Well the 1991 Exploder has the front catalytic (is that how you really spell that..LOL) converter plugged.
I looked between the two converters and saw no O2 sensor, and after both also didnt see an O2 sensor either. This Exploder will be a trail only rig. So the question is...

1) Is it better to buy replacement converters or just remove both?

I'm leaning towards just removing both and installing a straight pipe in their place.

2) Would this do anything to the run ability of the Exploder, or throw a code in the ECM?

-TheCompound

P.S. I hope some of you get a chance for snow wheeling this weekend, if this big storm hits like they say it might!

remove the 2nd cat, beat out the frist one, unless you feel like fawking with the goofy set up infront of the frist cat. Should run much better, mine did.

remove the 2nd cat, beat out the frist one, unless you feel like fawking with the goofy set up infront of the frist cat. Should run much better, mine did.

Sounds like a pretty good plan to me... whats the weird set up with the first Cat?
-TheCompound

it has a 3 bolt flange with an oval piece of tubing coming off the Y pipe. it is difficult to adapt to a normal piece of tubing.

Ditch the cats and run straight pipe. :flipoff2:

Ditch the cats and run straight pipe. :flipoff2:

LOL...right... I think I'll just rock the stock muffler until it falls off....:flipoff2:
-TheCompound

it has a 3 bolt flange with an oval piece of tubing coming off the Y pipe. it is difficult to adapt to a normal piece of tubing.

yes and I was trying to find one at work for a customer and the aftermarket does not make them, ford discontinued them but even if they didn't they listed for $1800 some dollars, just knock the first cat out and weld a universal cat in behind it.

It will run MUCH better without the cat.

Idle rumble will sound pretty good too. :smokin:

i ran punched cats in my b2 and explorer, both ran great but if i let them idle really long (say 20-30 mins) it would toss a code at me but go away once i started moving. if its clogged just bunch them both out, no need for welding then because any local shop will have the 2 bolt flange for off the cats

i ran punched cats in my b2 and explorer, both ran great but if i let them idle really long (say 20-30 mins) it would toss a code at me but go away once i started moving. if its clogged just bunch them both out, no need for welding then because any local shop will have the 2 bolt flange for off the cats

Now that sounds weird... Did you ever figure out which code it was throwing?
-TheCompound

With the early OHV OBD 1 4.0 V6, there is no reason a code should pop up.

The only reason running without a cat will ever cause a code is when there are post-cat O2 sensors.

All OBD 1 rigs have O2s in front of the cats.

Although, I do not remember if the EGR was connected to the car housing or not on the 4.0

Was the code an EGR code?

if there is a 02 sensor behind the cat it will throw a light. If not, it will never know.

My 91 and 93 both had o2's in the Y pipe, pound em out. That and a flowmaster with a side exit sounds pretty good.

Now that sounds weird... Did you ever figure out which code it was throwing?
-TheCompound

i never pulled the code, i just assumed it was bad O2 reading due to drop in back pressure. the light only came on after punching the cat but as i said, it only happend when idle for a long period of time. this was with the 2.9L and the 4.0 OHV (both with O2's before the cat)

Exhust back pressure is read by the coumpter on most cars and trucks,so any change could make the motor run porley. A computer chip may be needed if you change the exhaust. O2 sensor on the norm. is in the exhaust manifold, v8 on the right.

Exhust back pressure is read by the coumpter on most cars and trucks,so any change could make the motor run porley. A computer chip may be needed if you change the exhaust. O2 sensor on the norm. is in the exhaust manifold, v8 on the right.

Now what reads exhaust back pressure??

I think even if both cats are punched out. By running muffler, there will be enough back pressure for the motor.
-TheCompound

:shaking:

it has nothing to do with back pressure. They are air/fuel readings. :shaking:

If there is an O2 sensor after a cat, its there to make sure that the cat is working correctly. If not, it will throw a "low cat efficiency" code. People and "backpressure" :shaking:


People need to learn before posting shit.

The post cat 02 checks to see if the cat is working properly and will throw a code if the cat is punched. If there is anything 'excessive' code wise with exhaust it would be EGR P0406, but that's neither her nor there with a cat.

Punched cats on OBDII systems should result in a P0420 code because the sensors will read too close to each other, hence low efficiency. P04XX (likely in the 20's) would be other possible outcomes). There are mil eliminators that allow you to ditch the secondary O2 sensors.

The post cat 02 checks to see if the cat is working properly and will throw a code if the cat is punched. If there is anything 'excessive' code wise with exhaust it would be EGR P0406, but that's neither her nor there with a cat.

Punched cats on OBDII systems should result in a P0420 code because the sensors will read too close to each other, hence low efficiency. P04XX (likely in the 20's) would be other possible outcomes). There are mil eliminators that allow you to ditch the secondary O2 sensors.

finally someone else who knows what they are talking about. :grinpimp:

Ive never used an eliminator, but lots of other people seem to have good results. :confused:

Exhust back pressure is read by the coumpter on most cars and trucks,so any change could make the motor run porley. A computer chip may be needed if you change the exhaust. O2 sensor on the norm. is in the exhaust manifold, v8 on the right.

Backpressure sensor eh?

:shaking:

The post cat 02 checks to see if the cat is working properly and will throw a code if the cat is punched. If there is anything 'excessive' code wise with exhaust it would be EGR P0406, but that's neither her nor there with a cat.

Punched cats on OBDII systems should result in a P0420 code because the sensors will read too close to each other, hence low efficiency. P04XX (likely in the 20's) would be other possible outcomes). There are mil eliminators that allow you to ditch the secondary O2 sensors.

THIS IS OBD 1

NO POST CAT O2 :flipoff2:

Might I add that running without a cat or with a gutted cat is actually illegal. Not enforced if you don't have emissions testing, but still illegal by federal law... Just saying.:flipoff2:

Might I add that running without a cat or with a gutted cat is actually illegal. Not enforced if you don't have emissions testing, but still illegal by federal law... Just saying.:flipoff2:

I understand that, but being just an trail rig I'm not too worried about it.
-TheCompound