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Discussion Starter · #1 ·
My truck is deleted, but I left the cat on to keep it quiet and also for visual inspections, I put a muffler in place of the DPF so it isn’t readily noticeable that it’s been removed. After about 130,000 mile of being deleted my fuel mileage is starting to go down. My mechanic says my cat is probably full of soot since the DEF isn’t being injected to keep the cat clean. I’ve got another cat that’s been cut in front (missing V-band), that I’m going to hollow out and swap out, but after looking under the truck the cat is sandwiched between the trans crossmember and the torsion bar connection/end piece.

How difficult is it to pull the trans crossmember and what do you use to support the trans? Can this be done without a lift?


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My truck is deleted, but I left the cat on to keep it quiet and also for visual inspections, I put a muffler in place of the DPF so it isn’t readily noticeable that it’s been removed. After about 130,000 mile of being deleted my fuel mileage is starting to go down. My mechanic says my cat is probably full of soot since the DEF isn’t being injected to keep the cat clean. I’ve got another cat that’s been cut in front (missing V-band), that I’m going to hollow out and swap out, but after looking under the truck the cat is sandwiched between the trans crossmember and the torsion bar connection/end piece.

How difficult is it to pull the trans crossmember and what do you use to support the trans? Can this be done without a lift?


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the DEF is a reactant to reduce emissions, as far as i am aware it has no bearing on soot buildup in the cat. If your mechanic were correct, all the trucks built before 07 would have clogged up cats every few years. Thats not to say that your cat isnt the issue, it might be, but not because of the DEF.

As for removal, a lift would make life easier but you can do it on jack stands, get a block of wood and a jack to support the transmission, or cut the exhaust so you can remove the cat without taking the cross member out. This is how most i know have done it when adding aftermarket exhaust, not sure how that would impact your semi stock setup though.
 

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what muffler did you use instead of a DPF delete pipe? Got any sounds clips?
 

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My truck is deleted, but I left the cat on to keep it quiet and also for visual inspections, I put a muffler in place of the DPF so it isn’t readily noticeable that it’s been removed. After about 130,000 mile of being deleted my fuel mileage is starting to go down. My mechanic says my cat is probably full of soot since the DEF isn’t being injected to keep the cat clean. I’ve got another cat that’s been cut in front (missing V-band), that I’m going to hollow out and swap out, but after looking under the truck the cat is sandwiched between the trans crossmember and the torsion bar connection/end piece.

How difficult is it to pull the trans crossmember and what do you use to support the trans? Can this be done without a lift?


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Not having the DEF clogging up the cat is a good thing, having only soot is easier to burn off.
You show Motor Ops for tuning do you have the AutoCal where you can do a data log and email them the results.
What’s your balance rates show ?
Are you using any diesel additives, the fuel quality is going downhill?
Are you using bio fuel to high of a % will affect mileage.

What kinda fuel mileage drop are you experiencing?
Weather changes affects mileage.

Drive the front on blocks, 6” would work.
Unbolt the crossmember and slide it out of the way.
Floor jack to support the trans.

Having personal experiences with cat and without cat, without, it’ll be a little louder and mucho diesel exhaust stink that even a aftermarket cat can not handle.

I put mine back on after 5 years of suffering with the stink.
 
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Discussion Starter · #7 ·
what muffler did you use instead of a DPF delete pipe? Got any sounds clips?


I tried to add a video, but there is no video upload on Tapatalk or the mobile website.
There’s a little rumble from 1100-1300 rpm, but that’s all you hear from the inside. On the outside it has a slightly deeper tone, but not much. It’s not any louder than stock on the inside as the engine makes so much noise to begin with.




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Discussion Starter · #8 ·
Not having the DEF clogging up the cat is a good thing, having only soot is easier to burn off.
You show Motor Ops for tuning do you have the AutoCal where you can do a data log and email them the results.
What’s your balance rates show ?
Are you using any diesel additives, the fuel quality is going downhill?
Are you using bio fuel to high of a % will affect mileage.

What kinda fuel mileage drop are you experiencing?
Weather changes affects mileage.

Drive the front on blocks, 6” would work.
Unbolt the crossmember and slide it out of the way.
Floor jack to support the trans.

