I had my car tuned with my old kit which was choking the motor, resulting in a ton of back pressure/egt's.. Tuner said he was throwing a ton of fuel at it to get proper afr's because of the BP/egt's.. I looked in the commanded afr table which was 11.2 locked in open loop.. Im not looking to slice and dice the tune but rather the changes..
I changed to a very well flowing t6 kit and now my afr's were 12.2 steady.. Im not sure if it ever was at 11.2, but I figured since this new kit is flowing way better it would have been richer right off jump street. Am I thinking right? OR is it since its flowing better, the af charge is flowing right out?

 

When you make more power...you use more fuel. If you don't have it configured in closed loop...it's going to run leaner because it's usiing the "old fuel values" with more airflow.

 

and that holds true even tho it is still on 15psi? gen7...

its the exhaust side that's flowing better, not the intake side.. and again car was tuned on 15psi on the old kit and just did a pass on 15psi w the new kit..

 

Yes, it's still a simple airpump. 15psi isnt a measure of airflow through the engine...only the pressure ahead of it. If you left the compressor the same and just swapped exhaust side....it would need to spin harder to maintain the same pressure now that the restriction has been reduced.

Aside from the increased airflow at full boost...the tune isn't going to be ideal in the lower portiions where boost comes on. Your boost curve has changed meaning different portion of the map is being used to fuel/time the engine.

 

Ok, that makes a tone of sense now that you explained it that way.. and it was leaner on spoolup as well..

btw, I know of you from the njr board.. just realized your name/location.. im singletgt there..

 

i don't know if your referring to the stock ford fuel injector but in that regard the information within this thread couldn't be any furthur from the truth

ford ecu's for the most part are mass air, as long as your not fuel system is up to par and your not maxing out the injectors or the maf, your
AFR should remain the same, I've tuned numerous cars @ 5psi or so and folks then later turn the boost up to 20-25lbs and the AFR remains constant at 11.5

there's only a handful of dyno tuners like myself that actually know how to adjust these ecu's to do exactly what we want, for example after i tune a boosted car if you take the boost off for any reason you won't be overfueling in the 11s your AFR without boost will now be in the 12s and you won't be under advanced either as i set my timing appropriately, all depends on the tuner and how much they know

 

this is a gen 7 efi he's running, not a maf system. So id be safe to assume, uh your incorrect. sometimes reading a little more deeper into the thread these things get noticed, cuz I miss this shit all the time.lol. speed density will get leaner with a more free exhaust and no other changes. The combustion chamber will be cooler with less back pressure. So timing will need to be adjusted accordingly as well. Time for a re tune.