96 explorer 5.0 o2 sensor delete

[Prks88]

Hi guys,
Do I got a rock crawler that I built from a explorer 5.0 1996.
I am in Montana where smog is no problem.
Question is this thing runs a little rough, when I built it I put headers on and both banks go into collector with 3” magma flow muffler (no more cats) I have upstream o2 sensors in tact but rears where removed because cats where pulled. Plugs are black, runs rich, is this because down stream sensors aren’t there? If I install them Into exhaust even without cats in will it help? Any ideas are appreciated. Thanks guys

Ps. I know it’s illegal in most states but not here in Montana. So please don’t harp on me just trying to get it running cleaner.

 

[donalds]

the rear O2 sensors are just for catalytic converter monitoring

 

[Prks88]

Ok, so they don’t have anything to do with the way it runs really? Of corse I got CEL on dash as numerous items have been pulled from this thing that I didn’t need.
I’ve cleaned maf sensor, plugs, wires, coils, ect. Just runs rich, if I punch throttle it stutters hard but if I roll the throttle on it does fine. Any ideas?

 

[410Fortune]

I have some ideas
What are the codes?
You cannot just remove emissions items from a 5.0 and computer and expect it to run normally
The codes will tell you where to look
If you drive it enough cycles you will get catalyst efficiency codes because the two downstream sensors are MIA
You wre going to need a tune if you want that 96 5.0 computer to be happy after removing things it needs

Just because you do not have emissions does not mean there is a right way to delete things and a wrong one, your PCM is expecting to see sensors and emissions stuff, without the feedback from them it can only guess on how to run properly

 

[Prks88]

the rear O2 sensors are just for catalytic converter monitoring

Right, I get that. I’m just curious if not having them makes this thing run rough or not? If I punch them into the pipes where the cats used to be will it help or not make any difference?

 

[donalds]

Like 410 said above it will run badly without a tune

 

[410Fortune]

it will help with any catalyst efficiency codes yes
It will not help with EGR or EVAP transmission or speed sensor codes, which will cause it to run like crapola

 

[Blown]

One sensor gone bad can cause issues. For example, the lack of coolant temp sensor will keep it in rich warm-up mode.

Cats are a good thing, but your rig is offroad only.....................It's easiest to take the entire engine harness and all the sensors to the new rig.

That said, You can likely get it to run well with a tuner in Open Loop. Closed Loop Fuel is where the computer uses all sensors to make the best mileage. , In closed loop, it is going to be funky without the inputs the computer needs to tune it itself. You can force it to go and stay in Open Loop. Open Loop is fuel based on what you command in a table. Timing can be set in a table. In both tables you set the timing and fuel for a given load, simple. You need a tune and to work with a tuner who can tell you the minimal sensors to run it in Open Loop.....................I don't know.

 

[Prks88]

Ok, figured out my problem.
I added the two downstream o2 sensors, did not run any better. Checked plugs still black and still running rich as crud. I checked fuel pressure, was very weak. So I replaced fuel regulator and filter with fingers crossed. Nothing acted the same. It would start fine, idled fine, had bad sputtering problem mid range, had good high rpm once you got it there. I then pulled fuel pump out, found that factory pinch clamp had really bit into rubber hose connecting pick up tube to fuel pump. Noticed small slice along edge of this clamp. I put fuel pump in a clear container with gas while still plugged into harness and cycled key. There it was, pump was blowing gas out of that slice therefore not much pressure to engine. Changed out hose and runs like it did a year ago, amazing. Crazy how long it takes to chase out a problem sometimes.
Thanks to everyone for help.

 

[410Fortune]

well done!

Fuel pressure test would point where to look