3rd Cat Removal effect on Emissions - TCCoA Forums
 
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post #1 of 16 (permalink) Old 03-17-2008, 09:08 PM Thread Starter
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3rd Cat Removal effect on Emissions

Will removing the 3rd cat have much of a negative effect on emissions output?

I'm in NY where the laws fairly strict. I'd like to go with just two high-flow front cats and remove the 3rd.

79 TBird 5.0 - wrecked - driven 3 months
79 Mustang Pace Car 4cyl Turbo - sold to collector - driven 1 1/2 years
89 Cougar 3.8 - head gasket @ 141k - driven 1 yr
90 Cougar 3.8 - needed complete front susp @ 159k - driven 4 years
93 Cougar 3.8 - leaky head gasket @ 127k, bad front susp - driven 3 years
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post #2 of 16 (permalink) Old 03-17-2008, 09:18 PM
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I removed mine and went through state inspection (New Jersey) with flying colors.

not all of them came with 3 cats

I've come into this world with nothing and still manage to have some of it left.

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post #3 of 16 (permalink) Old 03-17-2008, 09:24 PM
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Quote:
Originally Posted by ClintD View Post
not all of them came with 3 cats
All 4.6L cars did.

As far as passing emissions testing, I did it here in CA without the 3rd. If it can be done in CA, it can be done anywhere. The only threat is the visual inspection.

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post #4 of 16 (permalink) Old 03-17-2008, 11:47 PM
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AFAIK, OBDII cars in NY do not need to pass a sniffer test. They just hook a scanner up to the test port and the car's computer tells the inspection computer if it passes or not. Usually, as long as you are not throwing codes, you should be fine.

As for the cats themselves, the computer only sees the front two cats, so you could remove the 3rd and put on a y pipe with no troubles. On my car (which used to pass NY emissions very well with this setup) I removed all three cats. The OEM front two are two stage cats (hydrocarbon and CO) while the 3rd is a three stage (hydrocarbon, CO, and NOx). I replaced all three with two three stage high flow cats. My first sniffer test with this setup (in 2003) was better than its first inspection in 1994.

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post #5 of 16 (permalink) Old 03-18-2008, 11:25 AM Thread Starter
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Awesome replies, thanks for the confirmation.

For the record, my 95 is not OBDII. I believe that started in 96.

79 TBird 5.0 - wrecked - driven 3 months
79 Mustang Pace Car 4cyl Turbo - sold to collector - driven 1 1/2 years
89 Cougar 3.8 - head gasket @ 141k - driven 1 yr
90 Cougar 3.8 - needed complete front susp @ 159k - driven 4 years
93 Cougar 3.8 - leaky head gasket @ 127k, bad front susp - driven 3 years
-
95 TBird 4.6 - crashed at approx. 150k - SOLD to TCCOA member to be fixed.
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post #6 of 16 (permalink) Old 03-18-2008, 02:19 PM
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the 4.6 birds got OBDII in 94

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post #7 of 16 (permalink) Old 03-18-2008, 03:11 PM
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while your 95 is OBD-II it won't be treated as such when getting emissions done more than likely (here in AZ you would have to hook up to the sniffer and go on the rollers, while my 97 and 00 it is hooked up to the diagnostic port only. NO VISUAL at all, don't look under the hood under the car, just the gas cap).

--
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post #8 of 16 (permalink) Old 03-18-2008, 03:48 PM
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Quote:
Originally Posted by Johnny Cougar View Post
The OEM front two are two stage cats (hydrocarbon and CO) while the 3rd is a three stage (hydrocarbon, CO, and NOx).
Where did you get this information? All 3 of mine are 3-way cats.

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post #9 of 16 (permalink) Old 03-18-2008, 05:45 PM
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Those Ford Manufactures Motor Vehicle Specification PDF files show all three are three way cats.

I don't think there has been a two way cat on a gas powered vehicle since early 1980s.