Having personal experiences with cat and without cat, without, it’ll be a little louder and mucho diesel exhaust stink that even a aftermarket cat can not handle.

I put mine back on after 5 years of suffering with the stink.


I haven’t run a data log yet.

My balance rates are all been -1.5 to +2.2. I have one injector which is at about +2.8.

I run OptiLube XPD at each tank (1 oz. to 4 gallons). We don’t have any biofuel places out here.

On long runs about 100 miles I’ll get about 16.5-17 mpg running about 80mph. Now I’m getting about 14.5 on a 35 mile run back and forth to work now. When I first deleted I was getting around 19mpg at 80mph.

I’m in SoCal so we really don’t have much of temperature changes.


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Discussion Starter · #9 ·
I'm sorry, I didn't hear your question. I was distracted by your wonderful Avitar.


Believe it or not someone PM’d me saying it was offensive to them and wanted me to change it.
What a h**o.


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Believe it or not someone PM’d me saying it was offensive to them and wanted me to change it.
What a h**o.


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I wouldn’t mind if you changed it.

You could take her shirt off.>:)
 

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Believe it or not someone PM’d me saying it was offensive to them and wanted me to change it.
What a h**o.


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Damn, the snowflakes have made it here
 

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I'm sorry, I didn't hear your question. I was distracted by your wonderful Avitar.


Believe it or not someone PM’d me saying it was offensive to them and wanted me to change it.
What a h**o.


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That's because he likes pen-is instead.
 

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A friend told me that he unbolted the rear pipe on the CAT, pushed the pipe aside and reamed all the stuff out of the cat with a 1" spade bit on a 2' extension and a prybar and rebolted everything back together, took about 30 minutes he said. My friend said his truck ran better but had a more pronounced diesel odor. My friend is happy with the fuel economy and better performance....
 

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Discussion Starter · #14 ·
A friend told me that he unbolted the rear pipe on the CAT, pushed the pipe aside and reamed all the stuff out of the cat with a 1" spade bit on a 2' extension and a prybar and rebolted everything back together, took about 30 minutes he said. My friend said his truck ran better but had a more pronounced diesel odor. My friend is happy with the fuel economy and better performance....


I’ve got a spare cat that I’ll do that to, the injector got broken when it was shipped to me. I’ll need to cut mine out and put this one in its place. You know, just in case I have to put it all back together at one time.


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I wouldn’t mind if you changed it.

You could take her shirt off.>:)
Yup, we're all pervs around here. In my mind, boobs are boobs and guys are guys and guys like boobs. It's just that simple. We just want more.

A friend told me that he unbolted the rear pipe on the CAT, pushed the pipe aside and reamed all the stuff out of the cat with a 1" spade bit on a 2' extension and a prybar and rebolted everything back together, took about 30 minutes he said. My friend said his truck ran better but had a more pronounced diesel odor. My friend is happy with the fuel economy and better performance....
And I bet that friend watches you shave every morning from the other side of the mirror.

Now to the subject at hand. Your mechanic needs to do some research on your truck. The order of things in the exhaust, from the engine to the tail pipe, are:

1st is the NOx sensor.

2nd is the injector that adds fuel to the exhaust for processing in the oxidizing catalytic converter.

3rd is the first of 4 EGT sensors.

4th is the first of 2 catalytic converters. This is the one that we all think of as the catalytic converter. This cat oxidizes (burns) hydrocarbons left from incomplete combustion (of which there aren't many) and those injected by the injector just mentioned (which can be a lot at times) and creates heat for the use of the next converter and the diesel particulate filter. Note that this first cat is exposed to the full stream of soot. It always was. It never had any protection from the factory. The fuel injected ahead of it does not ignite until this cat sets it off. Lacking this injected fuel the cat would work just like it did for many years prior to DPF

5th is the second EGT sensor which is used to see if the cat is working since if the cat is working the exhaust will get hotter than it was when it passed the first EGT sensor.

6th is the DEF injector. The urea in the DEF, left to its own devices, would destroy the next (reducing) converter at low temps. To protect the catalytic converter the computer manages the exhaust temperature to keep it above 490F. When the exhaust is cooler the DEF is not injected.

