2nd Gen Non-Engine/Transmission cat or resonator??

[DISPATCH]

i just straight piped my brothers truck i took out the muffler a while ago and i just took out the other thing ... is it a resonator or a catalytic convertor?? the truck was not running well. like i could not get over 60 mph going up hill unloaded. now pulling a small trailer and two guys 3/4 tank of fuel i was doing the same hill at 75mph and climbing. so was the problem a restricted cat or what??

 

[Dan_69GTX]

If you are referring to the 97 truck - yes, that should have been a cat. Yes, it sounds like a restricted Cat.



Look at the inside of it - does it look all plugged up?



Too late now, but before you take it out you can do a back pressure check - right before and after the cat - if there is much of a difference in pressure, yea - your cat is plugged.



Dan

 

[TPlasek]

What is the magical pressure difference which is considered to be too much thus rendering the Cat plugged. I have a 93 Surburban (gas) the recently started to lack power and develope an overheating problem at the same time. I nstalled new radiator, new thermostat and fan clutch, but the problem is still there. The power is very flat now...



Tim

 

[Dan_69GTX]

Backpressure is relative - depending on what engine, type of exhaust (turbo or not), size of pipe, etc.



"Generally" a 1-2psi difference indicates a plugged cat - at around 2500 rpm.



For a good explaination go here:

http://www.babcox.com/editorial/bf/bf19922.htm



That article also addresses the reasons why a converter gets plugged. However it is geared more toward a gas motor instead of a diesel.



Dan

 

[TPlasek]

You would have to have a pretty accurate gauge to be able to measure a difference of a couple of psi. Plus those are hot exhaust gasses you are measuring.



Has anyone done this???

 

[Dan_69GTX]

Yes,



There are several manufactures of these gauges - snapon eepv500a is a good one - yes expensive. There are cheaper ones that will work ok



Any exhaust shop that is remotely good will have one of these.



You can even find them on E-Greed every now and then.



Dan

 

[DISPATCH]

i looked through the cat and i could just barley see light on the other end

 

[DISPATCH]

how does the cat get plugged. doe sit mean there is somthing wrong with the motor??

 

[HerbW]

Better off without a CAT!

Blue,

If your engine is BOMBED and blows alot of black smoke when you get on the go petal, that helps plug it up. If you use alternate fuels other than recommended fuel it will also plug it up. I have seen the honeycomb out of a cat and it is very small holed. Put a bright light at one end and look in the other. Even if you see through, it is plugged looking from the start. A lot of people replace the CAT with a pipe from the Dodge dealer or knock the guts out of it and it still looks "official"! They sound better without the honeycomb! Good luck, Herb

 

[BigPapa]

TPlasek, to answer your question on the gasser, try replacing your oxygen sensor in the exhaust. I had a '91 Chevy P/U that increased almost 5 MPG when I replaced mine. Ran alot better, too.

 

[DISPATCH]

thanks herb. my brother just bought the truck at the begining of the year we drove to kentucky to buy it so i don't know the history of fuel that was used and there are no bombs ... . yet but i will take a flsh light to it. thanks again every body

 

[Dan_69GTX]

Certain fuel addatives can also hurt a cat.



Check to make sure they are safe for a cat! Most of the popular ones are.



Hmmm wonder if running a high sulfur fuel would affect one? - such as the dyed off road fuels?



Dan

 

[CFAR]

On a gasser the output of the CAT should be around 100 degrees f hotter than the input, or its not working.



You can use an infared thermometer to check.



Don't know about a diesel, though I would ASSUME it operates on the same principles.