Jason_CPAPS
Full Access Members
Can I get rid of all 4 cats and not have a CEL?
get rid of cats?
- Thread starter Jason_CPAPS
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
tonydiv
technical advisor
How would you pass state inspection?
panda24619
Full Access Members
simple answer. no. you need the front two.
Jason_CPAPS
Full Access Members
ok thought so. for older vehicles its alot easier expecially when you know someone who does the inspections
Jason_CPAPS
Full Access Members
So replace the front cats and get rid of back. Is this where I use the spark plug non foulers? old rear cats will remain for visual. You guys have a recommended vendor to get the front cats from?
joecrotch
Full Access Members
i have no cats and non fouler's and get no CEL. Warning though my state does not do any kind of vehicle inspections, as long as you have insurance you can register a vehicle.
this is what I noticed after removing all 4 cats. The acceleration is much better, throttle response is incredible. I seem to use less of the gas pedal to achieve the same effect.
I still have the stock muffler so cruising is still mellow, when I hit the gas it gets a nice low rumble, sounds like a very expensive exhaust system.
Another plus was my gas does'nt seem to disapear as fast as it use to, I need to check what my actual mileage is.
this is what I noticed after removing all 4 cats. The acceleration is much better, throttle response is incredible. I seem to use less of the gas pedal to achieve the same effect.
I still have the stock muffler so cruising is still mellow, when I hit the gas it gets a nice low rumble, sounds like a very expensive exhaust system.
Another plus was my gas does'nt seem to disapear as fast as it use to, I need to check what my actual mileage is.
Jason_CPAPS
Full Access Members
are you just using non foulers on the rear o2s. All my cats are gutted because they were seriously stopped up. I am getting P0171 and P0174 banks 1 and 2 lean. I didn't get these codes til the cats were gutted. Emissions inspection up here depends on the county. Everyone doesn't have to have it
Thermo
technical advisor
- Joined
- Apr 18, 2011
- Posts
- 1,404
- Reaction score
- 65
jason, you can get rid of all of the cats, but then you have to install an O2 sensor simulator. The computer is looking for a difference between the upstream and downstream O2 levels. If it doesn't see this, it will cause the CEL to come on. This is how the computer monitors if the cat is functioning properly or not. As long as you keep the front cat (ie, the one between the upstream and downstream sensors), you are fine. You just need some sort of cat between the two to alter the O2 levels.
Jason_CPAPS
Full Access Members
Thermo do I need the simulator for all 4 o2s or just the rear 2?
The front o2's are used by the ecu for tuning purposes and are ahead of the cats. They will not be affected in anyway by removal of the cats. They are also very important for the ecu's ability to properly tune. Do not screw with the front 02's.
Jason_CPAPS
Full Access Members
ok so what I have going on now is that all cats are gutted front o2s haven't been touched. rear o2s have the spark plug non foulers and im getting the CEL for both banks lean. Based on what i've read and you guys are saying it is poosible that the codes arent from the cats being gutted?
FordandPolaris
Full Access Members
Have you checked the elbow leading into the back of intake? Could be causing a vacuum leak leading to the P0171 or P0174 codes.
http://www.expeditionforum.com/showthread.php?t=4926
This is what caused my "running lean" codes. However I still have all 4 cats stock.
http://www.expeditionforum.com/showthread.php?t=4926
This is what caused my "running lean" codes. However I still have all 4 cats stock.
Last edited:
Thermo
technical advisor
- Joined
- Apr 18, 2011
- Posts
- 1,404
- Reaction score
- 65
Jason, the simulators for the O2 sensors only modify the signals that the rear O2 sensors are sending to the computer. It by no means affects the front O2 sensors.
As for your lean codes, based on what you are seeing, that is normally caused by a leaking boot on the backside of the intake manifold from the PCV valve. So, find the PCV valve on the passenger side valve cover, follow the plastic tube to the back of the intake. Where the rubber boot is there, I bet you will find that boot is torn. Install a new boot and all is good. If that doesn't fix your problem, then I would recommend cleaning your Mass Air Flow sensor. I would start with the MAF sensor if you just recently cleaned/installed a K&N filter.
As for your lean codes, based on what you are seeing, that is normally caused by a leaking boot on the backside of the intake manifold from the PCV valve. So, find the PCV valve on the passenger side valve cover, follow the plastic tube to the back of the intake. Where the rubber boot is there, I bet you will find that boot is torn. Install a new boot and all is good. If that doesn't fix your problem, then I would recommend cleaning your Mass Air Flow sensor. I would start with the MAF sensor if you just recently cleaned/installed a K&N filter.
