For the past few weeks my "narrowband" a/f ratio has been bothering me below 2500 rpm. Whenever I get in openLoop below 2500 my a/f is really lean. How lean? No clue. All I know is my narrowband gives me the leanest reading possible. How much fuel should I add below 2500rpm?

 

At 2.5k rpm my car was over 15AFR. 2.8k rpm 14AFR.

 

Yeah, but I'm wondering about below 2500. And 15:1 at WOT is kinda lean if you ask me.

 

I really don't think you can change anything because that is mostly your cruising rpm. Your ECU will compensate STFT and LTFT anyway.

 

Piggyback kicks in when in openLoop isn't it?

I would be shooting for something like this:

 

I wouldnt really worry about it. Even if you are turbo, you arent hitting any kind of boost that low, you are still in vaccum and unless you have changed any fuel curves before, this is what the stock maps are giving you, so why mess with a map that you know mitsubishi designed themselves? If it was really that damaging i would crap my pants to find out mitsu did it intentionally. IMO its not that big of a deal, if you watch your narrowband you should also be running extremely lean at like 10 percent throttle when you go into open loop above 3k rpms, once again, its the way its been since the factory so i wouldnt really worry about it too much, theres not enough pressure or crazyness going on inside the engine at those times to do any damage anyway.

 

I'm not worried about damage. I'm worried about performance. Running too rich affects performance, so does running to lean. I've got no datalog to back me up, but according to what I see(narrowband, and vaccum), Mitsu starts dumping fuel above 2300 rpm. That currently where the piggy kicks in and removes some of it. If could get the piggy to add some fuel where Mitsu went lean, I think I could achieve a smoother power curve. I could possibly start getting some kick around 2000rpm instead of 2500. At least... that's what I think but I'm very open to anyone's opinion on that matter.

 

Also i wouldnt watch the narrow too much when it comes to the extremes. Its called narrowband because its just that, it only monitors a narrow band of numbers and rounds the rest up or down. So when you are pegged super lean you may not be as lean as you think, or the opposite, being pegged super rich may not be that rich. Like everyone always says on the board, ditch the narrowband before you do any tuning, the only thing the narrowband is really good for is just to give you a general idea if you are going to explode or not. its good if you are running a turbo kit with a piggy thats preprogrammed or a kit that isnt looking to dial in on exact numbers. I've got a narrowband for now to just keep a general eye on things in between the final install of the turbo and working out all the kinks, once i have everything running and set up right then i will be moving to the wideband and tuning properly. Baby steps

 

You will chase narrowband around too much. Wideband is only correct way to tune. As for lean condition below 2500, that is not end of world. Cars idle around 15to1. That is normal. Regardless, get a wideband for sure.

ROAD/RACE