94 Exhaust system questions (1 Viewer)

[Elkwagn]

I've been doing a bunch of searching, but have not yet found an answer. It seems like every post I see on an 80 exhaust system has 2 cats, and mine has one with a Y pipe from the manifolds into it, and then single out that travels up and over the frame. Looking to replace the system, which looks terribly inefficient btw. Currently has a Magnaflo muffler that is louder than I like and what appears to be the original cat.

 

[ppc]

@Elkwagn, Stock ODB1 93-94 models used two cats side by side with one O2 sensor in front of each cat. Each cat handles 3 cylinders. The 93-94 has the preferred routing above the frame.
Stock ODB2 95-97 models used two cats inline with one O2 sensor in the front and the second between the cats. The 05-97 routing under the frame is what you seem to be describing.
Your single cat system is an aftermarket version used on the 95-97 most likely made by Magnoflo or Bosal who was bought out by Maganaflow. In order to use that on a 94 then there is going to be some voodoo that was done to have the proper O2 configuration.

You should post some pictures of what you have including the O2 sensors so we can evaluate what you have.

 

[Rifleman]

Below you will find 2 links, one deals with the issues i had with trying to replace my stock muffler, with whats currently available as a bolt in from the aftermarket.

Next, if you live some place where you don't have to do emission testing, and since you own a 94 you'll find a link to a thread that talks about deleting your cat. In that thread i post about a set of test tubes i made to replace the cats on my 94, and the results i got from installing them.

Post in thread 'Bolt in Factory muffler replacement'

Jan 1, 2025

Well i wanted to update my post with some good news, along with some bad news,

The bad news first, below you'll find 3 photos showing what the current aftermarket bolt in BRexhaust and Ansa mufflers for our trucks look like, Just as an FYI, both the BRexhaust, and the Ansa mufflers use the exact same order part number 228-239, and also have an exact same part number stamped into the muffler body P/N172423,

Size wise you can see the aftermarket muffler body is way shorter in length next to my factory muffler, to the tune of 7 5/8 inch's shorter (16 inch's OAL for the BRexhaust, to 23 5/8...

• Rifleman

Post in thread 'Deleting Catalytic Converters 1994 FZJ80'

Jan 19, 2025

Just wanted to give everyone an update, I know some members wanted to know if removing their cats, and installing a set of test tubes would make any difference in performance,

Well i took my truck for a 200 mile test drive after removing my cats and installing test tubes in their place, This test drive was done on an up, and down hill 2 lane road, speeds running anywhere between 45 MPH to 70 MPH,

Before starting my test i filled up my gas tank, and upon returning home i filled it up again, I use to get 9 to 10 miles per gallon, and my water temps ran between 180 to 185 degrees, My water...

• Rifleman

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[Elkwagn]

Routing is above the frame, looks original to me. Maybe there's two cats in there? hard to tell with the skid plate that's protecting it!

 

[Rifleman]

Yes you have 2 cats under that sheet metal shield.

 

[Elkwagn]

I found this, apparently there ARE two cats hiding in there! Only thing I "need" right now is to replace the muffler and tailpipe, but I may yank the cats. No inspections here

 

[Rifleman]

Make sure you read my post above about the current aftermarket muffler options. The new ones are WAY SMALLER in size, and length, so they are going to be way louder then the stock muffler.

Plus if you plan on deleting the factor cats save the exhaust flanges off of it. When i made a set of test tubes i looked all over for a set of exhaust flanges that match the factory exhaust pipes but i could not find them anywhere, so i had to make a set.

 

[efjayatee]

@Elkwagn, Stock ODB1 93-94 models used two cats side by side with one O2 sensor in front of each cat. Each cat handles 3 cylinders. The 93-94 has the preferred routing above the frame.
Stock ODB2 95-97 models used two cats inline with one O2 sensor in the front and the second between the cats. The 05-97 routing under the frame is what you seem to be describing.
Your single cat system is an aftermarket version used on the 95-97 most likely made by Magnoflo or Bosal who was bought out by Maganaflow. In order to use that on a 94 then there is going to be some voodoo that was done to have the proper O2 configuration.

You should post some pictures of what you have including the O2 sensors so we can evaluate what you have.

I just replaced my 2 cats on my 96, my O2 sensor is after the #2 cat and the other O2 sensor is before the 1st cat,p. My 2 cats are between the O2 sensors.