7th is the SCR or selective catalyst reduction which is a verb that is used as a noun. Hey, they are engineers, not writers. When it is above 490F this catalyst uses DEF to react with NOx in the exhaust to make water, CO2 and N2 (that's nitrogen). The SCR shares a housing with the DPF and 3 other things.

Between the SCR and the DPF is a fitting for the DPF differential pressure sensor. There is another fitting just behind the DPF, in the exhaust pipe, where the other side of the differential pressure sensor connects. This sensor detects how much pressure it is taking to push exhaust through the filter. When the pressure differential becomes too great the system enters regeneration. I won't count the differential pressure sensor since it is not exactly in the exhaust pipe.

Also between the SCR and DPF is the third EGT sensor (8th). Just behind that is the second NOx sensor (9th).

10th is the diesel particulate filter. It is here because when the 9th injector is wasting fuel into the exhaust this will be the hottest part of the exhaust so that the soot it has collected will be burnt off.

11th is the last EGT sensor which tells the ECM when the soot is done burning off since soot is a fuel and when it burns the exhaust gets even hotter but when it is gone the exhaust is a little cooler.

12th is the exhaust cooler. That is that funny looking thing at the end of the tail pipe that looks like it is there to just make the pipe look bigger but in fact is there to mix enough cooler air with the exhaust that it won't ignite everything within 50 feet of the truck. The temperature of the exhaust coming out of the DPF can exceed 1000F. More than hot enough to ignite the tires of the care stopped next to you in traffic, not to mention the skirt of that cute girl standing on the curb. And while removing her skirt would fit right in with the kind of guys we are, I don't think we want to use a blow torch to do it.

So, the point is, leaving the oxidizing cat in place while removing the reducing cat, DPF, 9th injector and all of the other stuff doesn't mean that the cat will plug up with soot. Go ahead and remove it if you like but it probably isn't causing any problems in the first place. Also, since DEF is injected downstream of the oxidizing CAT it can have no effect on what happens there, nor can the lack of DEF affect the oxidizing cat.
 

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Discussion Starter · #16 ·
I'm not the only one going 80mph on this stretch of freeway, the speeds reach 75 to 85mph, this is the norm - single drivers in the carpool lanes, semi trucks in the #2 lane without really any police presence. But as long as I have been driving this stretch for the last year there have been no accidents on my way into work, but this is going the opposite way of traffic. The side that is backed up is usually the side that seems to have all the accidents.
 

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A friend told me that he unbolted the rear pipe on the CAT, pushed the pipe aside and reamed all the stuff out of the cat with a 1" spade bit on a 2' extension and a prybar and rebolted everything back together, took about 30 minutes he said. My friend said his truck ran better but had a more pronounced diesel odor. My friend is happy with the fuel economy and better performance....
gonna be honest with you, that sounds like a terrible idea. You are destroying an expensive part that does not actually cause any significant reduction in flow. There should be nearly 0 noticeable change in economy power or performance from this mod. Your truck will still not pass IM like this, so its a visual thing only. Really no point IMO. Leave it on if you dont want the smell, or take it off if you dont want it there. Destroying it is just lighting money on fire if you ever want / need to return to stock.


Yup, we're all pervs around here. In my mind, boobs are boobs and guys are guys and guys like boobs. It's just that simple. We just want more.



And I bet that friend watches you shave every morning from the other side of the mirror.

Now to the subject at hand. Your mechanic needs to do some research on your truck. The order of things in the exhaust, from the engine to the tail pipe, are:

1st is the NOx sensor.

2nd is the injector that adds fuel to the exhaust for processing in the oxidizing catalytic converter.

3rd is the first of 4 EGT sensors.

4th is the first of 2 catalytic converters. This is the one that we all think of as the catalytic converter. This cat oxidizes (burns) hydrocarbons left from incomplete combustion (of which there aren't many) and those injected by the injector just mentioned (which can be a lot at times) and creates heat for the use of the next converter and the diesel particulate filter. Note that this first cat is exposed to the full stream of soot. It always was. It never had any protection from the factory. The fuel injected ahead of it does not ignite until this cat sets it off. Lacking this injected fuel the cat would work just like it did for many years prior to DPF

5th is the second EGT sensor which is used to see if the cat is working since if the cat is working the exhaust will get hotter than it was when it passed the first EGT sensor.

