As the says. What does the SCT tuner do?
1)Does it shut down all of the EGT sensors?
2)I've read that you no longer need the throttle body. Is this true?
3)Do I NEED to unplug the EGR and all the exhaust plugs? Id like to keep it looking 100% factory and ALL the original plugs plugged into their respective sensors, pumps, and valves.

 

You have to have the delete tunes in order to delete things. The factory SCT canned tunes won't delete. But to answer you questions (at least with PIP tunes), the SCT will:

1 Yes
2 True
3 There are parts of the EGR that need to be unplugged, but they are easy to get to. But you will want to get rid of the DPF though. And doing so you will have to undo all the EGT sensors.

 

Ok. Thank you.
I'd like to keep the throttle body as an anti runaway device.
I have the PIP tune and I plan on hollowing out the "spaceship" to keep it looking stock. It's over 75% plugged anyway.
So in leaving the DPF/SCR in place but hollow, I'd like to keep everything plugged in. Will that not work?

 

I Wouldn't see why keeping it plugged in would be a problem. It would be interesting to see if the delete made it so you couldn't get temp values from them.

Curious how that hollowing out goes...

 

Probably something like this

 

LOL... A long and large drill bit might go a long way. Especially if attached to a hammer drill.

 

If you have the talent, tools and patience to hollow out a 7' long multi-chamber assembly, leaving things plugged into it won't hurt anything, once the delete tunes are functioning. The computer disregards any readings coming from sensors related to emissions. It also disables the throttle body, so leaving it in to prevent a runaway won't help. Once deleted, the guys writing the tunes recommend unplugging the throttle body so that it doesn't try to come open with stray voltage and allow flow across it. All of that is a lot of trouble to go through to prevent the appearance of being deleted, but all someone has to do to figure out that there's a problem with the emissions on that truck is to stick the tip of their finger into the tail pipe. When it comes out black, they will know you have at least a cracked DPF.

 

I agree with all you said, except the egr butterfly valve is normally open, even when full emissions are present. So stray voltage will not 'open it'.

The egr butterfly throttle valve only closes partially/fully when the pcm decides the engine needs to breath in more egr, so then the egr butterfly throttles down the clean pressurized air from the intercooler, allowing more egr to flow into the intake manifold.

The reason to unplug the egr throttle valve is only to stop the calibration cycling that occurs on every start up. If something were to happen to hang the valve up in a partially closed position during this now unneeded calibration cycle, this could cause a major performance problem. Its not needed and just unplugging the valve will take that possible problem off the table. That being said, many run deleted and never unplug anything and run fine for hundreds of thousands of miles.

When the ign key is turned to on/start the egr throttle butterfly opens and closes to let the pcm know what the positions of fully closed/open are. Same as most gas efi engines calibrate their throttle body on every start up. This takes a fraction of a second before the engine actually starts up.

Tuners don't want to change the complicated, needed, start up protocol, that includes the now unneeded cycling of the egr throttle valve, so thats why the unplug recommendation exists...

So if you want to leave it still plugged in, shouldn't be a problem, they are electronically deleted and the truck will run fine. Although you will be going against the tuner recommendations of unplugging them because of the rare case it hangs up when doing its start up unneeded cycle calibration that can't be easily deleted from the pcm start up procedure...

Many that gut the dpf, do so by cutting open a large 'window to gut it, on the top of the dpf that is not visible once its installed back on the truck.

jmo

 

You are absolutely correct and it makes sense. I didn't fully recall the discussions I had with my tuner about that a year ago, as I was writing the response at the wee hours of the morning while doing my best to stay awake on my first night shift back.
That being said, I still don't believe that keeping it around and connected for the purpose of preventing a runaway will do any good, as the delete tune would have to be specifically written to address the condition IMHO.
With regard to soot in the stock tailpipe, my truck developed a crack in the DPF less than a year after I purchased it. Running completely stock, it would blow a small amount of visible soot from a stop or rolling start, and left the tell-tale black film inside the polished tips. That was with enough of the function of the DPF still present to prevent a CEL, even though it was cracked.

 

So what would happen if the sensor on the DPF never changed values and always indicated that the filter was 35%?

 

If you were not running tunes, the computer would regen based on miles alone after a certain period (around 500 miles on mine previously). I would be willing to bet that the computer would set a CEL or two as well. Of course, you would have to provide a means of not filling the DPF between miles based regens as well.

 

Many thanks to all your input guys.
The deed is done. I've hollowed a few catalytic converters in my day and the DPF is like cement compared to a "cat". Also you need to go at it from both ends because of the DEF mixing chamber in the middle.

I'm very mechanically inclined and I like to know just what is happening with my truck inside an aftermarket tune. They don't give you reasons why to unplug things, they just say to do it. That's not enough for me.

I'm also installing an EGT sensor and guage in the exhaust manifold where the EGR tube is connected. This will be as inconspicuous as possible too. I'll post a pic when it's done.

 

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Steve, love to see your posts on the EGT install. I'd like to do that as well. I got to this thread too late. I ran my SCT with delete tunes with my EGR in and nothing unplugged for about a year before I finally had an EGRemoval surgery. As to the rocket ship, I would have suggested to just simply remove it and replace it with a straight pipe. That way you can always put it back in if the need should arise, as I have done.

Sounds like you got that straight pipe through another method.