cruiser54

The "crush" was put in there, disguised as if for clearance, when in fact it was there to slow down the exhaust flow so it would be hotter when it got to the converter. Therefore, the converter would start working sooner.
Straight from a Field Engineer at Jeep who worked on the emissions compliance of the 4.0.

XJRed96

agreed some back pressure is needed which is why it's not beneficial for people who cut the exhaust off after the front pipe or after the manifolds unless it's a drag racer thats running at WOT all the time.... the cat and muffler provide more than ample resistance along with the diameter and length of the exhaust. but that crush in there is not helping with scavenging if anything it's disturbing the pulses.

MonacaYankee

How about this. I didn't want it there and It was removed. The purpose it was there for is to heat the cat up faster which I read years ago from someone who was told by one of the emissions engineers. I don't understand why your so upset about it.
Technically all you need to run it is the header...which I have done before. All the torque is made in the header. The rest is just extra for emissions noise..etc

And if you read his post he was talking about the exhaust gasket leaking.

Firestorm500

By heating up the cat faster, the engine is able to come out of cold/rich mode quicker. That improves emissions, power, and fuel mileage.

By eliminating the crease, you have decreased performance of your Jeep and made the air we all breathe a little dirtier. Congratulations.

MonacaYankee

That's controlled by the coolant temp sensor FYI. Then the front o2 sensor is the only other thing exhaust related that alters fuel/air mix. Fellow jeep driver complaining about a jeep not being green enough lol. At least go get your Prius first then you can act like the Prius lady.

My average per tank went from 350 to almost 380 when I used to track it by month. I did the exhaust last year so it's paid for itself.

Firestorm500

So, you must have installed an auxiliary 50 gallon tank in your cargo compartment.

Actually, my normal daily driver is an ULEV V-6 Honda Accord EX. Not a hybrid.

cruiser54

Except on a Renix. It goes into closed loop within a minute or so as that system does not use the CTS to trigger closed loop.

sheepdog707

Have we figured out the vibes situation? Hahahaha I've got the same vibes at around 60+... There is a smidge of play on the ball joints so I'm assuming that's the issue.... Won't know till I replace em... It's a freakin Jeep, 55mph to save fuel anyhow...

sheepdog707

Forgot to mention: I've got a 93 Stock suspension with 30" BFG A/T's (balanced, hahaha)

NJ200XJ

i have a similar highway vibration.. i know my rear sway bar is broken, and the front sway bar bushings are shot..., does anyone think either of those two can cause a vibration?

bigvig

Those can definitely cause vibrations.

sheepdog707

Sway bars control body roll and do ZERO to dampen shock or vibration.... Shocks on the other hand could very well lead to vibrations. Ever see that car or truck on the highway with the wheel bouncing up and down? My vibes are coming from the front, seeing as my ball joints are worn, I'm guessing that's the issue... Kinda odd that 92/93 are always getting vibes...

TwoXJS

Hey guys. Sorry, I completely forgot about this thread....I posted a new one a few minutes ago about probably narrowing it down. Didn't get any emails about this one's replies....Sorry!

Firestorm500

Bushings and sway bars and ball joints don't rotate. You have to have something rotating to cause a vibration.

sheepdog707

Vibrations, shaking, shutters.... It doesn't matter, anything can cause it; it doesn't have to rotate. Death wobble feels like a vibration... How else would you describe it? Make sure you check things that are supposed to be tight and firm but aren't (ball joints, tie rods....) and make sure your shocks aren't blown.... A tire bouncing up and down the highway is annoying as hell and FEELS like a vibration in the chassis