Smelly delete and an aftermarket CAT?

[emus528]

Preamble: Please limit responses to the subject; yes, deleting is technically illegal, immoral and fattening. If you want to preach about that, start your own thread.

I have decades of experience driving diesels going back to the GM 5.7 diesel. I have owned a 1991 Golf 1.6 TD and currently still drive an ALH engine Syncro van. I know the glorious smells of these diesel vehicles and really don’t mind it at all.

I recently deleted my 2013 Golf CJAA (deleted DPF, deleted factory secondary CAT and completely deleted and removed EGR. Flashzilla Stage 2). I have the Flowdirect downpipe and “high flow” cat option that they offer. The deleted CR engine exhaust smells many times worse than any of my previous dirty diesels. Note that I have no leaks-no smell inside the car with windows closed. Unfortunately, I cannot drive with the windows or sunroof open and I pity pedestrians and cyclists in my general area. There is no smoke. Just smelly.

My experience is similar to many who opined in this thread:
https://forums.tdiclub.com/index.php?threads/how-bad-is-the-smell-after-dpf-delete.508219/page-3

Frankly, I don’t think the “high flow” cat option from Flowdirect is doing anything.
Has anyone added another aftermarket CAT to their deleted systems and can you report on how well it reduced the smell?

 

[Garrison]

Interesting - I don't find the smell all that bad; I did a high-flow cat as well. If you kept your secondary cat you could always add that into the mix downstream.

 

[oilhammer]

Curious as to what specific component, from this diagram, that one would label as a "secondary cat"?

 

[emus528]

I have all of that deleted... I should have stated secondary CATS.
NOx and H2S both deleted as well.
I still have them; wondering which one, if I did reinstall, would make a meaningful difference vs. an aftermarket diesel specific CAT

 

[oilhammer]

I suspect that none of these aftermarket catalysts are actually made from anything that is specifically made for a diesel. Reason I say this is, even on the VE and PD cars, the aftermarket catalysts simply don't work like the OEMs do. So I am betting that on the CR, the same thing applies.

Diesels cannot use a traditional 3-way catalyst like modern gasoline engines can. And shoving one on won't do much of anything I think.

From the factory, the CR cars have a bunch of bits, but I don't know if any would be an analog to the one component that the VE and PDs did, however I suspect that if there is one it would be the DOC (Diesel Oxidation Catalytic Converter), which is contained inside the upper housing of the DPF assembly. So, there is no easy way to keep that, and only that, and delete the rest. And without a functional DPF, everything downstream would be killed in short order anyway, as the NOx storage and H2S catalysts are only intended to work with a clean soot-free exhaust. And when the DPF is functioning properly, they do get just that. The post-DPF exhaust is squeaky clean.

This is the INSIDE of a CKRA's downpipe, which is similar to the CJAA, just has a more straight shot so you can actually see up into it:

You'll never get any aftermarket anything that clean. I do wish someone with a higher pay grade than me would chime in with what specifically the VE and PD cars used as OEM, and how one could employ that same type of component to deleted CRs, because I do think it would knock the smell down quite a bit. No reason a CR engine, with its far more sophisticated combustion control, should not at least be able to be as low smell as something with warmed over 1970s technology.

I can run my 625k mile ALH, with an OEM BEW downpipe/catalyst, in the shop and you'd barely notice. I pull a deleted CJAA through here and you smell it for a half hour afterwards.

 

[Garrison]

Curious as to what specific component, from this diagram, that one would label as a "secondary cat"?

The one on the right "H2S Catalytic Converter"

 

[saboteur]

Has anyone tried a supposedly Euro 5 compliant diesel catalytic converter like this?

https://kat-eko.com/en/universal-catalysts/230-2611-universal-catalytic-converter-20-30l-diesel-awg-5904347502782.html#/58-euro_standard-euro_5/62-capacity_cpsi-300

 

[McGuirk]

I run the rawtek cat they offered. Car doesn't smell that much. I can drive with the windows down no problem, especially once the car is warmed up. I do also run a ccv filter (provent 200 by MANN) that probably helps quite a bit. It does a great job of catching the oil out of the ccv gasses.

 

[oilhammer]

The one on the right "H2S Catalytic Converter"

Then that would presume the smell is coming from an excess of hydrogen sulfides, and nothing else, and that the specific elements inside of it can continue to work in light of nothing being cleaned up ahead of time.

As it turns out, I just untooefed an epic Fail with a catastrophic Crimes Against Mechanicals that somewhat relates to this topic.

Some moron removed a DPF from a CJAA, cut it open and gutted it, installed it back on the car that was otherwise whole and completely unmodified in any way. It made it about 5000 miles before it stopped up the rest of the exhaust AND took out the turbocharger.

