Removing the cat on 4.5

[RGarza]

Does anyone out there have any answers to what will happen if the cat on a 4. 5 was removed. Will there be any codes that come up from loss of back pressure or anything like that. I have heard that the fuel milege will go up, but have not been told of that first hand. If anyone has any answers, I would appreciate it. Thank You, RG

 

[KevinO]

It won't throw any codes, back pressure is less you can feel the boost come on a little quicker but there aren't any mileage increases. It's slightly louder with the stock muffler but not much. I have a magnaflow on order for more noise. I have 5500 miles on it now and mileage 60-70% highway averages about 15-16. Maybe some of these fueling box manufactures can figure out how to get the mileage put back into these truck cause it sucks. My 01 with 320 rwhp and 37" PJ tires got 18 mpg.

 

[GCross]

Best advice is don't do it. You will not see any or very little difference in power or MPG and you will be subject to a fine if caught. I took one off of a car in the 70's and actually suffered an MPG loss. What would be your purpose for doing this? Just curious.

 

[RGarza]

removing the cat

just trying to get a little better fuel milege

 

[RustyJC]

Isn't the 3rd injection event there to get the cat up to temperature? In that case, it looks like the real improvement would be to get rid of the 3rd injection event. Removing the cat won't make that much difference if the fuel is still being injected.



But then again, I have a 2nd generation truck, so what do I know???



Rusty

 

[DPelletier]

Rusty,

That's precisely what I suspect is the issue.



Dave

 

[CJ8Rockcrawler]

Forgive me... . I'm new here and still learning... . The 3rd injection event is only on the 600s, right?

 

[RustyJC]

That's my understanding, but as I said, I'm just a poor, ignorant 2nd generation guy.



Rusty

 

[NDanecker]

Originally posted by CJ8Rockcrawler

Forgive me... . I'm new here and still learning... . The 3rd injection event is only on the 600s, right?

One of the tech people at my dealer said the 555 motors also have a 3rd or post combustion injection event. The 600 one is just longer/different timing then the 555 one. That is what I was told... who really knows for sure.



I predict a tuner will come out with a box that will reprogram these for power and not to be so green. Although I don't understand the rational of a truck that uses 25% more fuel as being so green to the environment. I guess the 25% of extra fuel combusted has less pollutants per volume.



Prffttt………. . I'll opt for power and better MPG anyday!



PS - MBRP dual SS exhaust with cat test pipe due to arrive shortly! Oo.

 

[klenger]

Rusty. What are you doing up here in the high rent district? Go back to where you belong with the classic trucks. Just kidding. Your insite is always appreciated.

 

[RustyJC]

Originally posted by klenger

Rusty. What are you doing up here in the high rent district?

Just think of me as the kid with his nose pressed up against the candy store window! I'm just seeing what's going on with you "girlie diesel" folks.



Rusty

 

[KevinO]

when you bomb your truck you will probably want to get rid of it cause the EGT's rise much faster with more restriction. Just take it off, take a rod knock out the inside and put it back on unless you have emissions testing in your state. They won't know the difference. Diesel's and trucks over 8500 gvw are exempt in MO. Taking a tech's advice is sometimes not worth the pot you p*ss in. The 600 is the only one with the 3rd injection event made to keep the cat at working temps. A tech at the dealer a couple miles from my house argued with me over the fact that the motors on the 600 were 330 hp but i corrected him and said 325 but he said i was wrong.

 

[DPelletier]

Rusty,

That's OK, I periodically "slum around" the 2nd Gen forums!

NJ Tackle,

I am not the omnicient 600 guru by any stretch, but I believe the 555's only have 2 injection events. Wouldn't be the first time the dealer techs were wrong and it sure won't be the last time!



Dave

 

[231jasonS]

Originally posted by GCross

Best advice is don't do it. You will not see any or very little difference in power or MPG and you will be subject to a fine if caught. I took one off of a car in the 70's and actually suffered an MPG loss. What would be your purpose for doing this? Just curious.

GCROSS,

Just who is going to fine you? The only offense you could get fined for by a police officer is for the catch all section "modified exhaust" which any modification of your exhaust system could be. Anyway its a "fix it ticket", no fine $12. 00 court admin fee.



Even if you had to get your truck emission tested it would just fail the visual no fine there either.



just wondering which FBI agents were gonna fine you? Come on the 70's..... things have changed a little since then.

 

[Buzzer]

Actually its not local authorities but the Feds i. e. DOT (emissions laws). If you were to get caught without the cat then you could be fined. How much? Don't know, and whats the odds? Pretty remote unless DOT is especially active in your area. Here in NY where I live they only bother you if your towing something large and then its not often at all, but you do take your chances if you remove the cat.

 

[mattymac]

Do it! no regrets on mine, just dont forget to put a good 4" straight through muffler on too.

 

[mattymac]

Do it! no regrets on mine, just dont forget to put a good 4" straight through muffler on too.

 

[KevinO]

Just take it off rod it out and put it back on the worst you could get if you have emissions is it may fail. They would tell you your cat is not operating properly and you have to fix it. visual inspection it will still be there.