Headers and Tune??

[5GSS]

Originally Posted by Bee

But I'm also pretty sure that the way most tuners will get around the CEL with LT's is by shutting off the rear O2 sensor. This tells me that the car is not relying solely (if at all) on the difference between the O2 sensors to adjust the A/F ratio.

That is correct. MAF measures air mass going in, first O2 sensor measures O2 coming out (to calculate A/F), second O2 sensor measures O2 after cat (to verify properly functioning cat).

[brantley847]

Originally Posted by Bad70supreme

You will be fine chillout man! A tune is not NEEDED, I have been told this by a few vendors... everyone knows your getting your full bang for the buck, and your car will run better with... but you are not going to blow your engine driving to the tune shop 90miles

Note to self: Send bill to bad70supreme

....good to go. hahah, I kid..I kid

[Drago77]

Good thread guys... im working my way toward headers as well- very informative!

[SSiick]

Originally Posted by 5GSS

That is correct. MAF measures air mass going in, first O2 sensor measures O2 coming out (to calculate A/F), second O2 sensor measures O2 after cat (to verify properly functioning cat).

This is what I had always thought. So to sum it all up, if you do LT's without a tune it will not have ANY affect on your A/F ratio as the first set of O2's is what determines that. The second set of O2 sensors are strictly to determine if your cats are functioning properly. If they are not or the second set of sensors is missing, the car will throw a code. The code however will still not affect your A/F ratio. This was the big change with OBDII computers which allowed for emissions to be tested without the use of the sniffer.

Guys that are worried about blowing up their motor because of not getting a tune need not worried. Look at how many people have added LT's to 4th gens and not tuned them.

[ArmoSS]

Lots of great information...I just need to find a shop that'll know what to do with all of this stuff, since half of the things written here is greek to me...not as much of a guru as some of you guys out there, but I definitely appreciate the input.

Originally Posted by SSiick

This is what I had always thought. So to sum it all up, if you do LT's without a tune it will not have ANY affect on your A/F ratio as the first set of O2's is what determines that. The second set of O2 sensors are strictly to determine if your cats are functioning properly. If they are not or the second set of sensors is missing, the car will throw a code. The code however will still not affect your A/F ratio. This was the big change with OBDII computers which allowed for emissions to be tested without the use of the sniffer.

Guys that are worried about blowing up their motor because of not getting a tune need not worried. Look at how many people have added LT's to 4th gens and not tuned them.

SSiick, I read that it was "easier" to have LTs with 4th Gen with no tune since they weren't as "sensitive" as 5th Gen.