Question for the 4.0'ers
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Junior Member
Joined: Apr 2013
Posts: 87
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From: Port St. John, Florida
Year: 1995
Model: Grand Cherokee
Engine: 4.0L I6 Power Tech Engine
Well, I've been dreading this for a while now, And I think the time has come. Ever since I got my 95 4.0 ZJ it's had a bad cat, Rattles really bad all the time, even at idle. So I gotta take it out, My muffler isn't too bad (For stock still) just some rust on the bottom.
So my question is, What kinda set ups do you guys have and what would you recommend? I live in Florida so I don't need to pass any emission tests or anything, so I'm not too worried about the Cat.
So my question is, What kinda set ups do you guys have and what would you recommend? I live in Florida so I don't need to pass any emission tests or anything, so I'm not too worried about the Cat.
Old fart with a wrench
Joined: Nov 2010
Posts: 14,398
Likes: 740
From: Manlius, east of Syracuse, NY
Year: 2000 XJ Sport & WJ Laredo
Model: Grand Cherokee (WJ)
Engine: 4.0L
You don't even have DMV inspections in Florida, do you?
I had a Chevy truck with a 350 and dual exhaust. I used cats for a 4 liter Chevy S10 pickup from NAPA and they were cheap. They are 2 1/2" in and out. If it were mine, I'd use that cat and a Flowmaster muffler. You'll have to add a section to connect to the standard tailpipe. The cat is tiny and only about 12" long. You'll have to weld a metric nut to the pipe to run the downstream 02 sensor, but it'll work. You might not even need the 02 sensor.
Also, add a muffler hanger to the system where the floorpan kicks up behind the rear seat. It helps stabilize the system and helps to prevent leaks.
I had a Chevy truck with a 350 and dual exhaust. I used cats for a 4 liter Chevy S10 pickup from NAPA and they were cheap. They are 2 1/2" in and out. If it were mine, I'd use that cat and a Flowmaster muffler. You'll have to add a section to connect to the standard tailpipe. The cat is tiny and only about 12" long. You'll have to weld a metric nut to the pipe to run the downstream 02 sensor, but it'll work. You might not even need the 02 sensor.
Also, add a muffler hanger to the system where the floorpan kicks up behind the rear seat. It helps stabilize the system and helps to prevent leaks.
Last edited by dave1123; Jul 24, 2014 at 10:13 AM.
Thread Starter
Junior Member
Joined: Apr 2013
Posts: 87
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From: Port St. John, Florida
Year: 1995
Model: Grand Cherokee
Engine: 4.0L I6 Power Tech Engine
Right on, Thanks for the reply Dave, Yeah I don't have to pass any inspections or anything (Thank god).
Everyone that I know around here no mater what kind of truck/car/suv they just cut the Cat out and put like a flowmaster 44 on it and thats it, I was thinking about doing the same, But not really sure on how that will sound. I don't want to do something, then have it sound like crap.
Everyone that I know around here no mater what kind of truck/car/suv they just cut the Cat out and put like a flowmaster 44 on it and thats it, I was thinking about doing the same, But not really sure on how that will sound. I don't want to do something, then have it sound like crap.
Old fart with a wrench
Joined: Nov 2010
Posts: 14,398
Likes: 740
From: Manlius, east of Syracuse, NY
Year: 2000 XJ Sport & WJ Laredo
Model: Grand Cherokee (WJ)
Engine: 4.0L
First of all, without the cat, the PCM might get confused and give you the wrong mixtures and error messages. It's also illegal Federally. IDK how you'd get caught out of state on this, but it's possible.
Second, a 6 doesn't sound like a V8, so don't expect it to. Personally I can't stand the sound of a 4 cylinder with a razzy muffler. I just grates on my nerves. In my opinion, the Flowmaster gives you the best sound you're going to get from the 6 because it mellows out the sound as much as possible and is built solidly. The cat will also smooth out the exhaust pulses. I have to warn you though, that little cat will change color from the heat.
My boss maintains a residence in Florida and has all his personal vehicles registered there, but he has his mechanic do the NY DMV inspection just to make sure he doesn't have a problem. I've driven his Toyota Rav4 and it doesn't have a NY inspection sticker on it. IDK how that works.
Second, a 6 doesn't sound like a V8, so don't expect it to. Personally I can't stand the sound of a 4 cylinder with a razzy muffler. I just grates on my nerves. In my opinion, the Flowmaster gives you the best sound you're going to get from the 6 because it mellows out the sound as much as possible and is built solidly. The cat will also smooth out the exhaust pulses. I have to warn you though, that little cat will change color from the heat.
My boss maintains a residence in Florida and has all his personal vehicles registered there, but he has his mechanic do the NY DMV inspection just to make sure he doesn't have a problem. I've driven his Toyota Rav4 and it doesn't have a NY inspection sticker on it. IDK how that works.
CF Veteran
Joined: Feb 2010
Posts: 12,367
Likes: 23
From: Oroville, CA
Year: 1995
Model: Grand Cherokee
Engine: 4.0 with all of the noise and clatter
Running without a cat on a 95 will have no ill effect on the PCM, it only has an upstream O2. I would not run without a cat, a hi-flow cat with a Flow Master 40 series is my recommendation.
Thread Starter
Junior Member
Joined: Apr 2013
Posts: 87
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From: Port St. John, Florida
Year: 1995
Model: Grand Cherokee
Engine: 4.0L I6 Power Tech Engine
Thanks guys! I do plan on moving up to Ohio next year so I probably should just buy a Cat and Flowmaster so that way I know I can pass if I have to :P
Whats the name of the cat you used Dave? I have connects in Napa so I might even be able to get it cheaper then you :P
Whats the name of the cat you used Dave? I have connects in Napa so I might even be able to get it cheaper then you :P
Old fart with a wrench
Joined: Nov 2010
Posts: 14,398
Likes: 740
From: Manlius, east of Syracuse, NY
Year: 2000 XJ Sport & WJ Laredo
Model: Grand Cherokee (WJ)
Engine: 4.0L
IDK the part number but I was told it is a universal fit for the Chevy S10 pickup. I think it was only $45 and I bought 2 for my big honking 350 HO. This was also in 1997. My truck was an '89 Laredo short box 4X4 pickup. That thing was a tank, but it wouldn't go where my buddy's Wrangler would. That's why I finally bought a jeep! I had 33x12.5s on it and it didn't even need a lift.
Last edited by dave1123; Jul 25, 2014 at 07:10 AM.
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