2001 Ram 1500 5.9
New exhast system in the design stages needs your advice. I have a set of short headers that feed into the stock "Y" pipe. Just aft of the collection point is an O2 sensor than the cataylic converter (stock) than another O2 sensor. From the collection point of the stock "Y" pipe I will go 3 inch all the way back.

The pilot side of my brain says to cut the cataylic out, replace with a straight pipe and re-install the two O2 sensors. Then use a 3" OD Aero turbine muffler. Then straigt out the back.

The Engineer side of my brain says "HOLD ON". If mother mopar took the time and trouble to measure O2 before the cataylic converter and after. The trucks computer must be sensing some sort of differental through the cataylic and making adjustments some place.

I plan to install the cataylic when I have to have the truck tested every two years for emissions. Using 3 bolt flanges at each end.

Questions:

Is this a bad idea? Why?
Should I just install a race cataylic?
Can I run the truck with both O2 sensors discoinected? Will I die?

Thanks everyone

 

a CC really helps polution and smog.. so i wouldnt suggest doing that.. as a favor to the rest of us.. a highflow cat from magnaflow will give you plenty of air movement... these are direct fit and are sold at summitracing.. i have one on my 01 but it was advertised for a 94-99 .. i took the chance on it fitting my 01 and it did.. minor welding involoved but a clamp woudl work too.. as far as the 02.. i wouldnt delete those.. if you still delete the cat.. use a sim atleast.. the foward 02 measure for misture and will tell the pcm to ajust it accordingly. and after 02 measure cat efficicency... the aft one is the only one you would have to simm and these simms can be had allover the net.. you would just have to install the CC, bung, and 02 whenever you do your emisions testing.. here in NY we gotta do it every year and its a pain... its no fun having all them sick goodies on your truck when its not street legal and wont pass inspection!!!!


edit: ive "HEARD" that not running a cat can burn up your vavles.. i dont remembner where the hell i heard this and if this is true or not.. i dont think it is.. but its always scared me enought to not do it... you wont die if you dont run o2's but taht ANOYING CEL will stay on and will make it even harder to pass emisions/inspections if thats something they check for..

finall suggestion.. install a highflow magnaflow cat.. i think youll be happy.. i know i was!

 

Thanks for the info Shott. We wouldn't want to damage the gray owles and such. I hear ya though and agree.

I have never heard of these sims. What does it do? I'm leaning towards your advice for a high flow CC. I found a recal on the 2001 CC from Mopar as well. Interesting.

I think the "burning valves" is an old wise tail. Most aircraft run straight out the pipe. The trick (or therory) is get rid of the exhaust gases and heat ASAP. If anything. You would think a restrictive exhaust would burn valves by impeading the flow or restricting it. I understand two stroke tunning and pressure waves for scavenging and so on. I like the idea behind the Aero Turbine design. Decrease volictity, increas presure.

Air testing here in Ontario is recent in the past 3 years. It's quite a money maker fior shops and the government. In British Columbia, Canada they did away with public safety testing of your car each year. They would test usless things like....Um....BRAKES! lights, wipers look under the car, steering and alingment and general condion of the car. The government replaced all the test station with AIR-CARE inspection stations. This is a true story. I went through and failed on the first pass with a stock 318 1970 Dart. Drove around the block and went through a different lane and passed all within 5 min. I asked the supervisor what standards the units were calibrated too. He had no idea what I was talking about. It was $25.00 each trip through and I noticed many dead seagulls in the parking lot fro CO2 poisioning....LOL.

By the way. My CC is part of the "Y" pipe and it looks like she is orginal equip from Mopar. The truck has only 60k on her.

Bee Good!

 

I took the cat out of my '98 and then just re-installed the o2 sensors. No CEL yet. A buddy removed his in his '99 over a year ago and no CEL. We have no emmision testing here in Northern B.C.

You'll definitely have to put the pre-cat o2 back in as it is used by the pcm to adjust fuel/air mixture. I beleive the post-cat o2 is basically comparing the gases before and after to test whether or not your cat has gone bad. You can run a sim on the post-cat o2.

I've gotten away from using a sim for now but if the CEL comes on I'll be looking for one. I think I've seen sims on the fastman website when I was checking out their throttle bodies.

One other thing to consider is the cat does quiet the exhaust some. Without the cat and running 3" in/out muffler, my truck is a little on the loud side or at least the girlfriend thinks so. Everyone else says it sounds awesome.

Just a little warning that it does bring the decibel level up.

 

what i did on my 97 sport was, took a one inch piece of rebarb and pushed it throught the cat to punch it out. i still have the bung for the 02 sensor and with that little extra one inch hole it is a free flowing exhaust. you dont need to run with out cats they are illegal in some states. you might even get pulled over some time and they would inspect your truck right on the side of the road. no cats and they would tow it right there. plus a heafty fine.

 

http://www.o2simulator.com/24803.html

http://userwww.sfsu.edu/~ecg/o2sim.htm

http://www.bobblick.com/techref/proj...sim/o2sim.html

http://www.o2sensorsimulator.com/

just a few to get you started

 

http://www.thefastman.com/02Simms.asp

 

i have heard of a clogged cat damaging valves, but never no cat damaging valves. amanda does not have a cat, technically, because when hers went we didnt have the money to buy the huge pipe with the cat in it, and i dont weld...so we had it gutted. i dont if its louder, but it sounds different. sometimes gutting a cat will give you TOO much flow, and you will lose low end torque, but her truck pulled 2.06-2.09 60 foot times which i consider to be pretty good...

i thought that with the OBDII trucks you had to get an o2 simulator, because the computer would struggle with the post-cat O2 readings being so high, and constantly lean the truck out. that would cause increased combustion temperatures, and would eventually damage valves. but it has been said here that the post-cat o2 doesnt adjust things, so that may not be an issue,.

 

This is turning out to be very interesting and there is lots of great information out there. Turns out these sensors will degrade with age as well (makes sense (or)).... There is a spacific voltage that indicates to the computer perfect mixture of 14.7 to 1 (storch). I works kind of like an auto pilot where it has to go slightly off course to stay on course. So the out put voltage is always changing and the CPU is always adjusting. Different O2's and fuel injection system have different adjustment speeds or time. Direct port injection systems being the fasted to adjust per second. It's realy a change in the way we think about performance tuning. So the question is, Do I rebar the guts out? or do I check the operation of the cataylic & sensors. Seems that by going to a high performance cataylic a sensor simm is need or by deleting the cataylic a sensor simm is need. Sound is not my issue here as much as trying to fine tune what I have to work with. I'd like to run in the 12's but, not kill any gray owles with CO2.

 

Correct and correct.

Also correct I installed a race pipe on my '99 Grand Prix GT, and within the first few miles the SES light came on. I thought no big deal, won't hurt anything and I'll get the code programmed out someday. Well, turns out it will hurt the mileage, and the car ran extremely rich. The comptuer was seeing a lean condition because of the loss of the converter, and kept trying to richen things up before finally locking into limp mode. As soon as I installed a simm, that cleared up. The car still doesn't run right though, as I ran it rich long enough to damage my upstream sensor. Now I need to shell out $85 for a new upstream sensor [:'(]