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vazbmw
vazbmw HalfDork
2/19/18 6:26 p.m.

It seems like most product descriptions don't include if the cat is 2-way or 3-way. Do any of you Grassers (I just made this up...maybe it's a thing LOL) know of a good 3" inlet and outlet/ oval cat that's 3-way?

I failed emissions like nobodies business on NOx. I need to scrub that exhaust hard. 

759NRNG
759NRNG SuperDork
2/19/18 6:39 p.m.

Sorry but not ever heard of such an animal (3waycat) ......a decent tune perhaps instead (on the BMWLS1)???

TenToeTurbo
TenToeTurbo Dork
2/19/18 6:45 p.m.

From the little bit of googling I just did, 2 way cats on gas engines fell out of favor in the early 80s due to their inability to scrub NOx. 

Gearheadotaku
Gearheadotaku UltimaDork
2/19/18 8:03 p.m.

what kind of car?

Try the Walker exhaust website. They have a list of good quality universal cats.

 

vazbmw
vazbmw HalfDork
2/19/18 8:08 p.m.

In reply to 759NRNG :

3 way cat does CO, HC and NOx. Two way only does CO and HC

It's for my Volvo 850, which has become a project car on it's on right...which was not the plan. It was supposed to be a stockish DD

vazbmw
vazbmw HalfDork
2/19/18 8:09 p.m.

In reply to Gearheadotaku :

Thanks. I did check them out, but could not find a 3". I will look more carefully

vazbmw
vazbmw HalfDork
2/19/18 8:11 p.m.

In reply to TenToeTurbo :

Yes 2-ways are not used in stock (OEM) applications any more, but the high flow aftermarket ones and they cheaper aftermarket ones are all 2 way. I found this out the hard way when I failed emissions on the LS1 BMW some years ago. I thought all cats where now 3 way...nope

 

Gearheadotaku
Gearheadotaku UltimaDork
2/19/18 8:20 p.m.

These are all 3" in and out

 

vazbmw
vazbmw HalfDork
2/19/18 9:02 p.m.

In reply to Gearheadotaku :

The Citations'?

Gearheadotaku
Gearheadotaku UltimaDork
2/19/18 9:09 p.m.

edited.

 

my photo posts are doing odd things. Now I have to check all the other stuff I've done to see whats there.

CJ
CJ New Reader
2/19/18 9:14 p.m.

Maybe this?  http://www.walkerexhaust.com/catalog/carb-converters/e-catalog-lookup/82629

This one is California and NY compliant. Maybe you don't need a CARB compliant converter?

 

malibuguy
malibuguy Reader
2/19/18 9:24 p.m.

Make sure your tune is right.  A cat wont automatically make magic happen.  If its an older carbd car you most likely need an air pump to make the cat work right as the extra oxygen helps the cat do its job.

I wish I can remember part numbers like I used to.  AP 608227 i believe is an oval heavy loaded 3" 3way cat

alfadriver
alfadriver MegaDork
2/20/18 7:15 a.m.
vazbmw said:

In reply to TenToeTurbo :

Yes 2-ways are not used in stock (OEM) applications any more, but the high flow aftermarket ones and they cheaper aftermarket ones are all 2 way. I found this out the hard way when I failed emissions on the LS1 BMW some years ago. I thought all cats where now 3 way...nope

 

given the very few number of precious metal companies out there that put wash coats to bricks, if someone thinks they have a two way cat, I'd find a new place to buy them.  They clearly have no idea what they are selling.  Which is a pet peeve of mine.

But I will also remind you that a catalyst requires a good control system- so you need to be running a calibration that uses the O2 sensor- preferably one on each bank and one after the catalyst.

vazbmw
vazbmw HalfDork
2/20/18 7:59 a.m.

In reply to malibuguy :

It's a EFI car...and the actual tune is "stock"

 

vazbmw
vazbmw HalfDork
2/20/18 7:59 a.m.

In reply to vazbmw :

Cool Thanks

vazbmw
vazbmw HalfDork
2/20/18 9:15 a.m.

In reply to alfadriver :

The cat is doing what it does within the "stock" system...plus some mods to the stock system. Which is probably why the cat died in the first place. I just need to pass the test this year...then retake again after I pass...then I am done forever

alfadriver
alfadriver MegaDork
2/20/18 9:22 a.m.

In reply to vazbmw :

What is the "stock" configuration, and are you getting any error codes?

NOx can easily be a leak in the exhaust system, or it can be that the engine is running lean, or the catalysts are damaged.  Based on what you have posted, it can equally be any of that.  Need more info to know the issue- what are the emissions numbers you are getting?  Are there error codes? Are all of the original sensors in place and working?  And what engine is in what?

vazbmw
vazbmw HalfDork
2/20/18 11:16 a.m.

