Catalytic converters questions

[Roland Jacques]

I suspect my 2 Catalytic converters are clogged or close to it.

Is there a good way to confirm or eliminate these suspensions?
Also does anyone no what the second set of O2 sensors (after the cats) are controlling?
Is their anyway to clean a clogged cats?

2001 GMC 3500 10,000 lbs box van with 200,000 plus miles on it.

[Boltazar]

If the cats were not doing what they were supposed to do the O2 sensors behind them would tell the computer that somthing is wrong. And pop a code.

[Roland Jacques]

I know it's suppose to give a code, but i'm not trusting it right now. I was thinking there might be an easy way to confrim they are working good.

[HHOinKY]

Cut them out


You should be able to drop the echaust right where the converter is and look inside. If not, rev it up and see if crap shoots out the exhaust.

My dad was having noises comming from his exhaust and it turned out his converter was broken up and comming out the exhaust.

[HiTechRedNeck73]

your local muffler shop has a way to poke a hole in the exhaust tube and take a pressure reading to know if they are good or not...

I don't know the exact process, but I've had it done before... usually they don't charge to check a cat...

[Jaxom]

HiTech has it...a simple backpressure test will tell you for sure, and it only takes about 10 minutes. Most of the muffler shops around here don't charge for it.

Basically they just punch an 1/8" hole in the exhaust pipe just before the cat, hook a pressure gauge to the hole, and rev the engine. If the backpressure jumps higher than 4 or 5psi, then there's a restriction, and they'll try to sell you a cat. Removing the cat completely is illegal, but some people still do it.

Also, the downstream O2s can't detect a restriction. They only set codes if the chemical reactions inside the cat fail.

[Roland Jacques]

Awesome, thanks guys

[Roland Jacques]

Does anyone know if the "high flow cats deliver any MPG gains?

My trucks not subject to emision tests, and my emisions runing HHO are far lower than non hho trucks. I wonder how it would perform without any cats at all

[HiTechRedNeck73]

Does anyone know if the "high flow cats deliver any MPG gains?

My trucks not subject to emision tests, and my emisions runing HHO are far lower than non hho trucks. I wonder how it would perform without any cats at all

hi-flow cats reduce back pressure and allow exhaust gases to escape faster...

there is a process that some shops use to make hi-flow cats out of normal ones... basically, they take the old cat loose and ram a pipe down in the cat to breakup and reduce restriction in the cat... it's the in-between of hi-flow and no cat at all...

if your vehicle has o2 sensors after the cat, running no cat at all will throw a code on the computer and probably a CEL... the computer compares the front and rear o2 sensors to check if it's working (reduction of o2 gases detected)... without a cat, the gases will be the same and will not be within the expectations of the computer...

[Roland Jacques]

hi-flow cats reduce back pressure and allow exhaust gases to escape faster...

I seem to remember that some back presure has some power benifts when running straight gas ( i think low end torque). But when running HHO and a lean mix, id think back pressure may have no usefull purpose at all. what do you think?

basically, they take the old cat loose and ram a pipe down in the cat to breakup and reduce restriction in the cat... it's the in-between of hi-flow and no cat at all...

LOL, yeah i was thinking about of that also.

If your vehicle has o2 sensors after the cat, running no cat at all will throw a code on the computer and probably a CEL... the computer compares the front and rear o2 sensors to check if it's working (reduction of o2 gases detected)... without a cat, the gases will be the same and will not be within the expectations of the computer...

I wonder why they (the rear O2 sensors) dont see a problem when we run HHO.