Another exhaust question

[Jiggie]

hey all. So I need to replace my cats in my 99 burb obs 4wd with the 5.7. I was planning on buying some shorty headers and replacing the y pipe and cats and doing a cat back. But I can't afford that or even just the y pipe so I need to know the best way to Make my bad cat issue go away on the cheep along with the check engine light. It sucks that the catless y pipes are just as expensive as the catted ones lol.

 

[BIG_KID]

Replace cats with strait pipe
Put black electrical tape over check engine light

 

[kennythewelder]

I posted this some time back. I still have my home made 02 simulators on my truck. They work grate, and they will not trip a CEL. My truck has true dual exhaust. I removed the exhaust pipe where the cats are, then took a steel rod, and a hammer to bust the honey comb material out from the inside of the cats. This is what restricts the exhaust flow. When I was done braking out the honey comb from the inside of the cats, they was nothing at inside of the cats. I had to cut one of the cats from the exhaust pipe to get to the inside of it with the steel rod. You can skip gutting the cats and replace them with a straight pipe, but still do the 02 simulator trick, and as long as there is a little piece of honey comb inside the first cat, it will work.

First off, know that by removing your cats, your truck will not pass emissions testing. But if you want to remove your cats, or you have already, here is how to trick the rear 02 sensors, so that you don't need to reprogram the ECM. click the web sight and you can order these, http://www.bigdaddiesgarage.com/mini-cat-cel-fix.html or you can do what I did and build your own. I used 4 sparkplug non foulers. I took the honey comb that I removed from my cats. I used a hack saw, and a bench grinder to make the honey comb fit into the spark plug non fouler. If you do this, use a dust mask, or even better a respirator, grinding the honey comb makes a lot of dust. Also if you pull the hack saw to ruff cut the honey comb, it works better. If you try to push the saw, its to aggressive, and the honey comb is brittle.The little pieces of honey comb you need, will need to fit between the 02 sensor and the non fouler, that is next to the exhaust pipe, inside the non fouler, it will look like the pic on the web sight where you can buy them. They will need to be about 1/2 thick, and need to fit just slightly loose. You don't want to crush the honey comb when you put the 2 non foulers together. It will crumble and not work. Also be sure that the honey comb is not clogged up. I just used my breath to blow the honey comb clean once I got it to fit inside the non fouler. This gives the rear 02 sensor what it is looking for, it thinks there is still a cat.

You must be registered for see images attach

 

[kennythewelder]

Oh and I have summit shortys on my truck. Been on there for several years. Good product @ a good price, but you will need to strip the paint, and repaint them with some VHT header paint.

You must be registered for see images attach

 

[Jiggie]

I posted this some time back. I still have my home made 02 simulators on my truck. They work grate, and they will not trip a CEL. My truck has true dual exhaust. I removed the exhaust pipe where the cats are, then took a steel rod, and a hammer to bust the honey comb material out from the inside of the cats. This is what restricts the exhaust flow. When I was done braking out the honey comb from the inside of the cats, they was nothing at inside of the cats. I had to cut one of the cats from the exhaust pipe to get to the inside of it with the steel rod. You can skip gutting the cats and replace them with a straight pipe, but still do the 02 simulator trick, and as long as there is a little piece of honey comb inside the first cat, it will work.

You must be registered for see images attach

Got ya!! Yea I figure if I have to do the manifold gasket I should install some headers. This is my first v8 vehicle so this is all new and my head hurts from all the research lol. This is my family vehicle and daily driver so I want to keep it as reliable as possible. I think I might just buy the ones in the link just cause I don't have many tools (because someone decided they needed my tool box more than me). Now do I need one for all the o2 sensors or just the rear one? I think I have 3 on mine but don't remember.

 

[kennythewelder]

The simulators only go on the rear 02 sensors, behind the cats. Shorty headers are the easiest to install. They will give you better take off power. Long tube headers are better at higher RPMs, but need to be welded in at the exhaust pipe, unless you are a good welder. You should also know that it is very common to fight exhaust leaks with headers. It took several tries to get mine leak proof. If you install headers, be prepared to replace exhaust manifold gaskets about every year or two. I tried just about every gasket they make, I find the Mr Gasket header gaskets work best for me.

 

[Big D]

get on paypal credit, buy Magnaflow catalytic converters that bolt right up, you get 6 months to pay off headers and cats with no interest while building credit and driving around not gross polluting... ( all though hardly anyone gives a ****)

 

[kennythewelder]

Big D has a good point. High flow cats are the rite way to do the job. They flow as well as no cats or very close to that anyway. You may still need the simulators, because the rear 02 sensors may not be in spec due to the difference between HF and OE cats. I have seen this happen before.

 

[GMRedline]

I just did a full manifold back replacement on my suburban. I have HP Tuners so I disabled the rear O2s. If you wanted to keep them functional, you could just add a couple of more bungs after the cat for the rear O2s.

http://www.gmt400.com/threads/finally-installed-my-custom-3-exhaust.35081/#post-959588

I have about $500 into but I also have a welder so it was a full diy.

 

[GarrettGmc]

Anyone know if the high flow cats would still pass smog check in Ca.