bonesx0x2x4x

sup guys i got a 98 gs-r b18c1 and i think im maxing out my inectors...

i got the victor x intake mani and i was informed the one a stock )p72) ecu with stock injectors i should be fine...

upon start up the engine idles fine at 1500 for about 3 mins then slowly goes down to about 1200 rmps then bogs down to 200rpms for about 10 seconds revs back up and idles at 700

my short term fuel trim percentage is goins nuts....starting at 0% going all the way up to about 46.9% holding for about 10 seconds and then droppping back down resetting and starting over again

it throws a lean code (p0172) and no its not the o2 sensors because theyre actually reading lean

SOOOOOOOOO i was wondering are their any injectors i can get that run off the stock ecu but are biigger to compensate for the air flow i have so i can pass inspetion?

any help is great

thanks

el crapitan

o2 sensors will read lean if they are becoming contaminated

bonesx0x2x4x

i understand that....before i rebuilt it iw as driving it in the winter and sucked in some water and thats when the whole problem started...i figured it was a vacuum leak when it first started happeneing before i took it apart but now i know the vaccuum is good so you think that the water cou;ldve actually made it all the wat through the engine and hit the o2 sensor?

donut.

You probably need some 1000cc injectors bro

racebum

o2 sounds like it took a ****. if you have a stock engine and stock injectors you either have failing injector{s} or a bad o2

stock 240cc injectors are cheap and so is the primary o2, you can replace all of it for around $100

the ST fuel trim going THAT lean is dangerous though, you shouldn't drive the car until you fix the situation

bonesx0x2x4x

Yeah bro cause my 180hp teg needs 1000 injectors and they'll deff work on my stOck tune...

Thanks for the help

bonesx0x2x4x

Yeah that's wut I'm thinking....nice to see some actual intelligence on here

el crapitan

fuel/high hydrocarbons contaminate an o2 sensor usually. running rich will do it.
but if the o2 sensor became contaminated, you have to ask yourself why it did. otherwise, just replacing it solves the result of the problem. but not the problem

Dogginator

You will most likely have idling issues with larger injectors on a stock OBDII ECU. Do they still make fuel pressure risers?

1998GsRIntegra

240cc/min on a teg and most honda motors.

Dogginator

You are correct.

thewrai6th

p0172 is rich, not lean. You do not need larger injectors either.

Only the primary O2 sensor adjusts for fuel trim. If the sensor gives a biased reading, then the ECU compensates by adding or reducing fuel.

If the sensor is biased lean, then the ECU will start adding fuel until it throws the p0171 code.
If the sensor is biased rich, it will reduce the fuel until it throws a p0172.

If you are running 240cc, and you say your fuel trim was +, not -, it must be dumping gas in like crazy and you are likely running extremely rich.

racebum

good catch on the code.

similar fix though. if the ecu is just pulsing the **** out of the injectors it's either getting the signal to do so from the o2 or you have a leaking injector or two that's dumping in constant gas and causing a rich condition in the exhaust. actually, wait a minute, if the injectors were going mad the ecu would be reducing fuel causing a - st trim and a positive long trim.

this sounds more and more like a glazed o2 and or a car with bad plugs-cap-rotor, the ignition components usually cause a hunting idle though

bonesx0x2x4x

Upstream o2 sensor...problem fixed...thanks guys