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Why Does My 93 F-150 Have 2-Cats On One Pipe?

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Old 02-22-2000, 07:29 PM
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Question Why Does My 93 F-150 Have 2-Cats On One Pipe?

Ok I was looking at my F150s exhaust while it was up on a rack today and I noticed that it has two catalytic convertors on it. But it's only a single pipe not true duals. One of them is small the other is pretty big. Whats the purpose of the small one?


1993 Ford F-150
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Old 02-23-2000, 11:05 PM
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Old 02-24-2000, 12:32 AM
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I don't know about trucks. but my mustang had 2 cats on each pipe. many stang owners went and swapped them for aftermarket single cats for better flow.

My best guess is for extra emissions


99 F150 Xtracab 4X4 XLT
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Old 02-24-2000, 10:38 AM
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Location: Shakopee, MN
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The first is a pre-converter. Supposedly it was supposed to be extra emmissions. It's perfectly legal to replace it with one unit though. Had the same thing on my 93 and 86.

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Old 02-24-2000, 11:24 AM
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Are you a part of the Ford cat breeding program? Click the image to open in full size.

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[This message has been edited by cphilip (edited 02-24-2000).]
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Old 02-24-2000, 02:10 PM
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Location: Windsor, ON, Canada
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I had the samething on my '87 and '94. I was told the first one (smaller) is a resonator and the second one is the cataltic converter. The mechanic that changed the one out on the '87 said that and the new one that went on only had the one combined (assuming) into the one cat. BTW after the new one went on, a lot better take off (seat of pants) to the truck. But made my own exhaust choice of exhaust about 1 year before cat change and that helpped too. Put a 351 muffler on (single in, dual out) and added the dual tails with chrome tips. Nice look and better take off, might think of that combo instead of true duals. Only cost around $250 at a local muffler shop.

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Old 02-24-2000, 04:21 PM
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Yep its a pre-heater, pre-convertor, whatever. I doubt it does much.



1993 F-150 302/e4od/355 Limited slip. dual exhuast w/o mufflers, 2 1/4" pipes, Echo Tips, Summit Racing headers, accel plugs/wires(8.6mm)/rotor/cap, hypertech powermodule, 4 degree advance,Blaster Coil,MSd 6A Ignition, TPS Mod,hopefully roller rockers in the future,possible 4:10 gear swap 5% dark tint, Ford Bed mat, Bundy Chrome Drop bumper, Wrap-around bug deflector, 2-tone tan/brown. Alpine cd player and Pioneer speakers, with tweeters No room for anything else.

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