1996 Silverado cat converter

I posted awhile back about getting a code for a passanger side
catalytic converter code. P030 I think??? It was something about being
below efficiency or somethign like that. I replaced that o2 sensor
after the cat and cleared the code but it came back again. This truck
has 322,000 on it and dont want to spend too much. I did feel exhaust
leak from wehre the exhaust mannifold meets the exhaust pipe at the
collector but I assume this would not be the cause becasue this is
before all the 02 sensors anyway.

Well, I got to thinking, could I just move the after cat 02 sensor on
that side to the other side exhaust pipe? In essense I would have 2 02
sensors in that side, then I could just remove the bad catalytic
converter and replace with a straight pipe?

The other option is an autozone "generic" cat for 75 bucks but someone
on here said they were made out of cheap material and I am afraid of
going through all that and the light still staying on.

Appreciate any advice.

stryped > wrote:
>I posted awhile back about getting a code for a passanger side
>catalytic converter code. P030 I think??? It was something about being
>below efficiency or somethign like that. I replaced that o2 sensor
>after the cat and cleared the code but it came back again. This truck
>has 322,000 on it and dont want to spend too much. I did feel exhaust
>leak from wehre the exhaust mannifold meets the exhaust pipe at the
>collector but I assume this would not be the cause becasue this is
>before all the 02 sensors anyway.

Sure, why do actual diagnosis? Why not just swap things out at random
and hope that fixes it?

If you don't want to spend too much, though, why are you swapping things
out before determining they are bad?

>Well, I got to thinking, could I just move the after cat 02 sensor on
>that side to the other side exhaust pipe? In essense I would have 2 02
>sensors in that side, then I could just remove the bad catalytic
>converter and replace with a straight pipe?

Maybe, maybe not. Since you haven't determined the problem yet, that
would not seem like a good idea.

>The other option is an autozone "generic" cat for 75 bucks but someone
>on here said they were made out of cheap material and I am afraid of
>going through all that and the light still staying on.
>
>Appreciate any advice.

Why not actually perform the three tests that I suggested originally and
then you'll know where the problem is?

Alternately you can just go swapping things out randomly. Why not put a
new transmission in? It won't hurt anything, only cost you a fortune...
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On May 10, 10:05*am, (Scott Dorsey) wrote:
> stryped > wrote:
> >I posted awhile back about getting a code for a passanger side
> >catalytic converter code. P030 I think??? It was something about being
> >below efficiency or somethign like that. I replaced that o2 sensor
> >after the cat and cleared the code but it came back again. This truck
> >has 322,000 on it and dont want to spend too much. I did feel exhaust
> >leak from wehre the exhaust mannifold meets the exhaust pipe at the
> >collector but I assume this would not be the cause becasue this is
> >before all the 02 sensors anyway.
>
> Sure, why do actual diagnosis? *Why not just swap things out at random
> and hope that fixes it?
>
> If you don't want to spend too much, though, why are you swapping things
> out before determining they are bad?
>
> >Well, I got to thinking, could I just move the after cat 02 sensor on
> >that side to the other side exhaust pipe? In essense I would have 2 02
> >sensors in that side, then I could just remove the bad catalytic
> >converter and replace with a straight pipe?
>
> Maybe, maybe not. *Since you haven't determined the problem yet, that
> would not seem like a good idea.
>
> >The other option is an autozone "generic" cat for 75 bucks but someone
> >on here said they were made out of cheap material and I am afraid of
> >going through all that and the light still staying on.
>
> >Appreciate any advice.
>
> Why not actually perform the three tests that I suggested originally and
> then you'll know where the problem is?
>
> Alternately you can just go swapping things out randomly. *Why not put a
> new transmission in? *It won't hurt anything, only cost you a fortune....
> --scott
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

I put the o2 sensor in becasue I purchased one last year for a code
that came up for it. (I forget the code). Before I could put it in the
check engine light went off and never came back on. So the part I
purchased sat on the shelf. So I had it anyway and thought it was
worth a try. I am assuming the only thing left is the cat. There is no
exhaust leak between the two 02 sensors. There is one at the collector
it sounds like but this is before any sensor. I know I need to fix
that but I really feel it is the cat causing this code. I dont want to
spend 400 bucks or more for the factory cat since the truck has
322,000 on it but I would like to eliminate the light coming on. My
thinking is (maybe I am wrong) but when the light is on it reverts to
closed loop mode and therefore would effect my gas mileage.

