what r some symptoms of a cat getting clogged or just about clogged.....? will it always throw a code or CEL

thanksguys.....im just trying to put two and two together...im really getting annoyed iwth my car

 

Popping noise at highway speeds...... Bad egg smell from exhaust..

 

I would think with your OBDII system you would throw a code as you have O2 sensors before and after your cats. When my OBDI single cat car had a clogged cat, the car would barely accelerate, way down on power. I've read that some guys pull their upstream O2 sensors temporarily to allow exhaust to flow through the small opening and look for improved acceleration.

 

is it a loud popping noise? my loud mouth used to do that at WOT but no egg smell.....my GMMG doesnt do it at WOT but around 2k-2.5 it will pop....could it still be the cats?
also even if warm id go and start my car and if i rev it it will pop...but then drive around it will go back to normal....any suggestions.


wil a bad egr valve cause popping in teh exhaust to ?
"Engine stops after cold start
Engine stops at idle after deceleration
Vehicle surges during cruise
Rough idle"
those are some symptoms of a bad egr ....ive had teh last 3..but there are soo many things thatcan cause this tho....im trying to get some ideas on what to do


also most of my post i am trying to track down my stalling and hesitation....and somewhat poppy exhaust between 2k and 2.5k rpms.....70k on cats most likely origional
thanks guys i really appreciate all ur help

 

TTT

 

id ont know about the surge, but otherwise the problem looks very electrical. plugs, wires, hopefully not opti.

popping is when unburned gas makes it into the exhaust, and most common cause of that is misfire.

 

if you start your car and its poping im guessing your running to rich and the loudmouth exhaust will pop a little, but if you rev to about 5k and let off and she pops tons of times your a little rich, i had the same problem now it pops maybe 1 time or not even 1nce.

go get your car dynoed and do the air/fuel check thing y on it to see if your running rich/lean and at what RPM you are

 

really? hmm opti is new...a few thousand miles on it..im not throwing anycodes....im changing coil/ICM
i only pops when cold revving it or right when u get in the car and start it up even when warm...then its fine after driving for a minute

 

it will only pop one two or three times when cold....it might be time for a tune up .....
would constrictive cats cause a little popping?

 

I've had two bad cats on OBD1 cars. One on my 95 and one on my 93. On the 95 it acted as an early rev limiter. All out of a sudden, the car would not rev past a certain RPM. It was also down in power. By the time I got home, it would barely rev at all. A couple of more starts and it barely idled at 800 RPM. It did not sound right either. (you could tell easily something is not right just by the sound)

Then on the 93, a piece broke off inside it and it was just rattling inside it. I gutted the cat (which is a bad idea IMO) then welded in a new one soon after.

I would think it will set a code right away on a 96 and newer car.

 

madwolf thanks......
im just trying to figure out y my car surges and stalls sometimes and also y everyexhaut i have it sounds like a truck around 2k-2.5k rpms when driving.....do most LT1s do that?

 

would hollowing the cats make that truck popppity poppity get worse or go awat a little?

or is b/c its a free-flowing exhaust?