Long tube headers, the rear O2's, and CEL question

[FNBADAZ06]

I'm seriously considering installing the B&B longtube headers I have in the coming weeks, which will then delete the rear O2 sensors that are down stream from the cat's. I know that these O2's are used for cat effiency monitoring only, and if I remove them I'll have to tune them out or get a CEL. I'm planning on purchasing HP Tuners Pro over the holidays and feel comfortable in being able to use the application to turn off the O2 monitoring and cat test (with a little help from the tuning gods ). Question is, with the CEL light lit during the period before I can turn off the rear O2's in the ECU, will this in any way cause the ECU to reduce power to the engine ? Also, is there any data/logging anyone has done on a stock LS7 with just headers (minus cats) to see if the longtubes lean out the AFR at any significant level that I should be alarmed about, which would require an expedite on a "full" tune ?

[Two Fangs]

As long as the car just throws catalyst efficiency codes, you will be fine. You can keep an eye on a possible lean condition by monitoring your fuel trims. If you see the trims adding fuel, you know you are getting a tick lean. Most likely, with a stock cam, this will be a non-issue.

[FNBADAZ06]

As long as the car just throws catalyst efficiency codes, you will be fine. You can keep an eye on a possible lean condition by monitoring your fuel trims. If you see the trims adding fuel, you know you are getting a tick lean. Most likely, with a stock cam, this will be a non-issue.

Thanks, Mr.Parker If I see anything less than +10 on the trims you think I'll be OK ?

Is there an indirect way (or maybe a direct way) of knowing what the AFR is by looking at the narrow band O2 sensor data....it looks like it's displayed in millivolts in the default gauge screen in HP Tuners ?

[NicD]

Rear O2 and cat codes are non-performance codes, it will not affect how the car runs it will just be annoying seeing that check engine light. The fuel trims will do their job and it should not run lean. Looking at the factory O2 millivolts is not going to give you any information to go off of other than a generic it has fuel above stoich. They are not accurate anywhere outside of the very small window around 14.7 but generally over 850 mv is normal WOT fueling.

[FNBADAZ06]

Rear O2 and cat codes are non-performance codes, it will not affect how the car runs it will just be annoying seeing that check engine light. The fuel trims will do their job and it should not run lean. Looking at the factory O2 millivolts is not going to give you any information to go off of other than a generic it has fuel above stoich. They are not accurate anywhere outside of the very small window around 14.7 but generally over 850 mv is normal WOT fueling.

Thanks, Nic. Based on the limited info that monitoring the O2's is giving me, should I be watching/logging a more pertinent piece of data in lieu O2 readings in the default HP Tuners gauge screen ?

[Two Fangs]

Besides monitoring B1S1 and B2S2 volts, log LTFTs and STFTs. I usually build bar gauges for all of these... Nic may have things that he looks at as well, but these work well for me...

[FNBADAZ06]

Besides monitoring B1S1 and B2S2 volts, log LTFTs and STFTs. I usually build bar gauges for all of these...

Nic may have things that he looks at as well, but these work well for me...

I think the default gauge config includes the LTFT and STFT for both banks. You think I should replace the O2 monitoring with something else with more value ?

[Two Fangs]

In your N/A stock aplication? No, I think the defaults are probably OK, may want to watch actual throttle position and commanded throttle position, that can be telling.

[Jon]

Telling of what? Would putting headers on a car without tuning benefit me at all? I'm looking at the 1 3/4 or 1 7/8 LG Pro headers.

[Two Fangs]

It can be interesting to monitor how much throttle the car actually receives, versus what the driver commands. More interesting is how a change in the way the car is driven can seem to affect it. As far as headers, I have not seen appreciable gains with headers on an otherwise stock LS platform.

[HOXXOH]

I'm seriously considering installing the B&B longtube headers I have in the coming weeks, which will then delete the rear O2 sensors that are down stream from the cat's. I know that these O2's are used for cat effiency monitoring only, and if I remove them I'll have to tune them out or get a CEL. I'm planning on purchasing HP Tuners Pro over the holidays and feel comfortable in being able to use the application to turn off the O2 monitoring and cat test (with a little help from the tuning gods ).

Question is, with the CEL light lit during the period before I can turn off the rear O2's in the ECU, will this in any way cause the ECU to reduce power to the engine ?

Also, is there any data/logging anyone has done on a stock LS7 with just headers (minus cats) to see if the longtubes lean out the AFR at any significant level that I should be alarmed about, which would require an expedite on a "full" tune ?

Be sure you have a bung for a wideband prior to the install. If there's not already one there, then when you put one in, make sure it's easy to access.

[FNBADAZ06]

I'm seriously considering installing the B&B longtube headers I have in the coming weeks, which will then delete the rear O2 sensors that are down stream from the cat's. I know that these O2's are used for cat effiency monitoring only, and if I remove them I'll have to tune them out or get a CEL. I'm planning on purchasing HP Tuners Pro over the holidays and feel comfortable in being able to use the application to turn off the O2 monitoring and cat test (with a little help from the tuning gods ).

Question is, with the CEL light lit during the period before I can turn off the rear O2's in the ECU, will this in any way cause the ECU to reduce power to the engine ?

Also, is there any data/logging anyone has done on a stock LS7 with just headers (minus cats) to see if the longtubes lean out the AFR at any significant level that I should be alarmed about, which would require an expedite on a "full" tune ?

Be sure you have a bung for a wideband prior to the install. If there's not already one there, then when you put one in, make sure it's easy to access.

[Jon]

You need to update your best ET.

[FNBADAZ06]

You need to update your best ET.

LOL....done.

[c6-na-killa]

I have A ls2 c6 mn6 lg pros 1 3/4 lg cats varam intake n corsa sport n no tune yet or engine lights that combination makes a big diffrence over stock who ever says otherwise is crazy with out a tune my dyno numbers might not be that much higher but damn do i feel that torgue n hp increases dont really wana spend money on a tune till i cam my vette

[ChadC]

I have A ls2 c6 mn6 lg pros 1 3/4 lg cats varam intake n corsa sport n no tune yet or engine lights that combination makes a big diffrence over stock who ever says otherwise is crazy with out a tune my dyno numbers might not be that much higher but damn do i feel that torgue n hp increases dont really wana spend money on a tune till i cam my vette

How about spending money on punctuation marks?