I already spent 218 bucks for a new ignition module, spark plugs, and
rotor/cap.

"stryped" > wrote in message
...
On May 10, 10:05 am, (Scott Dorsey) wrote:
> stryped > wrote:
> >I posted awhile back about getting a code for a passanger side
> >catalytic converter code. P030 I think??? It was something about being
> >below efficiency or somethign like that. I replaced that o2 sensor
> >after the cat and cleared the code but it came back again. This truck
> >has 322,000 on it and dont want to spend too much. I did feel exhaust
> >leak from wehre the exhaust mannifold meets the exhaust pipe at the
> >collector but I assume this would not be the cause becasue this is
> >before all the 02 sensors anyway.
>
> Sure, why do actual diagnosis? Why not just swap things out at random
> and hope that fixes it?
>
> If you don't want to spend too much, though, why are you swapping things
> out before determining they are bad?
>
> >Well, I got to thinking, could I just move the after cat 02 sensor on
> >that side to the other side exhaust pipe? In essense I would have 2 02
> >sensors in that side, then I could just remove the bad catalytic
> >converter and replace with a straight pipe?
>
> Maybe, maybe not. Since you haven't determined the problem yet, that
> would not seem like a good idea.
>
> >The other option is an autozone "generic" cat for 75 bucks but someone
> >on here said they were made out of cheap material and I am afraid of
> >going through all that and the light still staying on.
>
> >Appreciate any advice.
>
> Why not actually perform the three tests that I suggested originally and
> then you'll know where the problem is?
>
> Alternately you can just go swapping things out randomly. Why not put a
> new transmission in? It won't hurt anything, only cost you a fortune...
> --scott
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

I put the o2 sensor in becasue I purchased one last year for a code
that came up for it. (I forget the code). Before I could put it in the
check engine light went off and never came back on. So the part I
purchased sat on the shelf. So I had it anyway and thought it was
worth a try. I am assuming the only thing left is the cat. There is no
exhaust leak between the two 02 sensors. There is one at the collector
it sounds like but this is before any sensor. I know I need to fix
that but I really feel it is the cat causing this code. I dont want to
spend 400 bucks or more for the factory cat since the truck has
322,000 on it but I would like to eliminate the light coming on. My
thinking is (maybe I am wrong) but when the light is on it reverts to
closed loop mode and therefore would effect my gas mileage.

I already spent 218 bucks for a new ignition module, spark plugs, and
rotor/cap.

*******
As Scott mentioned, a little time diagnosing is a lot more
successful and a lot less costly than just guessing what
might be wrong. If you didnt see or didnt understand
what he suggested you do, just ask him. He is a nice
fellow and is always helpful on here.

stryped > wrote:
>I put the o2 sensor in becasue I purchased one last year for a code
>that came up for it. (I forget the code). Before I could put it in the
>check engine light went off and never came back on. So the part I
>purchased sat on the shelf. So I had it anyway and thought it was
>worth a try. I am assuming the only thing left is the cat. There is no
>exhaust leak between the two 02 sensors. There is one at the collector
>it sounds like but this is before any sensor. I know I need to fix
>that but I really feel it is the cat causing this code.

Fix it. If you're leaking before or after, the pressure in the cat can be
too low and then it won't work properly and you'll get the error. Check
the whole exhaust system for leaks.

