catalytic converter?

I read somehwere that a clogged catalytic converter could cause a problem similar to what i am experiencing. i.e. (bogging down and sluggish, surging with power). Could this be a likely cuase? My exhaust smells very strong and of rotten eggs so this could be it. I wasn't even sure if my car has a catalytic converter.

I read somehwere that a clogged catalytic converter could cause a problem similar to what i am experiencing. i.e. (bogging down and sluggish, surging with power). Could this be a likely cuase? My exhaust smells very strong and of rotten eggs so this could be it. I wasn't even sure if my car has a catalytic converter.


If you smell rotten eggs you have a catalytic converter...place your pressure gauge in the air pump check valve pipe fitting located at the valve cover and measure pressure should be below 10psi at idle...if it shoots upward the higher it goes the more its ''' plugged'''...

the reason you smell rotten eggs is your engine is too rich and the cat is working over time... cat should only work when the engine is warming up.... if you replace the cat with a new one and first don't address the mixture problem your vehicle may go up in flames....as the new cat will,,, with max efficiency start to glow a very bright red and then you will smell the carpet burning...



It is very possibe with the cat plugged the EGR now has more exhaust gas pressure and this is now causing the problems ..these are all interrelated...

you should have an old timer with experience with this type of vehicle look at it...

If you smell rotten eggs you have a catalytic converter...place your pressure gauge in the air pump check valve pipe fitting located at the valve cover and measure pressure should be below 10psi at idle...if it shoots upward the higher it goes the more its ''' plugged'''...

the reason you smell rotten eggs is your engine is too rich and the cat is working over time... cat should only work when the engine is warming up.... if you replace the cat with a new one and first don't address the mixture problem your vehicle may go up in flames....as the new cat will,,, with max efficiency start to glow a very bright red and then you will smell the carpet burning...



It is very possibe with the cat plugged the EGR now has more exhaust gas pressure and this is now causing the problems ..these are all interrelated...

you should have an old timer with experience with this type of vehicle look at it...

Thank you so much for the help! I really have a good feeling that this is the issue and i can finally get my car working again!! I know a mechanic who knows a lot about these cars and i'll talk to him about it (he's located in Hull if you've ever been there "Robin's Garage"). I think i might have him take the cat off and while he's at it install a flowmaster 40 for me (i can't wait!)

I also heard if you wack the cat with a screwdriver or something and you hear a dull thud instead of a more hollow noise then its plugged. And sure enough i heard the dull thud!

I also heard if you wack the cat with a screwdriver or something and you hear a dull thud instead of a more hollow noise then its plugged. And sure enough i heard the dull thud!

Somebody saw you coming, didn't they!

You're going to hear a thud regardless. The substrate material is ceramic honeycomb, you're not going to get any sort of hollow noise out of that.

Somebody saw you coming, didn't they!

You're going to hear a thud regardless. The substrate material is ceramic honeycomb, you're not going to get any sort of hollow noise out of that.

lol, ok then. I guess i'm going to take apart the carb this weekend.

lol, ok then. I guess i'm going to take apart the carb this weekend.


why are you going to mess up the carb ????

get the vehicle checked out by that old guy....stop wasting your money chasing your tail...chances are you have a plugged cat and because you have a 1983 the emisions testing is not required....


since you don't know how to use/test out your engine,,, bring to someone who does and ask questions as he looks at it ...

my quadrajet lasted 17years 380,000mi and I only replaced the in line gas filter thats it....this is not a simple job and I doubt you have the training to do this properly...

why are you going to mess up the carb ????

get the vehicle checked out by that old guy....stop wasting your money chasing your tail...chances are you have a plugged cat and because you have a 1983 the emisions testing is not required....


since you don't know how to use/test out your engine,,, bring to someone who does and ask questions as he looks at it ...

my quadrajet lasted 17years 380,000mi and I only replaced the in line gas filter thats it....this is not a simple job and I doubt you have the training to do this properly...

