I know people tune their ecu's to go faster, but is it possible to tune your ecu so that it becomes more efficient? Like more mileage or less pollution

I also remember hearing that rrm's piggyback has increased mileage for a lot of people. someone please enlighten me to how this happens

 

with a simple afc, this is accomplished by leaning out the AFR during open loop mode. most of the fuel savings is from spending less fuel while you're romping on the gas. this also creates better power than stock by having more efficient combustion as the stock fuel maps are conservative from the factory. fuel savings is not made during cruising because emission controls dictate the AFR during this time and adjusts itself to not only burn clean, but make changes to the AFR so the catalytic converter works efficiently. that is why a AF meter will sweep back and forth between lean and rich while you're cruising.

if you have a complete standalone fuel management system and a wideband, AFR during cruise can be open loop and set for something around 16.1:1 for better gas savings. the crappy thing about this is that the weather changes and so there would have to be accomodations. some of the fuel efficient v-tec's will run close to 20:1 and then richen up, and then lean out again. stock AFR during cruise for any car should be around 14.7:1 not only because it's stoich, but it is with range where the catalytic convertor works optimally.

 

wow thanks for the reply. I think i'm gonna forget about headers for now and go straight to rrm's piggyback! Was just curious how a car gets faster and more efficient at the same time