Jason_CPAPS
Full Access Members
Here is what i've done so far. Replaced cops and plugs, Diff feedback pressure sensor, gutted the cats, cleaned MAF, replaced pcv valve and boot at back of hose, just replaced fuel filter today, replaced air filter.. This truck was a mess when i bought it. Atleast it runs good now. The best I can tell with both banks lean its either exhaust leak, vac leak or intake gasket leaking. Just not sure where to start. The reason the cats are gutted is because they were completely melted. Never seen anything like it before. The front two were blown out in the front, almost looked like the cought on fire and blew up. What are the chances of the plastic tube running from the pvc to the boot has a crack in it that I cannot see?. Maybe i should just go to the blue oval and get the assembly boot and valve from them and see what that does.
Last edited:
joecrotch
Full Access Members
Sorry my internet was down today.
What i did was cut all four cats out and replaced with a straight pipe I had accidently cut out where the rear 02 sensors go so I welded in a bung and then on the rear only, 02 sensors I put the non foulers. because the foulers move the sensors out of the exhaust stream they do read a difference in 02 levels and no codes are thrown. I have used the emulators on a saab project and they work well. I just prefer the fowlers because they are cheap and do the same thing. but both work great.
Good Luck!
What i did was cut all four cats out and replaced with a straight pipe I had accidently cut out where the rear 02 sensors go so I welded in a bung and then on the rear only, 02 sensors I put the non foulers. because the foulers move the sensors out of the exhaust stream they do read a difference in 02 levels and no codes are thrown. I have used the emulators on a saab project and they work well. I just prefer the fowlers because they are cheap and do the same thing. but both work great.
Good Luck!
Last edited:
Idahokid
Full Access Members
I looked at a 1998 with a 4.6 with the rear cats removed,engine light was on and the idle was up and down at start up.The ilde would rise and drop a couple hundred rpm.Ran perfect otherwise.The owner told me to buy heated 02 sensors to turn the engine light off and the idle would smooth out.Any truth to that?It also has dual exhaust.Has a noisey flowmaster.One pipe in and two out.After running the expedition on the highway,it idled fine.
spadesluck
Well-Known Member
If you are serious in purchasing the vehicle I would take it to Auto Zone to see what the code is. If it is indeed the cat then non-foulers could be used for the rears sensors to try and get rid of them. However I do not think a rear sensor throwing a code messes with the idle at all.
The expedition comes with heated O2 sensors from the factory. Not sure how it would be possible to plug in incorrect non-heated units when one connector has 4 wires and the other 2?!
I would in no way trust what he says. If thats all that was necessary to get it running correctly why has he not done it? You can offer to buy it if he fixes it first with no cel or hunting idle..
As was said rear O2's have nothing to do with tuning and can not cause tune issues other than a cel. Front O2's are critical for the ecu to tune.
Last edited:
Just a thought I had based on my tuning.
When you remove all the cats the exhaust can run cooler. The front O2's need to be up to temp to read accurately. In the programming there is a table to adjust for duty cycle of the O2 heaters which I actually increased due to my 3" exhaust and larger shorty headers. The larger exhaust combined with less restriction allows the exhaust to cool much more before it exits.
So guess I am trying to say removing all your cats may throw your air fuel ratio off a bit. Wether its enough to cause any issue I really don't know.
When you remove all the cats the exhaust can run cooler. The front O2's need to be up to temp to read accurately. In the programming there is a table to adjust for duty cycle of the O2 heaters which I actually increased due to my 3" exhaust and larger shorty headers. The larger exhaust combined with less restriction allows the exhaust to cool much more before it exits.
So guess I am trying to say removing all your cats may throw your air fuel ratio off a bit. Wether its enough to cause any issue I really don't know.
Idahokid
Full Access Members
I thought it was a line of bull.I test drove it sunday.Monday morning he wanted to know what time I was stopping by to buy it.I told him dont call me I'll call you.I looked and drove another one today.Another 1998 with a 5.4 xlt.Original owner.Has 140,000 and its in showroom condition.$3500.00 bucks.I told him I'll take it.Ford did all the oil changes and tune ups.I will pick it up in a couple days.I will post some pics.
Similar threads
