Headers & air/fuel ratio??
Thread Starter
On The Tree
Joined: Sep 2006
Posts: 102
Likes: 0
From: Missouri
Headers & air/fuel ratio?? i just got a new set of l.t. headers put on along w/ some new O2 sensors.....with these headers will i need to get my car (air/fuel ratio) re-programmed? the car sounds a little starved right now.
yeah i think most people run more rich than lean after an LT install...but no you really don't have to get your car tuned. You can, of course, and make a little more power but I would only get a tune if you make a little bit of bigger mod (like a cam)
Originally Posted by houseylou
i just got a new set of l.t. headers put on along w/ some new O2 sensors.....with these headers will i need to get my car (air/fuel ratio) re-programmed? the car sounds a little starved right now.
Dont listen to all the people that say that Lt's make you run rich, that is pretty much just an Internet myth.
Originally Posted by brad8266
Dont listen to all the people that say that Lt's make you run rich, that is pretty much just an Internet myth.
But in all seriousness, he's right. Your car's PCM will correct for it one way or the other (rich or lean), and it usually won't fall anywhere in the middle. And there's really no way to tell without getting some wideband data.
When I had my car dynoed after my exhaust install, Speed Inc's wideband showed I had an A/F ratio of about 12.5 all the way across the board, as measured at the tail pipe. When I installed my wideband O2 sensor, it was saying it was more like 11.8-ish at WOT, as measured at the header collector. Even widebands don't agree
Originally Posted by brad8266
Well in closed loop(idle and part throttle conditons) the PCm will use the fuel trims to maintain 14.7 AFR no matter what. At WOT though you very well could possibly be lean due to added airflow through the engine without the added airflow being reflected in the MAF and VE tables.
Dont listen to all the people that say that Lt's make you run rich, that is pretty much just an Internet myth.
Dont listen to all the people that say that Lt's make you run rich, that is pretty much just an Internet myth.
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Five Reasons the Camaro Was the Most Pivotal Player in the Pony Car Wars 2.0
Brett Foote
The reason everyone runs rich at idle (VERY BAD) and cruse is because O2s work off of heat. No heat = lean.....
With stock manifolds, the O2s run hotter due to being so close to the exhaust port. As such, they "switch" around a higher voltage and this "switch" voltage is what the computer takes as being the correct area (the computer directly tries to keep the O2s around this voltage).
When you install headers, the O2s move way down the line to the collector (WAY away from the exhaust port). As such, during low flow times (idle and cruse), the O2s run cold. This cold running makes the O2s switch around a lower voltage which the computer takes to mean "not enough fuel." As such, the computer dumps loads of fuel into the mix in order to heat up the exhaust (this fuel is actually burning inside the exhaust) and as such boost the temps.
When you retune, you adjust this "switch voltage" to tell the computer "no....that is indeed the correct voltage to be at when in this cell."
You will run lean at high RPM, you are flowing more air than the MAP/vs./RPM table indicates. The MAF somewhat compensates for this but it is never perfect.
With stock manifolds, the O2s run hotter due to being so close to the exhaust port. As such, they "switch" around a higher voltage and this "switch" voltage is what the computer takes as being the correct area (the computer directly tries to keep the O2s around this voltage).
When you install headers, the O2s move way down the line to the collector (WAY away from the exhaust port). As such, during low flow times (idle and cruse), the O2s run cold. This cold running makes the O2s switch around a lower voltage which the computer takes to mean "not enough fuel." As such, the computer dumps loads of fuel into the mix in order to heat up the exhaust (this fuel is actually burning inside the exhaust) and as such boost the temps.
When you retune, you adjust this "switch voltage" to tell the computer "no....that is indeed the correct voltage to be at when in this cell."
You will run lean at high RPM, you are flowing more air than the MAP/vs./RPM table indicates. The MAF somewhat compensates for this but it is never perfect.
Originally Posted by 2001CamaroGuy
The reason everyone runs rich at idle (VERY BAD) and cruse is because O2s work off of heat. No heat = lean.....
With stock manifolds, the O2s run hotter due to being so close to the exhaust port. As such, they "switch" around a higher voltage and this "switch" voltage is what the computer takes as being the correct area (the computer directly tries to keep the O2s around this voltage).
When you install headers, the O2s move way down the line to the collector (WAY away from the exhaust port). As such, during low flow times (idle and cruse), the O2s run cold. This cold running makes the O2s switch around a lower voltage which the computer takes to mean "not enough fuel." As such, the computer dumps loads of fuel into the mix in order to heat up the exhaust (this fuel is actually burning inside the exhaust) and as such boost the temps.
When you retune, you adjust this "switch voltage" to tell the computer "no....that is indeed the correct voltage to be at when in this cell."
You will run lean at high RPM, you are flowing more air than the MAP/vs./RPM table indicates. The MAF somewhat compensates for this but it is never perfect.
With stock manifolds, the O2s run hotter due to being so close to the exhaust port. As such, they "switch" around a higher voltage and this "switch" voltage is what the computer takes as being the correct area (the computer directly tries to keep the O2s around this voltage).
When you install headers, the O2s move way down the line to the collector (WAY away from the exhaust port). As such, during low flow times (idle and cruse), the O2s run cold. This cold running makes the O2s switch around a lower voltage which the computer takes to mean "not enough fuel." As such, the computer dumps loads of fuel into the mix in order to heat up the exhaust (this fuel is actually burning inside the exhaust) and as such boost the temps.
When you retune, you adjust this "switch voltage" to tell the computer "no....that is indeed the correct voltage to be at when in this cell."
You will run lean at high RPM, you are flowing more air than the MAP/vs./RPM table indicates. The MAF somewhat compensates for this but it is never perfect.
Originally Posted by monicaz28
When I put LT's on my car, it was rich. I'm not going off of the internet, I'm coming from personal, been there, done that experience.