>I dont want to
>spend 400 bucks or more for the factory cat since the truck has
>322,000 on it but I would like to eliminate the light coming on. My
>thinking is (maybe I am wrong) but when the light is on it reverts to
>closed loop mode and therefore would effect my gas mileage.

You are wrong. This is a warning message and has nothing to do with the
actual operation. The output of the downstream sensor is only to tell you
the emission control system isn't working right, it does not provide any
feedback to the engine control algorithm.

The operation of the vehicle is not affected in any way.

>I already spent 218 bucks for a new ignition module, spark plugs, and
>rotor/cap.

This is how cars are, you have ongoing maintenance. Either you want the
light to go out enough to fix the problem properly, or you can live with
the light being on.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

stryped wrote:
>
> On May 10, 10:05 am, (Scott Dorsey) wrote:
> > stryped > wrote:
> > >I posted awhile back about getting a code for a passanger side
> > >catalytic converter code. P030 I think??? It was something about being
> > >below efficiency or somethign like that. I replaced that o2 sensor
> > >after the cat and cleared the code but it came back again. This truck
> > >has 322,000 on it and dont want to spend too much. I did feel exhaust
> > >leak from wehre the exhaust mannifold meets the exhaust pipe at the
> > >collector but I assume this would not be the cause becasue this is
> > >before all the 02 sensors anyway.
> >
> > Sure, why do actual diagnosis? Why not just swap things out at random
> > and hope that fixes it?
> >
> > If you don't want to spend too much, though, why are you swapping things
> > out before determining they are bad?
> >
> > >Well, I got to thinking, could I just move the after cat 02 sensor on
> > >that side to the other side exhaust pipe? In essense I would have 2 02
> > >sensors in that side, then I could just remove the bad catalytic
> > >converter and replace with a straight pipe?
> >
> > Maybe, maybe not. Since you haven't determined the problem yet, that
> > would not seem like a good idea.
> >
> > >The other option is an autozone "generic" cat for 75 bucks but someone
> > >on here said they were made out of cheap material and I am afraid of
> > >going through all that and the light still staying on.
> >
> > >Appreciate any advice.
> >
> > Why not actually perform the three tests that I suggested originally and
> > then you'll know where the problem is?
> >
> > Alternately you can just go swapping things out randomly. Why not put a
> > new transmission in? It won't hurt anything, only cost you a fortune...
> > --scott
> > --
> > "C'est un Nagra. C'est suisse, et tres, tres precis."
>
> I put the o2 sensor in becasue I purchased one last year for a code
> that came up for it. (I forget the code). Before I could put it in the
> check engine light went off and never came back on. So the part I
> purchased sat on the shelf. So I had it anyway and thought it was
> worth a try. I am assuming the only thing left is the cat. There is no
> exhaust leak between the two 02 sensors.


The exhaust leak can still be the cause

> There is one at the collector
> it sounds like but this is before any sensor. I know I need to fix
> that but I really feel it is the cat causing this code. I dont want to
> spend 400 bucks or more for the factory cat since the truck has
> 322,000 on it but I would like to eliminate the light coming on. My
> thinking is (maybe I am wrong) but when the light is on it reverts to
> closed loop mode and therefore would effect my gas mileage.

no your thinking is wrong. The light comes on as a result of a
diagnostic test that the engine control performs once every trip (if the
trip is long enough). The test determines how fast the CAT can respond
to quickly changing Air/Fuel mixture. A leak can mess up the test.
Whether the test passes or fails doesn't affect the engine performance.
The purpose of the test is to determine when the CAT is not working
efficiently. The main danger of having the light on is you may miss
other codes.

-jim






>
> I already spent 218 bucks for a new ignition module, spark plugs, and
> rotor/cap.

