i have a header intake and exhaust and msd cap,coil,wires,sci box and ngk platnuim laser cut plugs i need to know if yall would recomend turning up my fuel presure on a b16 if so how much its on 41 now any help would be great thanx

 

oh yea i have a vafc to if that will help

 

highly doubtfull you need to turn the fuel pressure up with what you have. i have cams, higher compression pistons, removed balance shafts a ton of bolt on's etc and i had to lean my vafc out almost 8% the whole way get to a nice 13-13.5 a/f ratio. granted its on an h22 but almost every vtec motor i have seen runs rich. before leaning out imy a/f was in the high 11's with all that crap

best bet, go to a dyno and let the truth be told

 

on my vafc i got all the fuel +4or+5 in high and low cam my car would not crank -4or -5 and ure at -8

 

depending on what obd you have you really have to watch adding fuel with the vafc. in obd1 and 2 cars it does really bizzare things to the long term fuel trim. adjusting anything in the low throttle on the high lobe or low lobe does absolutly nothing but mess up the long term fuel trim. your altering the short term fuel trim but the ecu brings it right back to stoich and in the process the data the ecu uses to calculate LTFT gets garbbled and ends up throwing the LTFT out of wack. out of curiosity i put it to the test and made some adjustments to the low throttle section of the vafc and within seconds the ecu corrected my a/f ratio back to bouncing between 14.5 and 15.0. not only did it correct my low throttle a/f ratio back to stoich it screwed with my ltft settings so i had to pull more fuel to achieve the same a/f ratio at high throttle then i had to before messing with low throttle.

seems that the only thing a vafc is good for on an obd1 or 2 car is tuning WOT. which is not all bad since the ecu does a damn good job at keeping partial throttle fueling fairly stoich. granted stoich isnt the best a/f ratio to have for making power but its better then 16:1 etc... the only problem i have encountered is finding the point where the ecu switched from closed to open loop mode. a couple people have said its at 33% throttle but i dont think so since at 33% my wideband is telling me the ecu is still keeping things stoich. i suspect it's somewhere closer to 40-50% throttle

and yeah i just saw your name said crx and you have a b16 so you probably have white plug obd0 motor and absolutly nothing i just typed would pertain to you anyway so im gonna shut up and leave now.

but i still cant understand why you would need to add fuel with what you have. a club i hung out with back in pittsburgh had 4 crx's all with obd0 b16's with pretty much all the bolt ons you can get and they didnt need to add fuel at all... if your motor wont crank unless there is fuel added on the vafc i would almost say its timing related not fuel related. remember when you add or subtract fuel with the vafc your fooling the car into referncing a totally different cell for fuel and timing then it should be seeing. maybe by adding fuel you are changing the timing from where it was to the point it needs to be for the car to start. all motors are different i guess. like i said before your best bet is to hit the dyno, thats where your best advice is gonna come from