f150_fx4 said:

Ya lol. Just showed my dad this video. He was like you just need a good set of headers Im like you going to pay for them. He said no. But he was like your truck probably sounds like that already Im like no this one has the rear two cats removed. He was like o so you just got to remove them some how. I told him my plan and he sounded like he didnt care. So hopefully in the next few weeks I can get it done.

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Sounds good. If he wasn't cool with it he would have told you so. Good luck.

No I payed for it. He cosigned though. I know its my truck and whatever but I dont wana hear him complain everytime I get up to goto work in the morning and I wake him up with my truck. Its just one of them things I wana make sure they are ok with it before I do it since I am living in their house. Till I can get enough money for my house.

f150_fx4 said:

No I payed for it. He cosigned though. I know its my truck and whatever but I dont wana hear him complain everytime I get up to goto work in the morning and I wake him up with my truck. Its just one of them things I wana make sure they are ok with it before I do it since I am living in their house. Till I can get enough money for my house.

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ohhh ok, yeah... I guess your a little more considerate than me then haha

But, if they started complaining to me, I could just start mine, move it where i start over the hill, kill it... then start it agian at the bottom. Problem solved (for the most part)

That F150 sounds so sweet. I love it. It sounds almost like an old school muscle car. Or not. Whatever, it sounds great.

There is a lot of miss-information in this thread. The 2004 F150 has 4 cats 2 on each side, with the O2 sensors between the front and rear cats. You can cut the back 2 cats off and the computer will never know. I know multiple people who have done this mod, and I've been considering it as well.

Check this truck out. 2004 with deleted rear cats and a single chamber flowmaster. Sounds nasty.

http://www.youtube.com/watch?v=lGi0mppGa4E&feature=fvw

http://www.youtube.com/watch?v=N0keTNpMrG0&feature=related



And here is a good read on what to do. Again, a guy with a 2004.

http://www.f150online.com/forums/exhaust-intake-systems/343787-finally-deleted-rear-cats.html

mSaLL150 said:

There is a lot of miss-information in this thread. The 2004 F150 has 4 cats 2 on each side, with the O2 sensors between the front and rear cats. You can cut the back 2 cats off and the computer will never know. I know multiple people who have done this mod, and I've been considering it as well.

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I'm going to take issue with the "your computer will never know" part of that statement. I can almost guarantee you it will, and you'll be replacing them in states that run smog checks. Figure about a grand, since most doon't keep the cats after they cut them off.

I see no one has mentioned getting a programmer and having it written for use without cats. Is there not one out for the new F150's yet? There has to be someone writing an "offroad use only" program for them..

polarbear said:

I'm going to take issue with the "your computer will never know" part of that statement. I can almost guarantee you it will, and you'll be replacing them in states that run smog checks. Figure about a grand, since most doon't keep the cats after they cut them off.

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After 4 years and the better part of 80k miles without the rear cats on my friend's 2004, I can absolutely guarantee you the computer on the 04-05 f150 will not know. On the 06 and up trucks it will since they switched to 2 cats instead of the 4 cats system.

mSaLL150 said:

After 4 years and the better part of 80k miles without the rear cats on my friend's 2004, I can absolutely guarantee you the computer on the 04-05 f150 will not know. On the 06 and up trucks it will since they switched to 2 cats instead of the 4 cats system.

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'Xplain to me how the '04-'05's pass Cali smog? They won't up here without all cats intact- but here's the kicker. They don't do a sniff test, they just plug into the OBD connection under the dash. And yeah- the computer knows.

What am I missing?

polarbear said:

'Xplain to me how the '04-'05's pass Cali smog? They won't up here without all cats intact- but here's the kicker. They don't do a sniff test, they just plug into the OBD connection under the dash. And yeah- the computer knows.

What am I missing?

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Well seeing as you have never done it in person, I dont see how you are so sure the computer will know. Do you even have an 04-05 F150?! If yes, go crawl underneath it and look at the location of the O2 sensors. It will not pass CA smog tests without rear cats, but those are only required every 5 years (and it helps to know people in the business...CA smog is BS). Plugging into the OBDII port will not show a code for missing rear cats as the computer will never detect it in the first place. Let me ask you this: without O2 sensors behind the rear cats (or ANY monitoring device for that matter), how is the computer supposed to detect them missing?!

mSaLL150 said:

Well seeing as you have never done it in person, I dont see how you are so sure the computer will know. Do you even have an 04-05 F150?! If yes, go crawl underneath it and look at the location of the O2 sensors. It will not pass CA smog tests without rear cats, but those are only required every 5 years (and it helps to know people in the business...CA smog is BS). Plugging into the OBDII port will not show a code for missing rear cats as the computer will never detect it in the first place. Let me ask you this: without O2 sensors behind the rear cats (or ANY monitoring device for that matter), how is the computer supposed to detect them missing?!

