My 2010 mustang when I first started modding would run like crap and throw check engine lights. I build engines and can abso
Headers can effect afr and how rich or lean you are running. The computer can only compensate so much. This is why many reputable header manufacturers with state "Tune required" with their headers.
American Racing Headers recommends a tune but states its not necessary.
The reason everyone runs rich at idle and cruse is because O2s work off of heat. No heat = lean.....
O2 sensors measure O2, they only need heat to function properly which is why most are now heated. Them not being hot will only cause the engine to run in closed loop instead of open which is taking data from sensors .
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).
Again, see heated O2 and its the cats needing to be close to the manifolds in order to lite off and get hot.
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.
Again, see heated O2's
O2 sensors very the voltage based upon the O2 content, not heat/temp of the sensor. Using your logic, an engine with headers would always read rich due to O2 location. I have full long tube ARH headers on my Z06, what you describe does not happen.
Also, dumping fuel is used to cool a cylinder, not heat. Lean conditions create heat dumping fuel is used on the C6ZR1 during extreme situations to cool the cats.
The oxygen sensor, otherwise known as the O2 sensor, does what its name suggests – it measures the amount of oxygen in the exhaust. While this may sound like a fairly modest...
www.delphiautoparts.com
O2 sensors can typically be categorized as either a narrow band or wide band sensor. A sensing element sits inside the sensor, encased in a steel housing. Oxygen molecules from the exhaust gas pass through tiny slots or holes in the sensor’s steel shell to reach the sensing element or nernst cell. On the other side of the nernst cell, oxygen from the air outside the exhaust travels down the O2 sensor and makes contact. The difference in the amount of oxygen between that present in the outside air, and that present in the exhaust promotes the flow of oxygen ions and produces voltage.
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."
No you adjust ignition timing and the fuel injector pluse, look at HP tuners. The only thing you can do to an O2 senor is turn the rears off.
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.
No you won't, headers alone will not make you run too lean.
I have been through this kind of stuff many times. For knowledge reference I have a 2010 mustang with a supercharged 326 stoker motor and methanol injection with a return fuel system. I built and installed everything myself and worked with 2 different companies to get the best tune possible for my setup.
I have built Z06 with an N/A ERL 434ci LSX stroker motor, 600 rwhp on 93 and 625 rwhp on e85, 2 tunes, one mass air and one speed density as the cam is a 250/258 @.050. Heated front O2s in ARH 31" long tube headers.
All this aside, headers are not causing the OPs issue and O2 are out even in the equation during a cold start