Kelton

I drive a 94 f150 4x4 with the 351W, Im looking to do some exhaust work soon, I was thinking straight pipes with long glass packs to keep it at least somewhat under control.... But I know the emissions system is a little crazy on the EFI, I'm looking to delete the cat and resonator, or at least the cat, so I've been searching for white awhile but I can't find any solid guides on what to do! I'm a pretty decent welder, and I've got the equipment so that's not an issue, but I heard, between the can and the resonator, there's a pipe inside of the pipe between the two! What do I do with that and what will I need to do with the sensors?
PS, where I live, my truck is too old to qualify for emissions testing, so that's no worry!

Any help would be awesome,
thanks y'all!

Ford 4x4

You should have the 02 sensor and the AIR tube. I think the 351w has the 02 before the cats. you can just leave the AIR tube hanging, it will just blow air out of it.

Warlockk

There is no resonator. The first cat handles NOx, the second handles HC and Co. There is no instructions on it because removing smog equipment is a federal offense. The AIR tube is useless if you remove the cats. Don't reconnect it or it may burn a hole in your exhaust. Leave the upstream tubes and they will continue to reduce HC. If you have a downstream sensor, it will activate the cel, but I think the 94 351 has only an upstream sensor.

dr_bowtie

glass packs are too restrictive... get better mufflers

Kelton

Ok thanks! So the sensor in the first cat is required? Im no good with emissions stuff.... The air tube, that's the tube welded into the inside if the pipe between them?

Warlockk

The sensor before the cats must be there. The second sensor, if equipped, is there to monitor the cat. It also checks the function of the AIR system. Yes the tube between the cats or sometimes in the first cat is the secondary air system ( AIR ). It also has a tube that goes to the back of the heads. The air ( smog ) pump sends air down the tubes to either tube or out to atmosphere through the funny looking muffler on the fender in the engine compartment depending on engine load and temperature.

Just call me Sean

iTrader: (1)

Only the '96 5.8 has more than one oxygen sensor.

Warlockk

Thanks wasn't sure on the 5.8.

Kelton

Ok, thanks alot, I think I got it, rear cat can be removed without any issue, should I re route the air tube in the pipe to blow outside? Or can I just weld my new exhaust pipes straight to it and let the air tube blow into the new pipes with with rest of the exhaust?

Ford 4x4

I would get rid of both cats if you have them, or the cat and resonator. Leave the air tube disconnected if you do not have the cats on the truck, i heard it will burn a hole in the new exhaust if no cats are there.