Yeah your totally right. Its just people kept turning me back to a carb problem and then a cam lobe problem, but this car has 49,000 miles!! So it COULDN'T be anything that serious. I just did the vacuum test and was happy with the results proving its a cat related problem. Vacuum resides at around 17 "when i hooked the gauge to the vac line that goes to the MAP sensor" and once i stepped on the gas, the gauge went down about 8-10 inches. btw that is an A$$ LOAD of miles you got on that quadrajet.

hey j Cat "or anyone else," i think there might be some debris in my carb "from changing the fuel filter and putting the additive in the tank and thats why i might need to take it apart, or do I? Is there anything i could do without the burden of taking it apart?

hey j Cat "or anyone else," i think there might be some debris in my carb "from changing the fuel filter and putting the additive in the tank and thats why i might need to take it apart, or do I? Is there anything i could do without the burden of taking it apart?


when changing this filter it is very difficult to get contaminates into the carb....also if you still think fuel supply is a problem you can replace fuel filter again and test the fuel pump pressure...cut open the fuel filter and see if the insides of the peats are loaded with rust as this is a possibility... if the fuel filter ruptured then it is possible that the carb has problems...if not leave it alone...



finally I see you have used you vacuum gauge to troubleshoot your engine this is how you can stop guessing as your results to me indicate a restricted exhaust....


the cat on your vehicle if original should be a very large flat bottomed type this is the good high quality cat....the smaller round type used in 84 has plug up issues....

They stopped using beaded converters in the late 1970s, j cAT.

They stopped using beaded converters in the late 1970s, j cAT.

I disagree ....MY 1983 delivered in june 1983 ordered from factory had the large flat bottomed cat...this is the one that lasts almost forever...the cheap rounder smaller ones plug up ...1984 this was when it was changed...as the same applies... my 1984 still has the bad one on it...

ya you got the one I'm talking about ....1983 had the expensive platinum beads in it...it was huge..

I disagree ....MY 1983 delivered in june 1983 ordered from factory had the large flat bottomed cat...this is the one that lasts almost forever...the cheap rounder smaller ones plug up ...1984 this was when it was changed...as the same applies... my 1984 still has the bad one on it...

ya you got the one I'm talking about ....1983 had the expensive platinum beads in it...it was huge..

My 1982 Impala had the honeycomb cat in it. If you had an '83 with the octagon cat, it was retrofitted. Regulations enacted in 1979 effectively ended the older beaded cat - for lack of NOx control.

So even though i have the bigger cat which "lasts forever" it could still get plugged right? For the past 8 years my car has been turned on and turned off without a good highway run so i'm guessing carbon has built up as a result.

So even though i have the bigger cat which "lasts forever" it could still get plugged right? For the past 8 years my car has been turned on and turned off without a good highway run so i'm guessing carbon has built up as a result.

I've had more problems with those old beaded cats, the ones 'j cAT' states last forever, getting plugged. Perhaps I am an anomaly, perhaps not. Either way, the beaded cats are very restrictive by design, where the monolithic, honeycomb ones of newer design are much less so.

A very rich running engine can kill a cat (as well as the 02 sensor). Likewise, an engine with a chronic misfire can kill a cat. Both due to overheating as the unburned hydrocarbons burn inside the cat.

If you have a simple carbon buildup, a good, hard run can 'bake' the cat and remove the restriction.

I've had more problems with those old beaded cats, the ones 'j cAT' states last forever, getting plugged. Perhaps I am an anomaly, perhaps not. Either way, the beaded cats are very restrictive by design, where the monolithic, honeycomb ones of newer design are much less so.

A very rich running engine can kill a cat (as well as the 02 sensor). Likewise, an engine with a chronic misfire can kill a cat. Both due to overheating as the unburned hydrocarbons burn inside the cat.

If you have a simple carbon buildup, a good, hard run can 'bake' the cat and remove the restriction.

did the newer cats from the early 80s still come with Platinum in them? i have to change out the cat in my 83. not because it has died, but because the flange has rotted off the end that meets the intermediate pipe.

Platinum and palladium are the catalyst metals, so yes- they all have them. Plus, the dual stage cats (mandated from 1979 onward) have rhodium also, to control NOx.

My 1982 Impala had the honeycomb cat in it. If you had an '83 with the octagon cat, it was retrofitted. Regulations enacted in 1979 effectively ended the older beaded cat - for lack of NOx control.


I have seen regional differences with vehicle emissions....this is pehaps why your 82 and the 1979 regulations you mention caused my vehicle to have the older much larger cat...while yours had the honeycomb...

