Originally posted by IndyTour:
I am running .86 to .88 at WOT according to Dyno and obd-2 datalogger testing. Will new 19 lbs injectors help correct the lean condition without outside help? Or will the 19lbs work like 17lbs, just having the ability to add fuel? leaving no adjustment?
Maybe, maybe not. The bigger injectors will cause the PCM to learn a large negative Long Term Fuel Trim, meaning that it will shorten the injector pulse width under closed loop conditions. AFAIK, the LT Trim is used as one of the inputs under WOT (but not the O2 sensors) to determine how long to fire the injectors.
That being said, when I went to 24# injectors, I set CELs for Too Rich i.e. LT Fuel Trim too negative. Bill Jenkins did the same when he installed SVT injectors in his Gen 1 Mystique. To get rid of my CEL, I only had to set the AFC below 4000 RPM at part throttle. No CEL so far (about a week). Probably because not too much closed loop driving gets done at 4000+ RPM.
Bottom line, if you want to hunt down that lean problem (and .86 - .88 is something I would be concerned about) by putting in bigger injectors, you are going to need something to control them. You would probably be better off getting that something first, seeing if you can use it by itself to richen up properly, then go for bigger injectors if you still need more fuel up top.
