of your trans oil pan in the first pic. You want to plug it into the upstream O2 sensor location right by the exhaust manifold. Ideally both upstream locations in case just one of the two mini cats is plugged
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I need to hook my test rig into Bank 1 Sensor 1 location? Right after the exhaust manifold? Hope the o2 sensor is the same thread size...
 
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Sensei said:
I need to hook my test rig into Bank 1 Sensor 1 location? Right after the exhaust manifold? I think I see it, going to test now.. Hope the o2 sensor is the same thread size...
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Yeah, if the cats are plugged and you test downstream of them it would make sense that there might not be back pressure.

You should see two small catalytic converters built into the downpipe that bolts to the manifold. Each has an O2 sensor before and after it, you want to test the upstream locations before the cats
 
Sensei said:
Yeah I plugged it into the o2 sensor by the trans, right before the cat. I didn't realize there were other o2 sensors. I'll do a bit of research, test it out, and report back. Thanks.
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I'm not sure why you have an O2 sensor that far downstream. Pretty sure your model year should only have the 4 of them around the mini cats up front. Sounds like a previous owner may have done some exhaust work
 
Trevlaw said:
I'm not sure why you have an O2 sensor that far downstream. Pretty sure your model year should only have the 4 of them around the mini cats up front. Sounds like a previous owner may have done some exhaust work
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I'll try and get a recording of my exhaust system and upload it here real quick. The only part I was aware that wasn't stock exhaust wise was the flowmaster muffler. Everything else I would thing is original. Will report back.
 
Trevlaw said:
I'm not sure why you have an O2 sensor that far downstream. Pretty sure your model year should only have the 4 of them around the mini cats up front. Sounds like a previous owner may have done some exhaust work
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Alright heres my exhaust..
 

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