nj1266

iTrader: (6)

I did not test whether I got better gas mileage or not, but I DEFINITELY got leaner AFR than stoich when cruising or when at Idle. Check the link and you will see the before and after tables of the results.

MalibuJack

iTrader: (5)

Well, understand that putting the car in a situation where the trims out of range, means it won't adjust for varying conditions.. Thats why its not the right way to do that..

Kyle_Y

sorry .. missed this thread for some reason (on purpose maybe )

MJ, yes joy in sharing .. but like you I don't really see the point in altering the close loop mapping and you're liable to damage the engine easier if you modify that (yep, I got cruise knocks when I was meddling with the close loops which is quite bad)

What I ended up doing was I modified the open loop map and ran totally in open loop once I'm off idle

I figure that since the volkswagon and some other high tech cars are using WBO2 to run in open loop all the time as stock , why can't I do the same with my WB ??

its a PITA as I have to map the entire map from low rpm high load regions to high rpms high load regions very CAREFULLY .. not to mention transition loads!!

I cruise on the highway around 15-16 AFR with a slight gain in MPG with this setup..

and since I'm in open loop most of the time .. my fuel trims are always very close to 0%

MalibuJack

iTrader: (5)

If you have the info, you should post it anyway. Most people want to figure it out for themselves on whether or not its worthwhile. Going from 14.7 to 15.0 or so netted no real gains whatsoever on my car. And forcing open loop all the time essentially turns your EFI into one big programmable carburetor that is incapable of adapting to changing weather and other conditions.. Its a catch22 no matter how you look at it.

MalibuJack

iTrader: (5)

And I think you have it backwards, some Volkswagon, Porsche and other cars are using wbo2 sensors to run closed loop feedback all the time, using target AFR and cylinder pressure detection and active detonation algorithms for timing to always run closed loop regardless of engine load. Unfortunately it can be a double edged... Its really something all ECU's should have always done, but its only in the past 10 years have PCM/ECM technology advanced to the point where their fast and reliable enough to do that.

I am working on installing an aftermarket EFI system on my supercharged malibu that is capable of Lambda control, but it still uses timing maps though that can be added on to with a failsafe device.

MalibuJack

iTrader: (5)

Oh and before someone mentions automapping/auto-tuning ECU's like the Autronic.. That is a tuning method and not a closed loop control, it is a mode that uses wideband signal to read AFR and meet a target, then updates the maps accordingly, you still end up with maps and open loop fuel control under load.