6th is the DEF injector. The urea in the DEF, left to its own devices, would destroy the next (reducing) converter at low temps. To protect the catalytic converter the computer manages the exhaust temperature to keep it above 490F. When the exhaust is cooler the DEF is not injected.

7th is the SCR or selective catalyst reduction which is a verb that is used as a noun. Hey, they are engineers, not writers. When it is above 490F this catalyst uses DEF to react with NOx in the exhaust to make water, CO2 and N2 (that's nitrogen). The SCR shares a housing with the DPF and 3 other things.

Between the SCR and the DPF is a fitting for the DPF differential pressure sensor. There is another fitting just behind the DPF, in the exhaust pipe, where the other side of the differential pressure sensor connects. This sensor detects how much pressure it is taking to push exhaust through the filter. When the pressure differential becomes too great the system enters regeneration. I won't count the differential pressure sensor since it is not exactly in the exhaust pipe.

Also between the SCR and DPF is the third EGT sensor (8th). Just behind that is the second NOx sensor (9th).

10th is the diesel particulate filter. It is here because when the 9th injector is wasting fuel into the exhaust this will be the hottest part of the exhaust so that the soot it has collected will be burnt off.

11th is the last EGT sensor which tells the ECM when the soot is done burning off since soot is a fuel and when it burns the exhaust gets even hotter but when it is gone the exhaust is a little cooler.

12th is the exhaust cooler. That is that funny looking thing at the end of the tail pipe that looks like it is there to just make the pipe look bigger but in fact is there to mix enough cooler air with the exhaust that it won't ignite everything within 50 feet of the truck. The temperature of the exhaust coming out of the DPF can exceed 1000F. More than hot enough to ignite the tires of the care stopped next to you in traffic, not to mention the skirt of that cute girl standing on the curb. And while removing her skirt would fit right in with the kind of guys we are, I don't think we want to use a blow torch to do it.

So, the point is, leaving the oxidizing cat in place while removing the reducing cat, DPF, 9th injector and all of the other stuff doesn't mean that the cat will plug up with soot. Go ahead and remove it if you like but it probably isn't causing any problems in the first place. Also, since DEF is injected downstream of the oxidizing CAT it can have no effect on what happens there, nor can the lack of DEF affect the oxidizing cat.


As always, a well written and detailed explanation, thank you.
 

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gonna be honest with you, that sounds like a terrible idea. You are destroying an expensive part that does not actually cause any significant reduction in flow. There should be nearly 0 noticeable change in economy power or performance from this mod. Your truck will still not pass IM like this, so its a visual thing only. Really no point IMO. Leave it on if you dont want the smell, or take it off if you dont want it there. Destroying it is just lighting money on fire if you ever want / need to return to stock.

My friend is pretty smart, he has a spare CAT taken off an 18K mile truck...just in case. Been sitting in his shop with plugs in both ends for about 8 years now. Never know when one of those is gonna fail!
 

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The Autobahn has generally no or very high speed limits for most of its stretches and has an annual fatality rating of 2.7 deaths per 1,000,000,000 KM traveled.

The United states highways average an annual fatality rating of 19.6 fatalities per 1,000,000,000 KM traveled.

From this data you could either conclude that speed limits are 7.26 times more likely to kill you then no speed limits, or more reasonably, that US drivers are terrible at driving, either way, higher speeds are not really the problem.
 

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gonna be honest with you, that sounds like a terrible idea. You are destroying an expensive part that does not actually cause any significant reduction in flow. There should be nearly 0 noticeable change in economy power or performance from this mod. Your truck will still not pass IM like this, so its a visual thing only. Really no point IMO. Leave it on if you dont want the smell, or take it off if you dont want it there. Destroying it is just lighting money on fire if you ever want / need to return to stock.

My friend is pretty smart, he has a spare CAT taken off an 18K mile truck...just in case. Been sitting in his shop with plugs in both ends for about 8 years now. Never know when one of those is gonna fail!

You do you boo boo
 
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