red90dx

here's the problem :

I have a bog/hesitation, right off idle say 700rpm and reving it up the range...if i reved from 1000 up, its fine...just off idle.

high loads bogg down, like a studder then picks right up...


ENGINE : 01 b20b <---jdm model, its the 9.6:1 usdm b20z.

things ive checked/changed.

main relay
timing w/ gun
crank mark and cams.
valve lash
GAPPED sparkplugs & wires
fuel filter
FUEL PUMP is ok cause my B&M is reading 42 at idle & 53 at WOT
NO VACUUM leaks.
good / newer cat.
injectors were cleaned & balanced, OHM reading OK.
TPS was set .48 and 4.88 WOT

now, at STARTUP & when warm, the two holes in the throttle body are sucking air, .... I didnt think they both should stay open FITV valve anyways.....is this the reason my intake is louder now?

ECU is reprogrammed p75 w/ b20 stock configured maps. OBD1


NEED HELP.....

chris_si98

if it bogs down its running rich. To confirm that read your plugs. Or you could mistake if for an idle issue (fitv or iacv). I know you said you have no vacuum leaks, but what I want to know is how did you check it? Vac. leaks are usually the cause for running rich

imported_plzbeleiveit

plugs are gone maybe?

dingus888

fuel pressure regulator garbage maybe

if it's a real bad problem you pretty much changed everythign I woudl have told you so I am out of ideas iacv maybe.

scott newman

try to pinch off the return fuel line and try it while using a pair of plyers to pinch it. This will tell you if its a fuel problem, if it runs better, its lean if it runs worse its rich, if no change, then somthing else. Is the engine healthy??

imported_Polish_tom

Try checking the O2 sensor i have the same exact problem