Lexus IS Forum banner
1 - 13 of 13 Posts

·
Registered
Joined
·
884 Posts
Discussion Starter · #1 ·
i understand that casper's electronics is making the xerd 02 sim. and some months back i remember a few members discussing the sims they bought from caspers. thinking i may soon need sims, i called to ask a few questions--

btw, as per caspers, we will have a set of IS300 specific sims available around jan 1, and they will be $98 for the set.

my question:
caspers told me that it was a VERY bad idea to run a header/mid-pipe with no sims (as we all know) it causes the CEL light to come on.
they said this is bad because the ecu freaks with the cel on, and tries to fix it by running rich. this of course will carbonize the exhaust, foul spark plugs, etc.

has anybody had any adverse effects from the CEL beyond being annoying.

and this also would mean that tuning an afr with the cel on is useless becasue the car is running richer than it will once the sims are in, yes?
 

·
Podiatrist
Joined
·
22,260 Posts
I don't think that's the case...but someone prove me wrong.

My understanding of it was that the sensor 2's only tested to see if the CAT was working. The Sensor 1's are the ones that the car uses for fuel adjustment.
 

·
Guru of Supercharged ISs
Joined
·
6,620 Posts
ummmm yeah ... it is just the headers that throw CE lights w no O2 sim....


I have been running mine for several months now : XERD header ... NO o2 sim .. o' course! :x

...I seem to have no really noticeable adverse effects generally but my car does seem a bit less punchy now as it was at first... kinda makes me think something more is going on there than just the system letting you know there is a bad cat.....

I too have been worrying about running it for extended periods of time with NO O2 sim & i am curious as to what the OBS system is doing with the readings like this...


I too have held off on dyno tuning the SafcII as i assumed withthe CE light on, there might be some anomalies in the readings the system gets & the "rich" condition that the O2 sensor/CE light produces...? so the dyno tuning might niot "stick" or be as properly set as if the car was running w NO CE light during the tuning...? i might be WYA off here but thats what i thot so i have been waiting to getthe O2 sim installed & get rid of the CE light & THEN dyno tune....


edG
 

·
Threadlocker
Joined
·
7,912 Posts
running rich will kill a catalytic converter pronto (but who cares, you have a header/y-pipe)... i'm sure there are adverse effects on your exhaust as well.
 

·
Mr. Negative
Joined
·
11,977 Posts
This is completely correct. Only the primary sensors affect fuel. The secondary are just tree huggin' o2 sensors.

SophieSleeps said:
I don't think that's the case...but someone prove me wrong.

My understanding of it was that the sensor 2's only tested to see if the CAT was working. The Sensor 1's are the ones that the car uses for fuel adjustment.
 

·
Registered
Joined
·
884 Posts
Discussion Starter · #8 ·
so the consensus is that casper's was wrong, and that installing a header/y-pipe with no 02 sims WILL throw a cel BUT WILL NOT harm the engine and/or have any adverse lasting side effects?

the car DOES NOT run rich via input from header sensors?
 

·
Mr. Negative
Joined
·
11,977 Posts
I corrected your post. ;) It's correct now.

remember only Bank1Sensor1 and Bank2Sensor1 control a/f ratios.

MSM MT IS300 said:
installing a header/y-pipe with no 02 sims WILL throw a cel BUT WILL NOT harm the engine and/or have any adverse lasting side effects?

the car DOES NOT run rich via input from the secondary o2 header sensors?
 

·
Registered
Joined
·
884 Posts
Discussion Starter · #10 ·
somebody start from the beginning:

how many sensors are there on our car and where are they?

i thought we had 3:
1--on the intake
2--on 3 of the 6 header pipes after a cat
3--on the other 3 of the 6 pipes after the other cat
(and noumber 2 & 3 are where the sims would go to fool the car into thinking it still has cats)


obviously i am wrong--someone please correct me in laymen's terms...
 

