riskywhiskey

had a p0420 pop up i cleared it and put catyclear in the tank today because the cat system is 430$ for oem was wondering if this doesnt work....probably wont can you delete the factory dual cats and replace it with an aftermarket magnaflow single cat where the resonator is? or would that cause more with the O-2-the crappy gas mileage sensors

dave1123

That's not a resonator. It's an un-monitored cat and has a matrix in it. I thought mine was rattling so we cut it off and it's not baffled, but has a catalytic matrix in it so we welded it back on. One of the muffler baffles was rattling.

I'll bet you have a CA system, don't ya? NY requires all new cars after 99 to be CA compliant. Dual cats and 4 02s, right? Federal is 2 cats, 2 02s, and only 1 downstream 02. The Federal system requires PCM re-programming if switching from CA system. Also the CA system requires specific 02 sensors that are more expensive than the Federal ones.

riskywhiskey

3 I have 1 upstream 2 downstream right before the little cats I was going to put the magnaflos on but they won't fit in that location

dave1123

I sounds like you've got the Federal system then. My CA system has 2 little cats right under the brake booster with an 02 before and after each one, then the big can before the muffler. I put a shorter muffler from a 97 ZJ on it and it makes to sound a little better. At least I can hear how the engine is running now. I may replace this rattling thing with a Flowmaster, but I've got to keep in sound level down because I deliver newspapers late at night.

riskywhiskey

Nah I just got to looking I have the ca version 2 top 2 bottom so I'm basically stuck with oem replacement but I did find stainless on summit from magnaflow for 437$ so I may go with that and tube manifolds and a port polish , having a 6* advance flash done should net me roughly 27-28 highway with the 235s I'm getting 24-26 now with a ram air and #24 quadport injectors and it's snappy as hell even with tires at 31.7 inches high

riskywhiskey

And I have a thrush welded it's the same thing as a flow Master 40 but less cost has a nice deep growl can't say rumble 4.0 doesn't rumble it growls

riskywhiskey

ok so i did not see it was against forum rules to discuss this until recently i apologize..... i will be doing an oem replacement when and if needed not deleting the cats

00t444e

It isn't against the rules to talk about catalytic converters anymore, so you are good. Also 24-26 mpg is hard to believe, is that hand calculated or going off of the lie-o meter?

riskywhiskey

It was before the 235/85s spent 75$ at 2.75 a gallon down to NC and back which was 785 miles it equals 26.58 mpg all highway this was with adjusted tv cable #24 injectors and 6* timing advanced I will probably get about 23.3 or so with the lift and larger tires it may increase a hair or stay the same due to lower rpm I get now (was running 1950rpms factory tires now at 1650ish with larger tires )

riskywhiskey

You would honestly be surprised what you can get with a pcm recalibration which I have to have again since the larger tires due to speedo difference

dave1123

Just for information, in 2016 I made a trip from Syracuse NY to Rochester NY on the Thruway at 90+*F, round trip 195 miles including about 20 miles on surface streets before the return. I took a friend to pick up a truck he had bought, had lunch, then returned.

The road was basically flat, air temp was 95* with light wind from the west, no A/C with all 4 windows down, 245/70R16 tires, 3.55 gearing, 3 souls on board going out, 1 returning, running a constant 70 mph. The road was thru the Montezuma National Wildlife Refuge so the air was humid. Jeep had 195K miles on it with a new head. No other mods. It was recalled for a PCM reflash, intake manifold heat shield, and seat belt shoulder bolts.

Actual fuel mileage calculated by odometer reading and actual fuel usage was 27.42 which shocked me! The VIC said 26.2. I normally get 16.2 around town in the summer and 12 in the winter, less when doing my paper route. This is the only road trip I've ever made with this vehicle so far. OH... and I used the same gas station for both fill-ups.

riskywhiskey

Yeah the EPA estimated is wrong 18 town and 22 highway for the 4.0 I run 3:55s as well I may have to go 373s not sure yet

dave1123

One thing I do that may sound strange is on those lonely, dark, hilly country roads at night I lock out O/D. That way I get quicker throttle response and speed control at about 40-45 and it gives me time to react to deer-in-the-headlights!

riskywhiskey

I typically cruise at 40 highway I do 60 unless stated 55 so I'm not well liked in NC where it's 75mph cause I will do like 64-67

dave1123

Yeah, on the interstate I set my cruise at 68 and let people pass me if they like. I had my speedo checked by police stationary radar in the towns of Dewitt and Manlius and it reads 2-3 mph faster than the radar at various speeds. That's with 29.5" diameter tires.

I'm thinking of installing a Flowmaster 50. I want to hear how my engine is running but don't want to wake up my newspaper customers. What do you think? You're right about the sound a 6 makes. It's not the nice rumble of a V8.