Lexus IS Forum banner
1 - 11 of 11 Posts

·
Registered
Joined
·
7,294 Posts
Discussion Starter · #1 ·
Is it possible? I know this O2 sensor crap bite us in the azz, so thats why I am asking.

Possible to run no cats just a pure 3" straight pipe and use 1 O2 sensor and possibly a O2 simulator to successfully run without any CEL or OBD codes?
 

·
Registered
Joined
·
1,796 Posts
good question?

too bad i dont know jack :lol:

bet your exhaust would sound killer though :eek:
 

·
Mr. Negative
Joined
·
11,977 Posts
the rear o2 sensors only trigger the "Catalyst System Efficiency Below Threshold" errors. The sensor 2's don't control drivability and fuel trims, as those are controled by the better sensor 1's.

If you correctly simulate the sensor's you should be able to get away without a cat without a problem, I believe. someone correct me if that is incorrect though.

With all that being said it's a fairly minor CEL that not many people care about. the 0420 and 0430 that is. And on the other side a HIGH quality RandomTech 3" high flow turbo cat isn't going to cause much problem. It will also kill the drone from the car.
 

·
Registered
Joined
·
634 Posts
maxxpsi said:
IS_DUDE is correct. That is the set up in my lexus.

Derek
I don't mean to threadjack but I notice how you're boosted and running a rps cltuch. I'm guessing that you still have the stock w55 tranny. Any problems w/ your tranny? How many psi are you running and how long (miles) have you been boosted for? Thanks!
 

·
Premium Member
Joined
·
2,458 Posts
No meow meow. CEL can be eliminated with 02Sim. As ISdude mentioned, just make sure your #1 O2 sensor is good, the rest..no biggy. Oh and the car does sound :pissed: with no cats and more power.
 

·
Penetration Specialist
Joined
·
22,782 Posts
No cats or CEL here. 8)

Sounds mean as hell and spools up a little faster too compared to Doublins.
 

·
Registered
Joined
·
7,294 Posts
Discussion Starter · #9 ·
Erik, Charles.... So if i understand this correctly... o2#1 remains connected. and the remaining two o2 sensors get the simulators?

How does the simulators know what o2 sensor is which and how does it know to give a different reading to the rear o2 sensor behind the last cat?

I mean whats to stop the simulators from ALL broadcasting a .4 voltage reading for example? What makes them give the proper readings?

Im trying to understand this thing thoroughly. Thanks for your help so far.

Charles we may just have to jack up ur car in my garage and take some pics to satisfy me :lol:
 

·
Registered
Joined
·
1,610 Posts
i have the 6speed in my garage. I want to see how far i can push the stock tranny. I'm boosting to 15lbs. Anymore than that i can't keep traction. My car sounds so sick, you will shoot flames from time to time if you declerate then jump on the gas. We are retuning my car today on the dyno. My top end fuel mapp is a tiny bit rich.

Derek
 

·
Registered
Joined
·
4,996 Posts
The way the stock ECU works it expects to see similar signals from the first and second o2 sensors in a bank. The signal however should be delay by the cat. If the ECU doesnt see a delay or the right delay it throws a CE due the CAT not working optimally.

If you looking at the graph (voltage) of the first and second o2 sensors there similar the second one is just delayed a bit and smoother.

Not sure if that makes sense.
 
1 - 11 of 11 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top