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I agree if the rear sensor is in front of the rear cat the computer does not detect a cat. code for rear cat. If there is a sensor behind rear cat and you want to remove your cat. feel free to google "o2 eliminator". However I personally think it is not always the best thing to remove your cat, but it is your vehicle and you can do as you wish. You should hang onto the cat in case you find you need to put it back. That will save you some money.

mSaLL150 said:

Well seeing as you have never done it in person, I dont see how you are so sure the computer will know. Do you even have an 04-05 F150?! If yes, go crawl underneath it and look at the location of the O2 sensors. It will not pass CA smog tests without rear cats, but those are only required every 5 years (and it helps to know people in the business...CA smog is BS). Plugging into the OBDII port will not show a code for missing rear cats as the computer will never detect it in the first place. Let me ask you this: without O2 sensors behind the rear cats (or ANY monitoring device for that matter), how is the computer supposed to detect them missing?!

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Manifold pressure sensors, exhaust back pressure sensors will allow the computer to know of the change/problem, there is more to these engines and computers than just O2 sensors. Changing anything in the exhaust or intake, changes the air flow characteristics of the engine and then the sensor readings change. An engine is just an air pump.

Just an FYI FMC was one of the first manufactues to adopt enhanced computer codes and they did this starting in MY 2004. Most generic OBDII code readers will not read the enhanced codes or monitor real time sensor data. However, dealer, smog test and advanced computer diagnostic equipment will read all sensors & moitor real time data.

As far as Polarbear owning and knowing about Ford trucks and F150's he is more knowledgeable about these vehicles than most people, he has extensive experience with them and has owned & been around several of them and that includes the last 20+ model years up through 2009.

It is nice to see you are getting your vehicles to pass CA emissions by paying off the inspector, but this does not mean that modifying the vehicle had no effect.

blackhat620 said:

It is nice to see you are getting your vehicles to pass CA emissions by paying off the inspector, but this does not mean that modifying the vehicle had no effect.

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My truck is smog legal. My friend's has years and many miles without rear cats. Just speaking personal experience here man, not trying to pretend I know every little thing about the truck. Sure, there may be little things here and there but I have never encountered someone who's had a problem removing rear cats on a 2004 F150. But go ahead, you can continue taking shots at me over an internet forum; All I did was state my opinion and ask a question.

mSaLL150 said:

My truck is smog legal. My friend's has years and many miles without rear cats. Just speaking personal experience here man, not trying to pretend I know every little thing about the truck. Sure, there may be little things here and there but I have never encountered someone who's had a problem removing rear cats on a 2004 F150. But go ahead, you can continue taking shots at me over an internet forum; All I did was state my opinion and ask a question.

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Actually, it's not smog legal. Here's an important difference though. In Cali, you get smogged typically by independent stations. Not so Oregon. I'd like to have a dollar for every used car and truck we (the dealership) bought over the years that had Cali certification, but would not pass an Oregon DEQ test. It's laughable, because Cali standards are stricter, but their enforcement sux.

As already mentioned- your truck, your dime. In some parts of the country you can slip by- just don't think you can everywhere.

polarbear said:

Actually, it's not smog legal. Here's an important difference though. In Cali, you get smogged typically by independent stations. Not so Oregon. I'd like to have a dollar for every used car and truck we (the dealership) bought over the years that had Cali certification, but would not pass an Oregon DEQ test. It's laughable, because Cali standards are stricter, but their enforcement sux.

As already mentioned- your truck, your dime. In some parts of the country you can slip by- just don't think you can everywhere.

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Dude my truck has all 4 cats from the factory, untouched. The only thing modified is the muffler and intake, which are both CARB certified. It would pass with flying colors.

mSaLL150 said:

Dude my truck has all 4 cats from the factory, untouched. The only thing modified is the muffler and intake, which are both CARB certified. It would pass with flying colors.

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Ah- I was understanding you took two cats off of your truck. My bad.

The way our DEQ (Dept of Enviornmental Quality) works, they tap into the computer and check 1) actual emissions 2) verify the programming is OEM (now there's a can of worms) 3) will physically verify all emissions devices are present and operating as designed.

Intake wouldn't/shouldn't cause an issue as long as the rest of the fuel delivery system is stock. By the same token, you wouldn't believe what doesn't pass. Makes CARB look like a bunch of schoolgirls.

polarbear said:

Ah- I was understanding you took two cats off of your truck. My bad.

The way our DEQ (Dept of Enviornmental Quality) works, they tap into the computer and check 1) actual emissions 2) verify the programming is OEM (now there's a can of worms) 3) will physically verify all emissions devices are present and operating as designed.

Intake wouldn't/shouldn't cause an issue as long as the rest of the fuel delivery system is stock. By the same token, you wouldn't believe what doesn't pass. Makes CARB look like a bunch of schoolgirls.

