Catalatic Converter O2

When my car was on the lift, my buddy & I noticed the o2 sensor for the cat. was infront of it, so techically speaking if I ran a testpipe, the o2 sensor wouldn't catch it?

I'm not as familar with the Alero as I am with my previous car (had 3 f***in' o2 sensors, a PAIN) so I maybe wrong, this also leads me to the idea that I don't need the hi-flow cat with the o2 bung either...

There are 2 oxygen sensors on the Alero, one in front (upstream) of the catalyst and one behind (downstream). You can safely remove the O2 sensor downstream of the catalyst, since it's sole purpose is to monitor operating efficiency of the converter. You will need to get an O2 simulator to avoid a check engine light if you decide to remove the downstream sensor.
The upstream sensor is responsible for monitoring air-fuel ratios when the PCM is operating in closed-loop, and helps to keep fuel trims close to 14.7:1 for maximum fuel mixture burn. It works in combination with the MAF, MAP, and other sensors and is vital to the operation of your vehicle - so don't remove it.
If you want to run a test pipe for tuning purposes, you will set a check engine light for Low Catalyst Efficiency - the PCM can tell if there are outrageous levels of nitrogen oxides and other nasty toxins in your exhaust...unless you run the aforementioned simulator. Please don't drive your car on the street without a converter - it's there for a reason.

yeah I don't plan on removing the cat, just was curious. thanks for the info.

[-Alero-]

which O2 sensor is Bank 1 and which O2 sensor is Bank 2?

[jabartram]

bank2 is after the cat.

[-Alero-]

Originally posted by jabartram@Jan 15 2006, 07:05 PM
bank2 is after the cat.

Quoted post

what!? there is no O2 sensor after the cat........

theres only 1 at the cat....i think thats what you mean.


well for osme reason my car is saying "Too Lean Bank 1"

so its like........wtf now....

[jabartram]

i have an 02 after my cat.

[jackal2000]

a high flow cat is a waste of money anyways. hold what you got.

[jabartram]

Originally posted by jackal2000@Jan 16 2006, 01:26 AM
a high flow cat is a waste of money anyways. hold what you got.

Quoted post

It made a big difference on my car, after the headers were installed.

[Redog]

With headers, a high flow cat is good, but wihtout, no it doesn't do anything

The o2 is before the cat? By any chance is this car a Cavalier? I know the J bodies have the o2 before the cat, but on the Alero/GA they are after the cat.

If your talking about an Alero, are you sure you're not thinking of the res

[-Alero-]

Originally posted by Redog@Jan 16 2006, 01:30 PM
With headers, a high flow cat is good, but wihtout, no it doesn't do anything

The o2 is before the cat? By any chance is this car a Cavalier? I know the J bodies have the o2 before the cat, but on the Alero/GA they are after the cat.

If your talking about an Alero, are you sure you're not thinking of the res

Quoted post

when i look(ed) under my car, i always saw the O2 bung in the cat. and the O2 sensor went directly into the Cat on the side.....

so i dont under stand how you guys have yours after the cat.....

andways, so if i have an O2 simulator in my downstream, and you guys say Bank 1 is the upstream, why does it say im running too lean in bank 1

[Fast Eddie]

Originally posted by jabartram+Jan 15 2006, 05:05 PM--><div class='quotetop'>QUOTE(jabartram @ Jan 15 2006, 05:05 PM)</div><div class='quotemain'>bank2 is after the cat.

Quoted post

[/b]

Bank two is the one side of the V (I don't a 6 so I don't know which one) bank 1 is the other side of the V and the downstream on is after/in the cat. So the V6s should have three, one on the front side exhaust manifold, 1 on the firewall side manifold and one after/in the cat.

Originally posted by jabartram+Jan 16 2006, 06:32 AM--><div class='quotetop'>QUOTE(jabartram @ Jan 16 2006, 06:32 AM)</div><div class='quotemain'><!--QuoteBegin-jackal2000@Jan 16 2006, 01:26 AM
a high flow cat is a waste of money anyways. hold what you got.

Quoted post

It made a big difference on my car, after the headers were installed.

Quoted post

[/b][/quote]
Did you also enlarge the rest of the exhaust? that probably made more diff than the cat.

<!--QuoteBegin--alero-
when i look(ed) under my car, i always saw the O2 bung in the cat. and the O2 sensor went directly into the Cat on the side.....

so i dont under stand how you guys have yours after the cat.....

andways, so if i have an O2 simulator in my downstream, and you guys say Bank 1 is the upstream, why does it say im running too lean in bank 1

Quoted post

[/quote]
That could mean one set of plugs or a coil is bad. or a number of other things.

When GM designed the LA1 and put it in an Alero, they chose to only use 1 upstream O2 sensor that monitors both cylinder banks, but doesn't discern between the two. If you hooked up a scan tool and tried to get a value for the O2 sensor on babk 2, you'd get a big zero....the Alero PCM code doesn't recognize our engines as having a dedicated O2 sensor for each cylinder head. To by having a "Bank 1 lean" code, all you really know is that you're running lean, but you don't know where.
I had this code when I ran a 2.5" supercharger pulley on stock fuel injectors (Eeek!).

[-Alero-]

well knock on wood i think im ok, i just put in a magnaflow cat, and plugged in the normal O2 sensor.

[Satsuriku]

Pardon my ignorance for im not person that knows engines very well (im more of a body person myself) i have no idea what K&N is or what it does

but if i could get a price on one with and without it that would be cool ^_^

[Fast Eddie]

K&N is an air filter company, it filters air to keep big things from getting suked into the engine and causing problems. For a factory drop in replacement should run ~$35.