I know the pcm tries to keep it at 14.7. It does this to reduce emissions not that it is the best ratio for fuel economy or performance (open loop is much more important to performance I'll be running 13:1 there).

My question is (without running widebands) is there a way to have the car run leaner than 14.7 in closed loop (like tricking the computer/ tuning etc.)??

 

Problem is the O2s are accurate ONLY at that 14.7. You CAN make it run at a different AFR BUT you need to know what you are doing and need a wideband to monitor it at least during tuning. Rumor has it there are lean highway cruise tables in the pcm accessible if you get into hex editting. That is about all I know about it though. I know it exists and a little of what it can do but don't know how to get into it yet.

 

Why do you want it different than 14.7 under light load? Runs pretty damn efficiently there.

Rich

 

Just want it a little more efficient

 

yeah I was reading about those myself today in another post. I wonder if that would be safe off the highway? thanks for the help and if you find out anything please let me know.