Ordered an MBRP Turbo back 409 SS exhaust for the LLY...Some have posted that removing the Cat pipe assembly will cause OBDII to throw out codes like P0401 and P0404....Owners Manuel on LLY says if OBDII SES light is steady, then code is emmisions related, and if OBDII SES light is flashing then code is engine/fuel/drivetrain related...So, when the Cat is removed, and codes P0401 and such are thrown, is the SES light steady or flashing? My SES light comes on steady, then resets itself often, as when I do something simple like fill up my tank.


Sounds like if Cat off, and SES light is Steady, then codes would be emission related, and not a worry, but if SES light is flashing and throwing the Codes P401 et al..then maybe this would mask a more serious issue. I don't have code reader to tell the difference.


any input appreciated





MK

I can't remember the codes others have gotten, but they meant "insufficient EGR flow" as well as one other that kept showing up.


Doesn't seem to be any reason so far why some trucks do it and others don't. I'd like to know if someone figures it out since I'm considering replacing the downpipe on mine as well, even though I'd have to re-install it for emissions tests here where I live.

Ditto with the ability to replace Cat pipe, so I can get it emissions checked.this is why I went with the MBRP set up, seperate flanged Cat pipe assemblys. Still, does the SES flash or show steady with Cat pipe off?

Can't say since I don't recall ever reading about that. Those who've had the problem have just posted about setting codes and getting SES lights, but I don't remember seeing anything about flashing or not...http://www.dieselplace.com/forum/smileys/Ermm.gif

Thanks for reply...I'm trying to get a handle on what to expect...If SES is going to flash, then it'll be a trip to the dealer to reset...maybe?...I've got a super tank in the garage and will install it along with fuel filters...I'm looking hard for EGT and Boost Gauges, pod et al... so I can do a comparison of stock and after market temps for the toys I want...I'd like to try and get a good base line of comparison..





MK

Replaced my cat. with a stock LB7 downpipe last night... Not ever going to put a cat. back under it.. with the MBRP 4" 409ss kit and no Cat. she really sounds nice now, but I still wish it was LOUDER... the only interior(windows up) difference is a bit of resonance before she slips into OD, if the windows are down, its SPOOL SOUND whenever on/off the throttle...





LOVE It...





BIG

Mine has the Cool Duals with cat removed. SES light comes on steady for a few drives, then shuts off. A few drives later it comes back on, then shuts off again. No difference in engine performance either way.


Somewhere I read that the cat is not actually a catalytic convertor, but actually a device to reduce visible smoke...a soot burner. I guess this is to reduce particulate emissions.

Thanks for the post. I'll be putting mine on when I get the EGT/Boost installed. I'll post stock temps, loaded and towing 5K lb boat, then with just cat removed, then with everything replaced with MBRP. I've got a budy who is sound engineer, and I've asked him if there's anything he has that will measure the sound noise inside of the crew cab, stock and after. Don't know when this will all get done, but...I've got 2500 miles on it, and last weekend my mileage on highway unloaded was 20 mpg doing 75...no problems yet with the equipment.


MK

1000 miles on my full dynomax exhaust, no codes as of yet.

Morning Members,


Cat or no cat, not all trucks will send a light to the dash. Seems that approx 70% of them do it on an erratic basis and the rest don't seem to care, go figure just figured you would all want to know. That's why we build the systems both ways to make sure you can get what YOU want!


Mark @ DPPI

Is there any issues with the codes being set due to taking the cat off? Can I just ignore them and keep driving the truck? When I have to get it smogged (I plan to put the cat back on for this) will the codes cause an issue with me passing smog if they are set or will they clear when I put the cat back on?

I get from other posts that the codes thrown are in the 0400 range...this is the emissions/EGR flow area, and should only cause a steady SES light appearance. My SES light comes on and off at will as it is now...If I fill my tank it will cycle on then off and so forth...Owners Manuel says steady SES light is emissions only, and will come on and off..some more tech oriented have posted that this is nothing but a nuissance..I've got MBRP SS 409 turbo Back ordered and will be hooking it up after EDGE/Attitude installed...I want the EGR/ Boost monitors on so I can get #'s for comparison when I start replacing stuff..I went with MBRP because of name recognition, price, and they offer the Flanged Turbo pipe so I should be able to replace CAT when emissions test comes due..I live in Vegas, and the air quality in the city is the pits, so the state/county passed an ordinance that any vehicle 10,000 lb or under has to be smogged...only two countys in the state of Nevada are required by Fed's to smog check, Clark and Washau (Vegas & Reno). The Feds don't mandate diesel checks, but Vegas has circumvented EPA by adding their own ordinance to include the dreaded evil diesel engines, albeight only those that are 10K and under...go figure


