Help! Lack of power.

[Damian]

Re: Help! Lack of power.

If you look at the temp going into and out of the cat and see how it's doing. If they are close to each other, that's not good. The outlet should always be higher. We used cat temps on our V12 natural gas generator at my last job to see if the cat was going south or not. I got my temp gauge to work so I'll check it tomorrow.

 

[The Bronze]

Re: Help! Lack of power.

If you look at the temp going into and out of the cat and see how it's doing. If they are close to each other, that's not good. The outlet should always be higher. We used cat temps on our V12 natural gas generator at my last job to see if the cat was going south or not. I got my temp gauge to work so I'll check it tomorrow.

I understand the concept. Reality in the automotive industry is something else. I spent a dozen years in the I/M enforcement side, requiring muffler and I/M shops to reinstall or reimburse the non-defective catalyst they replaced based off smell and temperatures. It simply isn't accurate. The theory is sound- hot exhaust gets hotter from the heat of the chemical reaction that occurs in the oxidizing bed. The catalyst temperature runs north of 500 degrees when properly heated up and all that, it's just that in real life the large flow of cooler exhaust gas, heat shielding dissimiliar pipe thickness inlet and outlet and the heat loss through the uninsulated housing, not to mention factor equipped insulated inlet pipes (GM and others) make this test really unsound. Not only that, but take a catalyst away from a stoichiometric mixture(RICH) and the catalyst won't have the necessary O2 to even make a conversion. In that case it's too rich to work and functions just fine after correcting the mixture, thus bringing the O2 back up to 1-3% (non-air injected). I certainly had more than a few that could be identified this way, but I wouldn't be replacing a cat based on this test.

Just my :2cents:

 

[Damian]

Re: Help! Lack of power.

The temps at idle should tell you something though right??

 

[The Bronze]

Re: Help! Lack of power.

The temps at idle should tell you something though right??

My answer still sits at not necessarily. It's just so inconsistent that I don't use it. I am sure you can come up with people that still swearby it and situations that it is correct. I have checked literally hundreds of catalysts and couldn't prove it was reasonably reliable, using fluke infared, cheapo infared, direct contact. It just didn't pan out. A big engine engine, big load, converter located close to the manifolds would all make the test more reliable, but can you still can't put an efficiency number on the temperature output.

I would say that if you were measuring before and after INTERNAL temperatures, then it would be far more accurate, but still not conclusive how well the catalyst works. The gas analyzer takes care of that and does it with the car on the ground. I am lazy like that anyways.

 

[Damian]

Re: Help! Lack of power.

I agree, a gas analyzer is better at seeing what's going on with a cat. I just look at the temps as an indicator of a cat going south. FWIW, my temps are 350ish before the cat and 370ish out at idle after a couple mile drive. That's using an infrared gauge about 2" before and after the cat. I'll end up pulling mine off anyways to look at it. I need to install flanges anyways since I hate the fact that it's one huge piece.

 

[Damian]

Re: Help! Lack of power.

I hooked up my turbo vac lines to my AEM TruBoost instead of my brand new factory boost controller and tried it out. I was able to build boost a lot better now. Looks like I'm gonna have to deal with lower boost until I can get my data logging stuff sometime in the near future.

 

[chuckyuen]

Re: Help! Lack of power.

Finally got around to cutting out the old cat and replacing it with a new Magnaflow unit. Also replaced the O2 sensor just to be safe. Now the truck runs like a champ! Thanks for everyone's help here.

Here's a photo of what fell out of my cat when I cut it off the truck. There were also a bunch of chunks in the downpipe.

 

[Quickstop [UK]]

Re: Help! Lack of power.

Yuck! Glad it works well now!

 

[IpHoOnDyou]

Re: Help! Lack of power.

Finally got around to cutting out the old cat and replacing it with a new Magnaflow unit. Also replaced the O2 sensor just to be safe. Now the truck runs like a champ! Thanks for everyone's help here.

Here's a photo of what fell out of my cat when I cut it off the truck. There were also a bunch of chunks in the downpipe.

That shit looks like fossils!! Glad your truck is runnin better

 

[chuckyuen]

Re: Help! Lack of power.

Thanks! That was less than half of what eventually came out. There was at least that much in the downpipe.