In reply to alfadriver :

I have a wide-band 02 sensor, so I can see that it is running at 14.5 - 15 cruising and 12.5 under a light boost.11 under heavy boost

So the mods that are effecting the NOx is that the lack of EGR.

Other mods:

  • High flow little tiny (it's 1/5 the size of the stock unit) Cat from Summit (which I is a 2-way) That is 3 years old
  • Bigger turbo 16T vs 15G
  • 3" exhaust
  • 3" intake and MAF
  • I did turn the boost down to stock for the emissions test.
  • No engine codes.
  • All sensors are in the original locations
  • I am trying to pass with out EGR.
  • My LS1 BMW passes with no emissions equipment except 3 way cats, so I am trying to do this with the 850 Turbo.
  • The car is a 1994 Volvo 850 Turbo
  • 2.3 Liter 5 Cylinder Turbo
  • Stock ECU 

I am embarrassed by the NOx numbers

Test Results:

25/25 Test

  • HC: 71, Allowed 117
  • CO: .01, Allowed .65
  • NOx: 4305, Allowed 821

 

50/15 Test

  • HC: 55, Allowed 120 
  • CO: .01, Allowed .67
  • NOx: 4276 Allowed 907

 

 

 

alfadriver
alfadriver MegaDork
2/20/18 12:07 p.m.

It's not the cat.  And the catalyst, in spite of what Summit thinks, is not a 2 way cat.  They haven't even been made for over 20 years.  Like I said, there are only a handful of companies that make the washcoats on catalysts.  If Summit is really convinced of what they are selling, it's fine to just go out and find another supplier- they don't know what they have.

Still, for some reason, your system isn't switching like it should be.  Even with a crappy catalyst, it will do better than your numbers, as the CO and HC data suggests that it's at least alive.

When you say you have a WB sensor, do you ONLY have a WB sensor, or does the engine run off of a NB sensor as well?  For a '94 car, it's not going to tell you much- since it's pre OBDII.  But there should be a way to self check for codes in a '94.  

It's also not the EGR- it will lower the engine out NOx, sure.  But it's not really required for a halfway decent control system.  I'm sure it would help, but it would not hurt as much as your numbers are suggesting.

If you have just the WB sensor that simulates an output to your controller, do you have data you can share?

Ian F
Ian F MegaDork
2/20/18 12:36 p.m.

In reply to alfadriver :

Maybe it's me, but I'd swear those numbers indicate it's running a bit leaner than it should.  Leaner typically means hotter, which can lead to higher NOx numbers (essentially "burning" air).  High NOx was one of the issues diesels have had for ages, since by design they tend to run lean and hot. 

Since the engine has been modified to pump more are than stock with the turbo, intake and exhaust changes, when you turn the ECU down to stock levels, the engine may be pumping more air than it needs and causing a lean condition.    If you can, I'd find a dyno that will let you play with the tune so you can slowly turn up the fuel until you get closer to the Allowed numbers. That "should" bring down the NOx numbers.

alfadriver
alfadriver MegaDork
2/20/18 1:29 p.m.

In reply to Ian F :

It sure does seem that way.  

And while the higher NOx suggestion is true, I put it more to control than anything else.  5000ppm of NOx isn't that hard to deal with if the system is working and controlling a/f via switching.  I'm thinking that it's lean and not switching or there's a good sized leak in the exhaust.  Given that HC and CO are down pretty well, that at least is an indicator that the catalyst is at least alive.  Not great, but working.

thatsnowinnebago
thatsnowinnebago SuperDork
2/20/18 2:00 p.m.

Sure is nice having actual emissions engineers on this board. I learn so much.

vazbmw
vazbmw HalfDork
2/20/18 4:27 p.m.

In reply to alfadriver :

The wide-band is just for me to monitor the AR. The car is still running the stock O2 sensors for the EFI

vazbmw
vazbmw HalfDork
2/20/18 4:29 p.m.

In reply to alfadriver :

How big does exhaust leak need to be, because there is now leak other than a weep hole (the size a pencil point)?

vazbmw
vazbmw HalfDork
2/20/18 4:32 p.m.

 

In reply to Ian F :

This may be a dumb question, but wouldn't my wideband tell me that I am running lean?

Or, is the true AF ratio is different than what the narrow band EFI O2 sensors see?

Also, one side note, the after market cat is about 1/5 the size of the stock unit. I am suspecting cat size matter too? I am suspecting the more surface area, the more catalyst will be exposed to more exhaust for a longer period of time?

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