On May 10, 2:50*pm, (Scott Dorsey) wrote:
> stryped > wrote:
> >I put the o2 sensor in becasue I purchased one last year for a code
> >that came up for it. (I forget the code). Before I could put it in the
> >check engine light went off and never came back on. So the part I
> >purchased sat on the shelf. So I had it anyway and thought it was
> >worth a try. I am assuming the only thing left is the cat. There is no
> >exhaust leak between the two 02 sensors. There is one at the collector
> >it sounds like but this is before any sensor. I know I need to fix
> >that but I really feel it is the cat causing this code.
>
> Fix it. *If you're leaking before or after, the pressure in the cat can be
> too low and then it won't work properly and you'll get the error. *Check
> the whole exhaust system for leaks.
>
> >I dont want to
> >spend 400 bucks or more for the factory cat since the truck has
> >322,000 on it but I would like to eliminate the light coming on. My
> >thinking is (maybe I am wrong) but when the light is on it reverts to
> >closed loop mode and therefore would effect my gas mileage.
>
> You are wrong. *This is a warning message and has nothing to do with the
> actual operation. *The output of the downstream sensor is only to tell you
> the emission control system isn't working right, it does not provide any
> feedback to the engine control algorithm.
>
> The operation of the vehicle is not affected in any way.
>
> >I already spent 218 bucks for a new ignition module, spark plugs, and
> >rotor/cap.
>
> This is how cars are, you have ongoing maintenance. *Either you want the
> light to go out enough to fix the problem properly, or you can live with
> the light being on.
> --scott
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

Ok. Is it hard to get the three botls off at the collect on a 322,000
mile engine? (I just dont want to break something off and create a
bigger problem). Also, If I take the collector off and replace the
gasket (I am assuming this is where the leak is coming from) and
fixing the exhaust leak sdoes not fix the code, I will have to take
the collector off again to replace the cat to prooerly weld a new one
in there.

stryped wrote:
> I posted awhile back about getting a code for a passanger side
> catalytic converter code. P030 I think??? It was something about being
> below efficiency or somethign like that. I replaced that o2 sensor
> after the cat and cleared the code but it came back again. This truck
> has 322,000 on it and dont want to spend too much. I did feel exhaust
> leak from wehre the exhaust mannifold meets the exhaust pipe at the
> collector but I assume this would not be the cause becasue this is
> before all the 02 sensors anyway.

Actually ANY leaks in the exhaust prior to the last sensor can cause codes.
I have even seen cases where a high flow muffler caused a cat code.

The reason is that the way the system tests the converter and sensors is
actually simple. It cycles the fuel system from rich to lean very
rapidly and looks at the voltages from the sensors to tell it if the
system is responding properly. The leak will throw the system off and
set a code.

Another one that can drive you nuts is a vacuum leak around the
manifold. The engine only sees a difference at the O2 sensor that it
cannot account for and will set lean codes and cat codes.

>
> Well, I got to thinking, could I just move the after cat 02 sensor on
> that side to the other side exhaust pipe? In essense I would have 2 02
> sensors in that side, then I could just remove the bad catalytic
> converter and replace with a straight pipe?

Sure if you don't mind failing inspection and facing a federal fine for
tampering with the emissions controls. Removal of a cat is a VERY big NO
NO....

>
> The other option is an autozone "generic" cat for 75 bucks but someone
> on here said they were made out of cheap material and I am afraid of
> going through all that and the light still staying on.
>

Fix the exhaust leak and then use a good scan tool and watch the
voltages from the O2 sensors while driving around.
All it takes to set a code is a lazy sensor. Bad cat is also possible.
220 bucks for a new Y pipe and cat isn't bad.
That is an Eastern Direct fit for a 305/350 application with single exhaust.

If you have the dual converter/pipe system the unit is 264 bucks.


--
Steve W.

stryped > wrote in
:

> There is no exhaust leak between the two 02 sensors. There is one at
> the collector it sounds like but this is before any sensor.


Do you have any idea how exhaust emission controls work?

You've just given a gigantic clue as to your problem, if you only
understood what you just said.


--
Tegger