There are only two cats on these vehicles. Doesn't matter if you have the 4.6 or the 5.4.
The cats are "TWC" converters, as in Three-Way-Catalytic converters. Each converter contains two chambers - the first chamber contains the "reduction" catayst while the second chamber contains the oxidation catalyst. People often think they are looking at four converters, depending on how the outter shell is designed.

 

Ah. Gotchya! Ok, yeah, there is a big shield over them so I can't actually see what they look like so I never noticed more than one.

 

PDQFord, I looked up Three Way Cats, and that is not what I have. I will check again tomorrow and maybe get a picture, but I know I have 4 separate cats, the first 2 maybe 12" of pipe from the headers if I remember correctly, one on each side, and then 2-3 more inches of pipe coming out from them and into 2 separate cats, one on each side.

 

I found a diagram of the exhaust system in my Ford Workshop manual - Section 309-00 (but I don't know how to grab a screen shot and post it!).

Isn't the short 2-3 inches of pipe just a continuous pipe? No joint.? No way to spearate the two chambers?

Go here -

bobutterfordparts.com and look in the exhaust section.

They only list a left converter and a right converter. Interestingly, the 4.6 and the 5.4 use different converters, as do the 2WD and 4WD.

Let me know what you find - you may have an unusual Expy!

 

Haha I wouldn't mind having four cats, more money for me when I sell them haha. I don't think it is a continuous pipe, but I will check tomorrow.

 

you only have 2 cats

 

Missouri on has visual checks. They only look to see if you have a cat. If theres 4 cats and you replace with only 2 it will probably be a bit louder. If you gut them then yes alot louder. Ive ran fake cats on my old dsm's. They looked like a cat but only had a straight pipe in the middle of them.

 

And as the 2 cats only my old mustang had 4 seperate cats also. I havnt looked under my navigator yet. But it seems i would think they would if the mustang 4.6.

 

Any decent muffler shop can replace either bank (left or right) cat assembly for about $175-$225 per side installed regardless of what style of cat you have (single chamber or two-way) (some states won't let you use aftermarket cats so may need to use OEM Cats for about 5 times that or drive out of state to get the repair done).

Since the mandate of OBD-II in 96/97 the only thing the downstream (rear) O2 sensors are for is to tell the computer when the catalytic converters start to get clogged or melt as they start sensing a signal that lags the signal on the upstream O2 sensors. The cheap $80 Magnaflow cats are not a good idea on these engines as this engine needs high flow cats that run around $125-$150 if you want to do it right.

 

YES I HAVE A 1997 EXPO AND IT HAD A MAJOR CAT PROBLEM. THERE WERE 4 CATS ON THERE. IT WAS ALL CLOGGED UP LOOKED LIKE CEMENT IN THERE. I BELIEVE THE PROBLEM CAME FROM BAD O2 SENSORS WHICH I ALSO REPLACED ALL 4. I CUT THE BACK 2 CATS OFF AND RAN STRAIGHT PIPE FROM THERE BACK TO THE MUFFLER AND ALSO CLEANED OUT THE MUFFLER. THAT TRUCK STARTED RUNNING LIKE A MUSTANG!!!!! NICE PEP. ALSO MY GAS MILAGE WENT FROM 12 MPG To 16.5 MPG HIGHWAY AND IT HAS OVERSIZED WHEELS!!!!! IF YOU DONT HAVE TOUGH EMISSIONS LAWS. GET RID OF THOSE CATS. YOU'LL THANK ME LATER!!!!!

BANGER

 

I have a 2000 navigator. it makes a slight noise in the muffler. Saw the car under the bridge today, and there are no cats, straight 2 pipes to the muffler. My mileage sucks 8.8 gallon. muffler shops advices to put silencers in where the 2 cats were. Ok, it will help with the slight noise, but how about mileage? I want better mileage. I cant believe previous poster that says open cats give better mileage. I called my mechanic and he suggested me to do it, that it would give some backpressure and better mileage. Now i am confused, is an all open pipe not the best? but loud? I dont want the noise and better mileage. pls hlp. thanks

 

[QUOTE=widebody95;8794528]I'm 99% sure that I have a cat failure on my 98 5.4L Expy. I am a college student so I'm looking for the cheapest route possible. I was thinking about getting two universals (one per side) instead of replacing the 4 OEM's and spending big $$ doing it. Are there any potential problems with this route that I might be overlooking??

Thanks,
James[/QUOTE

Ok i have a 97 5.4 yes there is 4 cats i just replaced two on my truck it cost me 275 dollars parts and labor with a warrantee on theyre work better than the big chain shops who wanted 1200 i recommend stay away the big chain shop find urself a shop that deals with exahaust only no oil changes nothing else but exhaust cime out better in long run with the original expys like urs there are 4 cats and if u find a good shop they can test and see which cats is failing but trust everybody with early year expys u have 4 cats and if u decide to straight pipe it now ur area emissions laws because u will never pass again good luck