·
Mr. Negative
Joined
·
11,977 Posts
there are 4 o2 sensors. 2 on the first bank(aka cylinders 1,2,3) and 2 on the second bank(cylinder 4,5,6). The first o2 sensor on both banks(aka: B1S1 and B2S1) are the ones that control the whole thing and control closed loop fuel operations. The second o2 sensors(aka:B1S2 and B2S2) monitor the catalytic convertor effeciency.

The S1's are before the cat on both banks on the stock header. The B1S2 is after the cat on that bank and the B2S2 is the one that's halfway back on the midpipe.


MSM MT IS300 said:
somebody start from the beginning:

how many sensors are there on our car and where are they?

i thought we had 3:
1--on the intake
2--on 3 of the 6 header pipes after a cat
3--on the other 3 of the 6 pipes after the other cat
(and noumber 2 & 3 are where the sims would go to fool the car into thinking it still has cats)


obviously i am wrong--someone please correct me in laymen's terms...
 

·
Registered
Joined
·
884 Posts
Discussion Starter · #12 ·
IS_Dude said:
there are 4 o2 sensors. 2 on the first bank(aka cylinders 1,2,3) and 2 on the second bank(cylinder 4,5,6). The first o2 sensor on both banks(aka: B1S1 and B2S1) are the ones that control the whole thing and control closed loop fuel operations. The second o2 sensors(aka:B1S2 and B2S2) monitor the catalytic convertor effeciency.

The S1's are before the cat on both banks on the stock header. The B1S2 is after the cat on that bank and the B2S2 is the one that's halfway back on the midpipe.


MSM MT IS300 said:
somebody start from the beginning:

how many sensors are there on our car and where are they?

i thought we had 3:
1--on the intake
2--on 3 of the 6 header pipes after a cat
3--on the other 3 of the 6 pipes after the other cat
(and noumber 2 & 3 are where the sims would go to fool the car into thinking it still has cats)


obviously i am wrong--someone please correct me in laymen's terms...
and so that means:
if you buy a header and midpipe, you KEEP the TWO stock 02 sensors BEFORE the cats (because they would not be effected but a header mod) and jack into the LAST two 02 sensors (with 02 sims) because if not the car would freak when it thought the cats had failed?

yes?

so now back to my question (assuming what i just reiterated is correct), is not having sims with a header/y-pipe set up bad?
 

·
Twisties Addict
Joined
·
12,063 Posts
MSM MT IS300 said:
IS_Dude said:
there are 4 o2 sensors. 2 on the first bank(aka cylinders 1,2,3) and 2 on the second bank(cylinder 4,5,6). The first o2 sensor on both banks(aka: B1S1 and B2S1) are the ones that control the whole thing and control closed loop fuel operations. The second o2 sensors(aka:B1S2 and B2S2) monitor the catalytic convertor effeciency.

The S1's are before the cat on both banks on the stock header. The B1S2 is after the cat on that bank and the B2S2 is the one that's halfway back on the midpipe.


MSM MT IS300 said:
somebody start from the beginning:

how many sensors are there on our car and where are they?

i thought we had 3:
1--on the intake
2--on 3 of the 6 header pipes after a cat
3--on the other 3 of the 6 pipes after the other cat
(and noumber 2 & 3 are where the sims would go to fool the car into thinking it still has cats)


obviously i am wrong--someone please correct me in laymen's terms...
and so that means:
if you buy a header and midpipe, you KEEP the TWO stock 02 sensors BEFORE the cats (because they would not be effected but a header mod) and jack into the LAST two 02 sensors (with 02 sims) because if not the car would freak when it thought the cats had failed?

yes?

so now back to my question (assuming what i just reiterated is correct), is not having sims with a header/y-pipe set up bad?

you had it right until the end....the only thing that is triggering the CEL is the B1s2 and b2s2( those of which read for cats) so NO according to these guys it doesnt hurt the performance of the car!
 
1 - 13 of 13 Posts
Top