--
97 Mark VIII LSC/Silver/Gray leather
97 Cougar 4.6 Sport/White Opalescent Tricoat Metallic /Gray leather down but not out?
89 Cougar LS 3.8/Oxford White/Gray velour/HG need replaced AGAIN
00 Grand Marquis LS/Vibrant White/Gray velour
63 Falcon 302/black and rust/shed isn't moving
82 F-150/Oxford White/dumb VV carb doesn't pass emissions
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post #10 of 16 (permalink) Old 03-18-2008, 05:53 PM
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My '92 Cougar with the 3.8 only has two cats. There is a resonator after the cats. A lot of people mistake the resonator as a third cat.
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post #11 of 16 (permalink) Old 03-18-2008, 06:33 PM
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How did this get on the topic of the number of cats the car has? We were talking about the functionality of the cat (2-way vs. 3-way). All 4.6L cars came with 3 cats. I believe all CA cars came with 3 cats, and all OBDII cars came with 3 cats. What I was originally saying is that none of them are 2-way cats, like someone had said earlier.

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post #12 of 16 (permalink) Old 03-18-2008, 08:26 PM Thread Starter
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Quote:
Originally Posted by 94MN1246 View Post
the 4.6 birds got OBDII in 94

-John
Quote:
Originally Posted by Bangster View Post
while your 95 is OBD-II it won't be treated as such when getting emissions done more than likely (here in AZ you would have to hook up to the sniffer and go on the rollers, while my 97 and 00 it is hooked up to the diagnostic port only. NO VISUAL at all, don't look under the hood under the car, just the gas cap).
You both tweaked my curiosity. I purchased an Actron CP9145 several months back for my wifes car. When purchasing there was optional OBDI cable available for up to 1995 fords. So I figured that meant me (I didn't buy it). I just now found on the Actron website a list of Ford/Lincoln/Mercury 94-95 vehicles that are OBDII Compliant, and YES the 94 and 95 4.6 birds are OBDII.

So thanks John, I'm excited to go scan my car now.

Anyway, Bangster, why do you say it won't be treated as such. You are right for whatever reason as I do still get the old style NY State inspection. Why is this the case if the car is OBDII? Maybe they're mistaken like I was thinking that it started in 96?

-
hopefully this link will work: (page 2 of pdf)
http://www.actron.com/media/categori...128_CP9131.pdf

-

79 TBird 5.0 - wrecked - driven 3 months
79 Mustang Pace Car 4cyl Turbo - sold to collector - driven 1 1/2 years
89 Cougar 3.8 - head gasket @ 141k - driven 1 yr
90 Cougar 3.8 - needed complete front susp @ 159k - driven 4 years
93 Cougar 3.8 - leaky head gasket @ 127k, bad front susp - driven 3 years
-
95 TBird 4.6 - crashed at approx. 150k - SOLD to TCCOA member to be fixed.

Last edited by sabarth; 03-18-2008 at 08:30 PM. Reason: add url
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post #13 of 16 (permalink) Old 03-19-2008, 11:05 AM
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Quote:
Originally Posted by master486 View Post
How did this get on the topic of the number of cats the car has? We were talking about the functionality of the cat (2-way vs. 3-way). All 4.6L cars came with 3 cats. I believe all CA cars came with 3 cats, and all OBDII cars came with 3 cats. What I was originally saying is that none of them are 2-way cats, like someone had said earlier.

Because the original poster asked:
Quote:
Will removing the 3rd cat have much of a negative effect on emissions output?

I'm in NY where the laws fairly strict. I'd like to go with just two high-flow front cats and remove the 3rd.

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post #14 of 16 (permalink) Old 03-22-2008, 07:09 PM
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I cut my resonator out tonight while playing under the car to see how much louder it would be. It was a waste of time imho with the three cats still there!
I'm going to look into two high flow cats and delete the third as well like sabarth is thinking.
I see master486 passes with only two cats, so I will look into this further as well.
Anyone else running just two cats and go through emmisions, please let us know how you do too please

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post #15 of 16 (permalink) Old 03-23-2008, 08:12 PM
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Soo on my 96 4.6 I have the two cats up fron't and that ones right behnd the back seats so to speak then the mufflers near the back bumer? Assuming that thing by the back seats under the car is a cat, doers it help performance at all to be removed?

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post #16 of 16 (permalink) Old 03-24-2008, 01:39 AM
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Quote:
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Assuming that thing by the back seats under the car is a cat, doers it help performance at all to be removed?
Not really.

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