In any case with GM vehicles built at that time these smaller cats were plug prone.... 60-80,ooomi and they plug up...this is with the 1980's models ...later the cat improved and only if you had some failure that caused a poor engine operation would you have issues with this part...

my 1983 was built in may 1983..

did the newer cats from the early 80s still come with Platinum in them? i have to change out the cat in my 83. not because it has died, but because the flange has rotted off the end that meets the intermediate pipe.


this can be repaired...do not replace the cat ...I did this many times....parts are available to clamp on to the weld remains on the cat pipe you then mount your new flange replacement part two pieces and two bolts....I used s/steel bolts so when this need replacement again it come off easy.....double nut the new flange hardware...

did the newer cats from the early 80s still come with Platinum in them? i have to change out the cat in my 83. not because it has died, but because the flange has rotted off the end that meets the intermediate pipe.

yeah my flange is rotted too.

i'm getting rid of the cat altogether because they don't check emissions on my car because of its age.

i'm getting rid of the cat altogether because they don't check emissions on my car because of its age.


the removal even though not emission tested may be a violation of law ...so you should not advertise your intentions..

the removal even though not emission tested may be a violation of law ...so you should not advertise your intentions..

well in that case "i'm keeping the cat" ;)

If you change the cat yourself DO NOT simply throw it away! I changed the cat on my 84 myself about 2 months ago. The "universal" cat, clamps, and extension pipes cost me about $110. I took the old cat to a scrap metal yard and got $60 bucks cash. I have been told that the older flat cats are worth even more.

If you change the cat yourself DO NOT simply throw it away! I changed the cat on my 84 myself about 2 months ago. The "universal" cat, clamps, and extension pipes cost me about $110. I took the old cat to a scrap metal yard and got $60 bucks cash. I have been told that the older flat cats are worth even more.

Thats definately good to know!

I have seen regional differences with vehicle emissions....this is pehaps why your 82 and the 1979 regulations you mention caused my vehicle to have the older much larger cat...while yours had the honeycomb...

In any case with GM vehicles built at that time these smaller cats were plug prone.... 60-80,ooomi and they plug up...this is with the 1980's models ...later the cat improved and only if you had some failure that caused a poor engine operation would you have issues with this part...

my 1983 was built in may 1983..

Perhaps your car was built in Canada for the Canadian market.

If the VIN starts with a '2', it's Canadian manufactured.

The 1979 cat change was a federal mandate, so it should have been an across the board thing. CA was a year earlier in 1978.

Perhaps your car was built in Canada for the Canadian market.

If the VIN starts with a '2', it's Canadian manufactured.

The 1979 cat change was a federal mandate, so it should have been an across the board thing. CA was a year earlier in 1978.

My caprice says it was built in canada, haven't noticed the "2" in the vin but i'll check.

i have an inspection coming up and had to replace the cat because it was rotted and leaked (yeah j cAt it had to be replaced :disappoin) after replacing it the car started running terrible. the car chugs after being warmed up and today i am getting a strong odor of sulfur. i have had a service engine light for a while now, i finally pulled the codes today. i got a code 15 which is engine temp sensor... which is not connected (corroded wire) if i remember right this will cause the comp to make the engine run rich, could this be causing the sulfur smell too? its an 83 with 305

i have an inspection coming up and had to replace the cat because it was rotted and leaked (yeah j cAt it had to be replaced :disappoin) after replacing it the car started running terrible. the car chugs after being warmed up and today i am getting a strong odor of sulfur. i have had a service engine light for a while now, i finally pulled the codes today. i got a code 15 which is engine temp sensor... which is not connected (corroded wire) if i remember right this will cause the comp to make the engine run rich, could this be causing the sulfur smell too? its an 83 with 305


the temp sensor should be connected and this will then cause the computer to work the engine in closed loop mode so that it will respond correctly ...

upon installing a new cat to an old vehicle this can be dangerous as the new cat being very effecient will generate a tremendious amount of heat [glowing red] and cause your vehicle to catch on fire...If the mixture/exhaust is very much loaded with unburned fuel....

Installing any new exhaust part will smell as oils burn off..


perhaps the O2 sensor was damaged with the cat replacement or they disconnected something...


one thing you must check is the heat riser this is at the exteme end/output of the exhaust manifold make sure this is fully open and if they broke it or is rotten use stainless wire to keep it forced open this will cause a problem like yours also...