[melonbread]

I thought after the tune and DPF removal the car was bullet proof but i'm guessing it's not until you remove SCR by installing exhaust system?

[GaryE30]

Inherently "something" will fail more times than "nothing".

In other words the electrical / mechanical / chemical components of the SCR / DEF system are more prone to failure than a straight through pipe.

Everything has a lifecycle and its only a matter of time before something fails and will need to be replaced.

[rulonger]

Downpipe will remove the DPF which in turn may cause clogging of the SCR. Several threads have pictures of this phenomenon. Even if you code out the urea spray, the cat will become clogged with time.

I believe that the natural progression, after the downpipe install, would lead you to either gut the SCR or remove it entirely with an exhaust modification.

[melonbread]

Originally Posted by rulonger

Downpipe will remove the DPF which in turn may cause clogging of the SCR. Several threads have pictures of this phenomenon. Even if you code out the urea spray, the cat will become clogged with time.

I believe that the natural progression, after the downpipe install, would lead you to either gut the SCR or remove it entirely with an exhaust modification.

thanks rulonger, has anyone gutted out the scr? i'm assuming you'll need some custom fabrication to do this? and if gutting out the scr, mind as well get rid of urea tank as well?

[GaryE30]

Originally Posted by melonbread

thanks rulonger, has anyone gutted out the scr? i'm assuming you'll need some custom fabrication to do this? and if gutting out the scr, mind as well get rid of urea tank as well?

Yes, people have gutted the SCR. It requires you to cut it open (abrasive cutoff wheel / angle grinder / etc.) and remove the internals, then have it welded closed.

No point in keeping the urea tank after you gut the SCR. Just dead weight. Only reason to keep it is to save yourself time from having to reinstall it if you decide to go back to stock and put a new SCR / factory exhaust back in the car.

[335ddd]

Originally Posted by GaryE30

Yes, people have gutted the SCR. It requires you to cut it open (abrasive cutoff wheel / angle grinder / etc.) and remove the internals, then have it welded closed.

No point in keeping the urea tank after you gut the SCR. Just dead weight. Only reason to keep it is to save yourself time from having to reinstall it if you decide to go back to stock and put a new SCR / factory exhaust back in the car.

with DPF / SCR gone, is the tuner able to code readiness monitors for inspection purposes for folks living in areas like NY where yearly inspection is a must. reinstalling every year does not sound like fun just to pass the emissions.

[GaryE30]

Originally Posted by 335ddd

with DPF / SCR gone, is the tuner able to code readiness monitors for inspection purposes for folks living in areas like NY where yearly inspection is a must. reinstalling every year does not sound like fun just to pass the emissions.

Ah, well then keep it in there. I'm in a state that doesn't require emissions checks. Mine is coming out.

[eric-satx]

Thank you for asking this question. After reading the relevant threads over and over I was coming to the same conclusion. If I understand correctly, the straight exhaust will rid you of the SCR clogging issue but introduce the potential for overboosting -- and more noticeable sound and smell.
It looks like the "trailblazers" are discussing options in: http://www.e90post.com/forums/showthread.php?t=1009945
Please, someone correct me if a full EGR/DPF/SCR solution already has been fully discovered.

[Mrdeezy]

Yeah, over boost or boost creep as they used to call it. Is compensated for by the tune. It's pretty much an all or nothing proposal.

Can anyone verify wether any tune will run all of the readiness monitors?

[Yozh]

Tune will not compensate for the overboost. You have to either run an external wastegate or bore out your stock one when you drop the DPF.

[BB_cuda]

+1 on tune not removing overboost. Go look at wastegate thread.

[briansjacobs]

thankfully I was informed I needed to do this ahead of time, we ported the wastegate when we deleted the DPF. took about 2 hours of very slow meticulous drilling.

[Persian Whisperjet]

Jarek did Phase I for me -- he said if I was not thrashing it too mercilessly I should not worry about overboost. Does that sound right?

[eric-satx]

Yozh,
Reading some older threads, looks like you ran/run with a gutted DPF/SCR (but retained the DOC). What was the verdict? I read on the UK forum that the gutted DPFs created a "plenum box" effect and boost could not be controlled -- but they did not state whether or not the DOC was left in. Also, I couldn't determine whether or not you ported your wastegate?

[Yozh]

I'm not sure about the plenum effect. TDIwyze can comment as he ran like that too. My DOC is in place and it's nice for controlling smell. My wastewate is not ported yet. I go easy on it, if I drive hard then I see 40psi spikes. It will be a third time for me removing the DPF and all the related engine mount etc. such a pain. Did it on my back the first time. So waiting to get access to a lift after my machine shop guy finishes his supercharged Chevelle.

[TDIwyse]

Originally Posted by Yozh

I'm not sure about the plenum effect. TDIwyze can comment as he ran like that too. My DOC is in place and it's nice for controlling smell. My wastewate is not ported yet. I go easy on it, if I drive hard then I see 40psi spikes. It will be a third time for me removing the DPF and all the related engine mount etc. such a pain. Did it on my back the first time. So waiting to get access to a lift after my machine shop guy finishes his supercharged Chevelle.

On your back even. Ouch.

The methods I was using to monitor boost when running the gutted DPF with the DOC in place did not capture the real boost #'s (standard Torque MAF based approach and the Bavarian Technic software), so I don't have accurate numbers on that. Sorry.