convertors plugged again!
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convertors plugged again!
My truck is a 91 F-150 4x4 with a LOT of miles on it. I mean a whole lot!
I have replaced the convertor assembly 4 times now since I bought it new in 1990 and am about fed up with them. It still looks a and runs perfect but is now registered as my farm vehicle so I can get away with a few mods I couldn't before.
The problem is my cats are plugged up again. Well I'm almost certain that's what it is. It has power to spare when I leave here but after about 10 miles when it gets fully warmed up it totaly loses power and will limp home going about 30 MPH if I'm lucky. It's not the fuel pump. I tried switching tanks and I ran it with the pressure gauge mounted and hanging unde the windshield wiper also. It's backfired a couple times too. I haven't got the rotten egg smell yet but I'm sure it will if I push it.
So assuming it is the cats I want to replace the y pipe with one that doesn't have them. I have done all this before in fact and learned some lessons. The first time I put mac headers on it and custom made a y pipe but those headers cracked within 20000 miles and leaked so bad I couldn't stand it. Then I tried a set from ford and they were just as bad. After getting fed up I bought a new set of cast iron manifolds and a new y pipe from ford and had it all back nice and factory like for the last 5 years. It doesn't get used a lot anymore unless I am hauling hay or feed but occcasionaly I go on a hunting trip or something dragging my jeep behind and I really need my power back.
Can anyone help me find the correct factory fit (non cat) Y pipe that will bolt up to the factory exhaust manifolds? My truck does have the air injection tube in the pipe and the O2 sensor bung in the crossover if that helps any.
Originaly it's a california model but that has long since changed.
For about the last 10 years and hundreds of thousands of miles the engine has been converted to the ford motorsport mass air system. It's an awsome little engine for a 302. I just have to deal with this cat problem to be perfect again.
Thanks.
Dan
I have replaced the convertor assembly 4 times now since I bought it new in 1990 and am about fed up with them. It still looks a and runs perfect but is now registered as my farm vehicle so I can get away with a few mods I couldn't before.
The problem is my cats are plugged up again. Well I'm almost certain that's what it is. It has power to spare when I leave here but after about 10 miles when it gets fully warmed up it totaly loses power and will limp home going about 30 MPH if I'm lucky. It's not the fuel pump. I tried switching tanks and I ran it with the pressure gauge mounted and hanging unde the windshield wiper also. It's backfired a couple times too. I haven't got the rotten egg smell yet but I'm sure it will if I push it.
So assuming it is the cats I want to replace the y pipe with one that doesn't have them. I have done all this before in fact and learned some lessons. The first time I put mac headers on it and custom made a y pipe but those headers cracked within 20000 miles and leaked so bad I couldn't stand it. Then I tried a set from ford and they were just as bad. After getting fed up I bought a new set of cast iron manifolds and a new y pipe from ford and had it all back nice and factory like for the last 5 years. It doesn't get used a lot anymore unless I am hauling hay or feed but occcasionaly I go on a hunting trip or something dragging my jeep behind and I really need my power back.
Can anyone help me find the correct factory fit (non cat) Y pipe that will bolt up to the factory exhaust manifolds? My truck does have the air injection tube in the pipe and the O2 sensor bung in the crossover if that helps any.
Originaly it's a california model but that has long since changed.
For about the last 10 years and hundreds of thousands of miles the engine has been converted to the ford motorsport mass air system. It's an awsome little engine for a 302. I just have to deal with this cat problem to be perfect again.
Thanks.
Dan
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Joined: Jan 2006
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From: The dark carnival
If you are going through cats like this, you are probably running rich...meaning that unburned fuel is entering the cat(s) and it is burning inside of them and thus melting them. According to what I have read and been told, 02 sensors are the main culprit for cat failure. I would look into WHY they are failing before getting rid of them. The cat failure is likely to be a syptom of a larger problem.
As for getting rid of the cats, just cut them out and weld in pipe in their place. Where I live, any muffler shop will put a Y-Pipe in the place of the first cat, then install a bigger cat in the place of the second cat that can do the job of both. The second cat is the easier of the 2 to eliminate for a DIY person because it has 1 inlet and 1 outlet.
Have you diagnosed this problem with a vacuum guage to tell for sure if this is a back pressure issue? A plugged cat does not care if the engine is cold or hot (at least it did not in my case), so if the problem comes and goes based on engine temp. you probably have other issues.
As for getting rid of the cats, just cut them out and weld in pipe in their place. Where I live, any muffler shop will put a Y-Pipe in the place of the first cat, then install a bigger cat in the place of the second cat that can do the job of both. The second cat is the easier of the 2 to eliminate for a DIY person because it has 1 inlet and 1 outlet.
Have you diagnosed this problem with a vacuum guage to tell for sure if this is a back pressure issue? A plugged cat does not care if the engine is cold or hot (at least it did not in my case), so if the problem comes and goes based on engine temp. you probably have other issues.