I'm not into racing the equipment, just into maximizing performance and longevity...Gm it seems has cooked up Cats on all Duramax's, and redesigned EGR so they can get a uniform assembly line production and be 50 state legal for the diesel...Just leave it up to the GM exec's to take a good product and F%^k it up in the interest of greater profits....Some posts here have indicated that the Exhaust Gas temps with the new EGR and Cat are running very close to Max temp for our turbo chargers..this spells like a turbo charger failure waiting to happen down the line that GM will have to warranty. Anything I can do to lower my exhaust temps is a good thing...I have no knowledge of what if anything removing the cat will do to the ecm programing, performance or mileage, but I'll be watching my numbers to see if there is a change.


god luck, and appreciate any info on your experience's


Ma Ark

Is there any issues with the codes being set due to taking the cat off? Can I just ignore them and keep driving the truck? When I have to get it smogged (I plan to put the cat back on for this) will the codes cause an issue with me passing smog if they are set or will they clear when I put the cat back on?





As far as I know (first diesel since it was implemented here), when they do a smog check here they check for codes and put it on the rollers with a sniffer.


The CAT cuts the NO2? emissions by over half, so if the CAT is gutted they'll know about it.


As far as GM being the culprit on the fifty State emissions equipment, the EPA is responsible for that. Also the EPA has recently started pointing out all the Counties in the USA who don't meet current clean air guidelines and why. That's how we got diesel emission testing in only four of the Counties here, but word has it at least one additional County will be on next year.


You guys who are removing your CAT's may want to keep them just in case diesel emission testing comes to your doorstep in the near future. I'd hate to see what GM gets for one of those new...http://www.dieselplace.com/forum/smileys/Confused.gif

Is there any issues with the codes being set due to taking the cat off?* Can I just ignore them and keep driving the truck?* When I have to get it smogged (I plan to put the cat back on for this) will the codes cause an issue with me passing smog if they are set or will they clear when I put the cat back on?


This is my second Diesel in CA, had em for bout 4 years, I never had to smog or inspect. Just FYI.

I went for it today. I replaced the cat with the straight down pipe I got with my MBRP system. So far no codeshttp://www.dieselplace.com/forum/smileys/Big Smile.gif I ran with the cat back system for a while and had no troubles with it. The sound was great. I like the sound better now that the cat is off. Sounds meaner. Turbo seems to spool up a bit quicker but it could be my imagination.

Cat removal reduced my 1/4 mile ET .08 second. Will dyno soon.


No codes, but I'm running the stock muffler.

I spoke too soon. I got the steady SES light now. I'm going to keep it without the cat until I have to smog it (whenever CA implements the requrement).http://www.dieselplace.com/forum/smileys/Throw Up.gif

For those of you who have problems with codes due to the removal of catalyctic converter, I think i may have found a solution. Bully Dog has recently released their power pup downloader for the LLY's. The power pup has the capability of "scaning and erase Diagnostic Trouble Codes (DTC's)". I also emailed the guy from TTS powers systems asking him if TTS's power module for the LLY (coming out soon) will be able to erase codes. I will let you all know what he says.


Heres a link for the downloader from Bully Dog. http://www.bullydog.com/sale.pl?item=043567


Later


Jack

JUST PULLED THE KITTY OFF AND SWAPPED IT FOR A PIPE OFF A LB7. NO CODES AT ALL RUNS BETTER, TURBO SPOOLS UP FASTER AND YOU CAN HERE IT TO. SOUNDS LIKE A JET TAKING OFF. TRUCK HAS 3,000. MILES EDGE CHIP AND 4 INCH PIPE FROM MUFFLER BACK, BUT WITHOUT NO MUFFLER, STRAIGHT PIPE W/ 5INCH TIP. I LOVE IT

Keep us up to date on this one. If it works, then I'll bet a bunch of guys are going to start doing it. All you LB7 guys that have new exhausts, did you save your old ones, here's where you can get rid of 'em.


Dennis

I ran my early 04 with factory cat removed and no problems. Now have 04 & 1/2 with cat removed. So far no problems but early to tell yet. Also have edge/*** and my own water meth injection and it is putting good power to the ground. Water inj could be huge on this engine I think, because of egr