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Ah, that makes sense. And yes I think the whole CARB certification thing is a silly waste of time and money.

Well maybe you can answer this question then: I know they dont check for this in CA, but I do run a custom dyno tune on my computer. This is to help correct the A/F ratios since the aftermarket intake had the truck running lean. It also helps the transmission shift a lot firmer, reducing heat and hopefully helping it last longer. Not to mention the extra ~40 horsepower is helpful to turn the 35s.

Now, this dyno tune is much "safer" than the stock tune and would actually be cleaner on the sniff test. However, I do not believe it is legal to alter the computer in CA. So say if I did have to get it checked...I have heard you can re-upload the stock OEM tune and drive it for a couple hundred miles to get the adaptive learning intact....and the computer will not show a code that shows a different program on there previously. Is this true?

mSaLL150 said:

I dont see how you are so sure the computer will know................ Plugging into the OBDII port will not show a code for missing rear cats as the computer will never detect it in the first place. Let me ask you this: without O2 sensors behind the rear cats (or ANY monitoring device for that matter), how is the computer supposed to detect them missing?!

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The computer will see a difference in data. Will it set a dtc? Maybe/maybe not. The rear sensor is there for catalyst monitor. How does it detect or see the rear cat missing? Backpressure......the rear cat causes a buildup of pressure that the sensor can see the gas more readily. We had traded in an f150 that the rear cats were removed. Using a graph for the o2 sensors, it took the rear sensors an extra long time to register any exhaust gasses (a good tech will see a problem using this alone). This particular vehicle had pipes welded in where the cats should be. One of the welds actually killed one of the downstream sensors (which showed on the graphs)

mSaLL150 said:

Ah, that makes sense. And yes I think the whole CARB certification thing is a silly waste of time and money.

Well maybe you can answer this question then: I know they dont check for this in CA, but I do run a custom dyno tune on my computer. This is to help correct the A/F ratios since the aftermarket intake had the truck running lean. It also helps the transmission shift a lot firmer, reducing heat and hopefully helping it last longer. Not to mention the extra ~40 horsepower is helpful to turn the 35s.

Now, this dyno tune is much "safer" than the stock tune and would actually be cleaner on the sniff test. However, I do not believe it is legal to alter the computer in CA. So say if I did have to get it checked...I have heard you can re-upload the stock OEM tune and drive it for a couple hundred miles to get the adaptive learning intact....and the computer will not show a code that shows a different program on there previously. Is this true?

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I'm going to defer to Vince (blacksnapon) on this one. I imagine the reset would be the same as all the diesels (ahem) that come in for warranty work. Computers need to be reset to stock before warranty repairs can commence.

FYI- this loops back around to what i was saying before. Aftermarket is getting really tough for these later model trucks.

mSaLL150 said:

There is a lot of miss-information in this thread. The 2004 F150 has 4 cats 2 on each side, with the O2 sensors between the front and rear cats. You can cut the back 2 cats off and the computer will never know. I know multiple people who have done this mod, and I've been considering it as well.

Click to expand...

mSaLL150 said:

After 4 years and the better part of 80k miles without the rear cats on my friend's 2004, I can absolutely guarantee you the computer on the 04-05 f150 will not know. On the 06 and up trucks it will since they switched to 2 cats instead of the 4 cats system.

Click to expand...

mSaLL150 said:

Well seeing as you have never done it in person, I dont see how you are so sure the computer will know. Do you even have an 04-05 F150?! If yes, go crawl underneath it and look at the location of the O2 sensors. It will not pass CA smog tests without rear cats, but those are only required every 5 years (and it helps to know people in the business...CA smog is BS). Plugging into the OBDII port will not show a code for missing rear cats as the computer will never detect it in the first place. Let me ask you this: without O2 sensors behind the rear cats (or ANY monitoring device for that matter), how is the computer supposed to detect them missing?!

Click to expand...

mSaLL150 said:

My truck is smog legal. My friend's has years and many miles without rear cats. Just speaking personal experience here man, not trying to pretend I know every little thing about the truck. Sure, there may be little things here and there but I have never encountered someone who's had a problem removing rear cats on a 2004 F150. But go ahead, you can continue taking shots at me over an internet forum; All I did was state my opinion and ask a question.

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Actually you stated far more than "your opinion", you specifically said that "you would absolutely guarantee the computer on an 04-05 F150 would never know". Then you proceeded to get adversarial with Polarbear, going so far as to say "that since he had never personally done the modification, he could not know what he was talking about". Further you admitted to never having done the modification yourself, but some how are of the belief that you can "guarantee" the computer will never know, and that Polarbear does not have a clue since he has "never personally done the modification". Nice double standard on your part. In addition, you brought up finding a CA inspector that can be convinced to bend the rules as a defense for the computer not knowing.

Before you go playing "Mr Innocent" that feels he has been unduly criticized on a "forum", you may want to re-read and think about your previous posts!