how did you gut your catalytic converter?

[unorganizedplan]

hey all -

during my endeavors to correct limp mode and low power issues . . . i think i clogged my catalytic converter. long story short, i tried cleaning the turbo vanes the lazy way . . . with oven cleaner. after all that and a couple other limp mode fixes the car is now quite spirited, much more than before but only boosts to about 9psi max, all conditions, and eventually throws P0299 underboost code.

i am thinking the oven cleaner soak (healthy doses, and overnight sit) may have clogged my catalytic converter.

for those that have gutted your catalytic converter it, how did you do it?

the only option i can see without cutting and welding, is to ram a long metal bar from the straight end (rear) and break up the innards until I can see through it, or the bar passes through.

i have seen many threads about gutting the catalytic converter, but very limited info about how to actually accomplish it!

any and all help is appreciated.

thank you,
jason

 

[unorganizedplan]

also, to further my troubleshooting (before I gut it) i will unbolt the downpipe from the turbo and drive it like that to see if there is any noticeable difference. if there is a difference then i think gutting is in order. if no noticeable difference, then i will bolt back up and move on.

 

[oilhammer]

I have never once seen an ALH with a clogged up catalyst. Even those that have literally hundreds of thousands of miles on them with mild power mods.

I think your boost loss issue lies somewhere else, perhaps a charge air leak somewhere.

 

[Dh4276]

I thought about doing the rod thing on mine, found it much easier to take $35 to a muffler shop and have the weld in a straight pipe!


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[vandermic07]

I second OH on leak and check for splits in Vac tube. Mine was split going to EGR and caused the same code. Trimmed the end of the tube and reinstalled. no issues since.

 

[nayr]

If your turbo is not glowing red hot after a drive, its not your cat..

 

[unorganizedplan]

I have never once seen an ALH with a clogged up catalyst. Even those that have literally hundreds of thousands of miles on them with mild power mods.



I think your boost loss issue lies somewhere else, perhaps a charge air leak somewhere.

This car was new to me at 425,000Km. It has 429,000Km now.
Most recent previous owner was my father, who likely feathered the throttle for all his driving.

The car used to boost higher, but no longer does after the oven cleaner soak. However, the turbo DOES seem less sluggish up to the 9-10 psi mark.

I have visually inspected the charge air tract, but have not leak tested with pressure. I have also listened for the whoosh/boost leak sounds while driving and have never heard a thing. I have heard the whooshing/leak sounds on other cars so I have an idea of what it would sound like. It's possible it is a lighter sound being drowned out by other noise.

I have a mityvac, and air compressors handy... What it your best advice for leak testing procedures? (I can build a simple device if necessary)

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[unorganizedplan]

I thought about doing the rod thing on mine, found it much easier to take $35 to a muffler shop and have the weld in a straight pipe!


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This is a consideration. However local labor/shop rates are usually at least $100/hr around here...

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[unorganizedplan]

If your turbo is not glowing red hot after a drive, its not your cat..

I will take a look after giving it a spirited drive. I am noticing a 'hot' smell fairly often when I shut down. Maybe it's the turbo heating as you suggest.

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[unorganizedplan]

I second OH on leak and check for splits in Vac tube. Mine was split going to EGR and caused the same code. Trimmed the end of the tube and reinstalled. no issues since.

All vacuum lines have already been replaced, and recently checked with mityvac.
The EGR cooler is long gone, vac lines rerouted accordingly. The EGR valve is still physically in place, but of course disabled.

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[Powder Hound]

I used my mityvac to check the actuator, ensuring it is holding vacuum, which it was. Made sure the lever moved correctly and rapidly.

Checked the N75 to see that it was supplying vacuum when it should by using my VCDS to run an output test on the N75. It also showed that it supplied sufficient vacuum, so the boost lag wasn't because the N75 wouldn't do its job.

Unbolted the charge air pipe at the lower end of the intercooler and used shop vac output to blow the intake tract to see if I could find a pressure leak anywhere. No leaks found.

Spent lots of time logging group 11 on my VCDS while driving then checking the log to see if the boost would keep up with the requested, which it would, eventually. The lag caused an underboost error code. Drove with anemic power, similar to limp mode but not quite as it didn't have regular power before.

Finally decided to change the fuel filter. I had noticed that the air bubble in the input fuel line got much larger when the go pedal was pushed, and finally (delayed cognizance) realized that what would cause it would be the fuel just isn't running through the filter in sufficient quantity to do the job of running the engine above idle. For me, this was the answer as it drives fine now.

HTH & Cheers,

PH

 

[Rrusse11]

Manifolds clean?

 

[leafs]

To do it on the car it's going to be a sh1t show. I cut mine off the car and went to Canadian tire and attached a sleeve. Even off the car it fought tooth and nail. Once you get it going though it starts coming out in chunks. Now I got that nice owl sound though even with the stock muffler... not overly obnoxious but still nice sounding. Car does stink a bit though lol.

 

[Nero Morg]

I dunno about y'all, but I put a 2.5in cat on, after running arond for a while cat less. Mostly for noise suppression, but smell suppression was a bonus.

 

[unorganizedplan]

To do it on the car it's going to be a sh1t show. I cut mine off the car and went to Canadian tire and attached a sleeve. Even off the car it fought tooth and nail. Once you get it going though it starts coming out in chunks. Now I got that nice owl sound though even with the stock muffler... not overly obnoxious but still nice sounding. Car does stink a bit though lol.

Ha, I wouldn't be doing this on the car!
I plan to remove and give it a shot.
What do you mean you attached a sleeve?