So again, the various components work in concert, and I don't think it wise to pick any one part out to work by itself properly... aside from the DOC as I mentioned earlier, which wouldn't really be easily done given its location.

 

[emus528]

That would have a rotten-egg smell, which i don't recall anyone complaining about.

Agree, and it is NOT a sulphurous odor.

Has anyone tried a supposedly Euro 5 compliant diesel catalytic converter like this?

https://kat-eko.com/en/universal-catalysts/230-2611-universal-catalytic-converter-20-30l-diesel-awg-5904347502782.html#/58-euro_standard-euro_5/62-capacity_cpsi-300

I have ordered a different "diesel specific" CAT and will give it try... We'll see.

...I do also run a ccv filter (provent 200 by MANN) that probably helps quite a bit. It does a great job of catching the oil out of the ccv gasses.

Did you run a before and after and notice if the CCV changed anything?

 

[Garrison]

Then that would presume the smell is coming from an excess of hydrogen sulfides, and nothing else, and that the specific elements inside of it can continue to work in light of nothing being cleaned up ahead of time.

That's a good point - OP said he had a a cat in the downstream, so naturally assumed adding a second one would reduce the smell further. I don't have the H2S cat -but no egg smell at all; does any modern diesel have that smell? I don't think I've ever noticed it before

 

[emus528]

We'll see if an additional CAT will clean it up at all. Remember, I don't mind a bit of Prius repellent. My ALH has bigger injectors, Stage 2, etc and emits a tolerable perfume.
The Golf exhaust stinks

 

[borninabus]

I have ordered a different "diesel specific" CAT and will give it try... We'll see.

which one did you order? the one listed previously is a little pricey, euro 5 and shipping from england. i'm sitting on a darkside pipe, but haven't installed yet due to fear of the smell.

 

[smelly621]

I have this cat on my CJAA: https://www.idparts.com/catalytic-converter-94109-75330-p-4969.html#product_tabs

Once it's good and hot there is really minimal smell, but for short errands and at start up it stinks way more than my 5.9 cummins which just has the oem cat (no dpf or def). If that ID parts cat eventually clogs on me I'm going to try and fit a diesel truck cat from the same era under there.

 

[Speedmaster_102]

I do also run a ccv filter (provent 200 by MANN) that probably helps quite a bit. It does a great job of catching the oil out of the ccv gasses.

Can you provide pics of that setup? That's a first I've heard of it.

 

[McGuirk]

Can you provide pics of that setup? That's a first I've heard of it.

Oil leak near firewall??

Bought a provent 200 ccv filter. I have high hopes that this will stop 90% of the oil I'm seeing. I purchased the adapter that attaches directly to the valve cover off ecs. I'll try to post results after some time running with it...

forums.tdiclub.com

 

[emus528]

which one did you order? the one listed previously is a little pricey, euro 5 and shipping from england. i'm sitting on a darkside pipe, but haven't installed yet due to fear of the smell.

This

 

[Speedmaster_102]

Oil leak near firewall??

Bought a provent 200 ccv filter. I have high hopes that this will stop 90% of the oil I'm seeing. I purchased the adapter that attaches directly to the valve cover off ecs. I'll try to post results after some time running with it...

forums.tdiclub.com

That's awesome! Where did you order it from? Does it come with the installation instructions?

 

[borninabus]

so i cross referenced the part number for the 2.5" cat linked on idparts to the magnaflow site and it does not reference anything about being a "diesel" cat. which raises the question of what is a "diesel" cat? is it different from a gasser? and better yet: where to get one?
if you shop by vehicle (2006 jetta) on idparts or by any TDI on magnaflow there are no options given for any cat....

 

[Beewi]

OP, I'm curious about what exactly you find offensive about the exhaust on this car vs your old diesels. It's not a sulfide-eggy smell, but is it the sort of sharp smell that sort of makes you crinkle your nose and feel like you have a tickle in your throat that makes you feel like coughing? If you hold a sheet of white paper up to your exhaust while someone starts the car, do you get a yellowish color coming out of the tailpipe?

I ask because it almost sounds like your car could be outputting more NOX than it ordinarily should. And because I recently was behind a deleted pickup on the highway belching yellow exhaust for almost a mile before whatever tune he had changed the fuel-air ratio.

Also, my understanding of the high flow cats is that they perform the same chemistry as the stock cats on the mid pipe, but are wider, with a less restrictive lattice to accommodate the soot they're going to see in a filter-free car. They aren't DOCs, so they won't finish off unburnt fuel, but they should knock down at least the hydrogen sulfide.

 

[emus528]

Beewi,
There are no visible yellowish color, visible particulates or smoke on start-up. And yes, it is not a rotten egg smell.

