Symptoms of a Clogged Catalytic Converter?

My truck is running quite well, but has a problem, whenever I accelerate too hard (usually on even a slight incline) my engine misfires a little. I only really notice this in third gear. But it has happened in fourth as well.
After getting the RPMs up over 3000 i usually smell a sort of sulfur smell. This leads me to suspect my catalytic converter. However would that cause my car to jerk like it does? it feels like a misfire but i could be wrong. I'm going to replace the fuel filter soon enough, but how much HP would a clogged cat rob? and do i need to get a new one or can i just bore it out and slap it back on? I live in ID so im not particularly worried about emissions testing...

yes my old jeep cherokee did that but it was cause my muffler was f'd up and causing all the exhaust to have back pressure...so i suppose a cat will do the same

the miss fire could be something wrong with the engine it's self ,have you pulled any codes or has the cel light came on ?? you may want to look at that prospect before cutting off your cat ...could be something easlilly fixed or adjusted etc....

or...


i also live in a area thats non emission regulated...personally i cut it off if it were clogged but ..... i am sure many will tell you that may affect engine performance to some degree.like cutting it off may take away from the bottom end or something to that effect ,you could cut it off then weld a proper length straight piece of exhaust pipe in it's place ...may cure the affects of engine performance.i dont wont to get into a discussion about muffler performance here but some may say "yeah cut it off " some may say "yeah just weld on a new muffler after you do with out replaceing it with a replacement pipe" etc ...... you know


i'm looking at my LMC catalog right now and they want $289.95 for a new one .....so if you dont want to fork out that type of money then cutting it off and putting in a replacement pipe may be a option for you .

Sulfur smell is usually related to the cat. Before just replacing the cat, I'd check to see if the engine is running rich. A rich condition contributes to clogging the cat and the sulfur smell and such.

MrShorty said:

Sulfur smell is usually related to the cat. Before just replacing the cat, I'd check to see if the engine is running rich. A rich condition contributes to clogging the cat and the sulfur smell and such.

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I'm sorry i don't understand what you mean by rich, could you please elaborate?

Rich = too much fuel, not enough spark

Lean = not enough fuel

what would cause it to run rich or lean? and how do i test for this?

if i were to take a stab at that question most likelly be from bad o/2 sensor....dirty maf / throttle body ...worn or clogged pcv vavle.on my x when i bought it the whole upper intake had a layer of sludge little more than 1/8 thick all on both the inside and throttle body themselves.after soaking the upper intake in gas i managed to get every bit of crap out of it ..looked like new .no wonder it suffered a aneurysm (lol) but it ran rich and i to smelled sulfur smells ...so maybe the reason why yours is running rich is that the engine air management systems need a good cleaning .

my 2005 colorado requires the upper intake system cleaned every 30k and now i'm about 20k over due but when it acts up the truck will idle fine when cold but move a little down the road and put the clutch in to stop and the rpm's die down almost killing the motor (rough low idle condition) .

Mine is doing similar. Would a bad o2 sensor throw a code? Need to replace pcv and fuel filter first thanks

My 2004 Explorer has similar issues. I noticed it only revs up to 3300 RPM with no load, has Bank #1-Rich and Bank#2-Lean. Mil light will come on if it idles for a while. Now, I'm suspecting the Converters. I have replaced Intake Manifold seals, cleaned the MAF Sensor, changed plug wires and since I have the plugs on hand, I will change them soon, checked for vacuum leaks and replaced a couple of "suspicious" hoses. I have a new PCV Valve on the way and it should be in on Tuesday. I may replace the Fuel Trim Oxygen Sensors, too.

I just got this two weeks ago and it has been quite an experience! I thought I knew what I was doing, but this has turned into a parts "Shotgun Job"!

Good luck with your pickup.

ParkerRocker said:

My truck is running quite well, but has a problem, whenever I accelerate too hard (usually on even a slight incline) my engine misfires a little. I only really notice this in third gear. But it has happened in fourth as well.
After getting the RPMs up over 3000 i usually smell a sort of sulfur smell. This leads me to suspect my catalytic converter. However would that cause my car to jerk like it does? it feels like a misfire but i could be wrong. I'm going to replace the fuel filter soon enough, but how much HP would a clogged cat rob? and do i need to get a new one or can i just bore it out and slap it back on? I live in ID so im not particularly worried about emissions testing...

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The transmission has 3/4 servo is low on fluid or is going out. Yes the O2 sensors with send a code. check the fluid of transmission and clean MAF and TBI.

When my cat was going bad, I first noticed a huge decrease in power and performance. The back pressure started blowing the two hoses of my EGR tube, and the heat started melting plastic components like cable sheathing. Blockage was caused by an overly rich fuel mixture.

luvmonterey said:

When my cat was going bad, I first noticed a huge decrease in power and performance. The back pressure started blowing the two hoses of my EGR tube, and the heat started melting plastic components like cable sheathing. Blockage was caused by an overly rich fuel mixture.

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Now THAT is a Catalytic Converter meltdown failure! Yikes!