What method did you use to break the chunks out?

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[unorganizedplan]

Manifolds clean?

Nope.
I don't plan on keeping the car too long, so it's not at the top of my list.
Going to try less time consuming simple things first, saving manifold and port cleaning for last.
The next owner can invest their time into that!



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[unorganizedplan]

I dunno about y'all, but I put a 2.5in cat on, after running arond for a while cat less. Mostly for noise suppression, but smell suppression was a bonus.

It's pretty stinky right now as is, making me wonder if my cat is clogged or even fining proper.

I don't mind diesel exhaust smell (at least not if it's getting the proper amount of fuel)

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[unorganizedplan]

I used my mityvac to check the actuator, ensuring it is holding vacuum, which it was. Made sure the lever moved correctly and rapidly.

Checked the N75 to see that it was supplying vacuum when it should by using my VCDS to run an output test on the N75. It also showed that it supplied sufficient vacuum, so the boost lag wasn't because the N75 wouldn't do its job.

Unbolted the charge air pipe at the lower end of the intercooler and used shop vac output to blow the intake tract to see if I could find a pressure leak anywhere. No leaks found.

Spent lots of time logging group 11 on my VCDS while driving then checking the log to see if the boost would keep up with the requested, which it would, eventually. The lag caused an underboost error code. Drove with anemic power, similar to limp mode but not quite as it didn't have regular power before.

Finally decided to change the fuel filter. I had noticed that the air bubble in the input fuel line got much larger when the go pedal was pushed, and finally (delayed cognizance) realized that what would cause it would be the fuel just isn't running through the filter in sufficient quantity to do the job of running the engine above idle. For me, this was the answer as it drives fine now.

HTH & Cheers,

PH

Fuel filter is good, changed only a couple thousand Km ago.

I don't have VCDS (for MK4) to log or investigate anything. Not keeping the car for too long, so going to avoid buying VCDS.

I have a MityVac, and ask my checks have come up good so far.

I'll check the intercooler piping for leaks/oil accumulation while I'm under the car removing the cat.

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[leafs]

Ha, I wouldn't be doing this on the car!
I plan to remove and give it a shot.
What do you mean you attached a sleeve?

What method did you use to break the chunks out?

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This type of setup. Obviously not ideal but it works. To remove the honey comb it was a long rod with a big hammer and lots of hammering.

 

[vwdsmguy]

Uncloging

I measured the back pressure before the cat [years ago. can't remember the # value]. It was restricting power so I cut thru the outer shell and removed the first of 2 core sections [seperated by an air gap] and rewelded it back together. This 2 1/2" system runs like new now.

 

[unorganizedplan]

This type of setup. Obviously not ideal but it works. To remove the honey comb it was a long rod with a big hammer and lots of hammering.

I thought about this, but it's not lined up, plus the hangers are right near the boxy of the cat.

I think a long bar and small sledge will have to do for me, just punch away and let it come out little by little.

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[unorganizedplan]

I measured the back pressure before the cat [years ago. can't remember the # value]. It was restricting power so I cut thru the outer shell and removed the first of 2 core sections [seperated by an air gap] and rewelded it back together. This 2 1/2" system runs like new now.

That's good to know.
I think if I strike out with a large rod and sledge, I'll cut a window and core it out like that, then enlist the help of a local welder to seel it back up.

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[turbocharged798]

There is literally no reason to delete the cat on these cars. It helps the smell and have absolutely no draw backs. Well, maybe it reduces turbo sound if you like that but that's about it.

 

[Rrusse11]

When I replaced my entire exhaust, holes, I sold my cat for scrap. IIRC I got about a $120.
Stupid to break it up. Replace it with a piece of pipe.

 

[leafs]

When I replaced my entire exhaust, holes, I sold my cat for scrap. IIRC I got about a $120.
Stupid to break it up. Replace it with a piece of pipe.

I did it that way just in case the coppers tried to flex. Yeah chances are slim but I'd rather keep it appearing legal. Back then we also had emission testing where they visually inspected the exhaust. I passed gutted because they didn't sniff but checked the readiness monitors.

 

[unorganizedplan]

There is literally no reason to delete the cat on these cars. It helps the smell and have absolutely no draw backs. Well, maybe it reduces turbo sound if you like that but that's about it.

Wrong.
If it is badly clogged (my own fault) I think that is a good reason to lose it or gut it.
See my post #2 where I say if no noticeable different then I will leave it alone.

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[unorganizedplan]

When I replaced my entire exhaust, holes, I sold my cat for scrap. IIRC I got about a $120.
Stupid to break it up. Replace it with a piece of pipe.

Good to know.

Maybe I'll call a metal scrapper first. If they pay well enough, I'll just get a shop to do it right...

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[Rrusse11]

Locally there's a specialty scrapper who advertises for buying catalytic converters,
DPF filters etc. Enough platinum and some other rare metals to be worth while.
When I brought my cat in they checked to make sure it hadn't been reamed out.

It certainly helped to defray the cost of a complete new exhaust.

 

[leafs]

Wrong.
If it is badly clogged (my own fault) I think that is a good reason to lose it or gut it.
See my post #2 where I say if no noticeable different then I will leave it alone.

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less back pressure means the turbo breathes better and doesn't get as hot too.

 

[Nero Morg]

A functioning cat has barely any backpressure. This subject has been beaten to literal death. Here's some reading material.
http://forums.tdiclub.com/showthread.php?t=205022

https://forums.tdiclub.com/showthread.php?t=15210

If it's plugged, then do something about it, that's my 2 cents.