 

[Tuheeden]

I have used the Flowdirekt CAT and it worked well however what really made the difference was what engine oil used. Run Mobile 1 ESP you could barely smell it except during warm up, us Amsoil DHD signature series and it smells like my tractor when cold but gets somewhat better once hot.

 

[McGuirk]

That's awesome! Where did you order it from? Does it come with the installation instructions?

Here is the filter

MANN ProVent 200 CCV Filter

GENUINE MANN-FILTER Provent 200. Installing a Provent 200 into your crank case ventilation system prevents oil vapors from making it into your engine's intake. Oil vapors in the intake can mi...

www.idparts.com

Here is the special adapter to hook up to our CCV system. You need 2 of these.

https://www.ecstuning.com/b-ecs-parts/pcv-intake-adapter/006235ecs02~a/

After that you need the hoses, 10AN fittings, and clamps to connect it all. I added a drain tube with a ball valve down to my driver side fog light for quick draining.

 

[p.e.fletcher]

ProVents are great and I have them installed on two cars - a CJAA Golf and a CKRA Passat both big turbo straight piped.

They keep the intake tracts sparkly clean but they both still stink pretty bad when idling…

The AN stuff looks really nice @McGuirk! I might have to upgrade my fittings, but for anyone else interested you can get away with 1” heater hose or 1” pvc hose because the stock ccv connections and ProVent connections are all 1” to begin with. On my Passat, I put mesh over the heater hose with heat shrink ends came out looking pretty nice. PVC hose is nice on the other hand because you can see what it’s doing, so I did that on my Golf.

 

[Speedmaster_102]

ProVents are great and I have them installed on two cars - a CJAA Golf and a CKRA Passat both big turbo straight piped.

They keep the intake tracts sparkly clean but they both still stink pretty bad when idling…

The AN stuff looks really nice @McGuirk! I might have to upgrade my fittings, but for anyone else interested you can get away with 1” heater hose or 1” pvc hose because the stock ccv connections and ProVent connections are all 1” to begin with. On my Passat, I put mesh over the heater hose with heat shrink ends came out looking pretty nice. PVC hose is nice on the other hand because you can see what it’s doing, so I did that on my Golf.

Are you able to provide pics of your set-up?

 

[rewease]

It's not a sulfide-eggy smell, but is it the sort of sharp smell that sort of makes you crinkle your nose and feel like you have a tickle in your throat that makes you feel like coughing?

That's NOx IMO. Cars with NOx cats fitted run higher levels of it for engine efficiency as it is taken care of by the cat anyway.

 

[p.e.fletcher]

Are you able to provide pics of your set-up?

Sure, here’s my CJAA Golf. Plenum cover is off because I started a new coilover install today so just ignore that.

For the ProVent, I cut and bent a bracket from steel plate and used top driver side headlight bolts for mount point on this one. This car has a GTB2260 with a pie-cut intake I made for it with the CCV pipe on the bottom side just because I thought it worked well that way with everything laid out. Obviously you’ll just have to get a bit creative with your mount and routing.

I used this generic 90 at the valve cover and pulled the plastic 45 out of the stock ccv hose and used it to join to 1” pvc:

https://www.amazon.com/AUTOHAUX-Degrees-Silicone-Coolant-Universal/dp/B0D2P1VDB4

I’ll get pictures of the Passat tomorrow since it’s dark here now and that one is outside. It also has a GTB2260 but it’s using a frankensteined CR170 intake pipe so maybe closer to stock layout.

IMG_3849.jpeg

• p.e.fletcher
• Mar 13, 2025

IMG_3850.jpeg

• p.e.fletcher
• Mar 13, 2025

IMG_3851.jpeg

• p.e.fletcher
• Mar 13, 2025

 

[Speedmaster_102]

That's one clean diesel!

 

[borninabus]

Catalytic Converter VW Golf V 2.0 TDI 16v (1K1)

All car parts that you can buy here with 'Add to Cart' are available in our warehouse in Reinfeld (between Hamburg and Lübeck) and will be sent to you by order & payment by 14:00h on the same working day. Includes: - 1x Catalytic Converter VW Golf V 2.0 TDI 16v (1K1) brand new and packed...

www.dpf-catalysts24.com

i'm working on getting this piece shipped from germany as i cannot find anything new in the states for reasonable money.

wondering how @emus528 is doing?

 

[ApproachMedium]

This thread is very interesting as I have a straight piped 2010 golf CJAA ive been working on to put up for sale. It STINKS. and its obnoxiously loud. Id love to quiet it down but helping the smell would be nice.

Ive even had nightmares about un-deleting it. Crazy here we are talking about how to clean up a deleted car. The process thats been come up with for parts to work with each other to do just that is of course very interesting.