i have a h22 ported head, s2 pro 2 cams, ported intake manifold running e85 neptune RTP rc 550 stock block

a/f fine and tunable untill vtec hits. then it starts running lean. if you add fuel it makes hardly a difference and when you add alot of fuel its barely noticable in the a/f but fuel pressure drops.

i feel it some kind of fuel problem becasue i am also running nitrous wet kit. with out bottle and spraying just fuel the a/f get richer

does anyone have any ideas to what the problem maybe?

this is what i have done to try solve the problem
new fuel pump
new fuel pressure regulator
switched from big wire fuel pump to stock and back
checked voltage to the fuel pump after vtec and no change
checked valve lash and was good
checked all grounds
unpinned every ecu pin that i am not using
took all fuses out that i am not using
checked for vacuum leaks and fixed one
sent injectors back to rc and were clean and tested fine
switched ecus
leakdown and compression test
and there are probably more that i cant think of right now

i have spent numerous hours and tons of money and dyno time trying to fugure out the problem. any input would be appreciated and tried untill i have exhausted any and every option out there





Modified by JDM_COUPE at 8:06 PM 2/29/2008

 

do you happen to have a graph of the a/f?

 

no i dont right now. i can get one by tomorrow from the dyno


edit**i actually found one. its my first tune. ill post up in a minute. scanning right now


Modified by JDM_COUPE at 6:32 AM 2/28/2008

 

i was running a big wire for my fuel pump and the alt started taking a ****. the voltage would drop to 11.9 volts. this is after a changed my alt and went back to stock voltage to the fuel pump. this is the original tune i had loaded after i changed the alt. no tuning involved just loaded. if you need another graph with something specific let me know. 5 days on the dyno so i can get you different graphs where i tried different things



i edieted first post. i am running nitrous and the a/f get richer when i spray just fuel from the nozzle

 

What injectors are you running ?
Are you running a fuel pressure gauge ?
What are you running for a distributor/ignition system ?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mtber &raquo;</TD></TR><TR><TD CLASS="quote">What injectors are you running ?
Are you running a fuel pressure gauge ?
What are you running for a distributor/ignition system ?
</TD></TR></TABLE>

im running rc 550 with a resistor box. the first tune they were in 50% duty cycle

yes im running a fuel pressure gauge

OEM honda ignition system

 

everything in neptune was setup correctly? did you "upload calibration"?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98vtec &raquo;</TD></TR><TR><TD CLASS="quote">everything in neptune was setup correctly? did you "upload calibration"?</TD></TR></TABLE>

yes everything to my knowledge is set up correctly. everything was running perfect untill the alternator starting taking a **** by loosing voltage at higher RPM running lean up top.

but i changed the alternator and stop running the big wire and still the same thing happens. voltage still dropps1 volt but not 3 volts as it did before.

yes i uploaded calibration. at first after i changed everything i never touched the ecu untill it kept doing it i uploaded the original map from my tuner and started to toy with it from there, but no changes in a/f

 

Did you change your fuel filter? Where are you taking your fuel pressure readings from? The rail or the filter?

 

What does the fuel pressure do during a dyno pull when the problem is occuring?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 00Red_SiR &raquo;</TD></TR><TR><TD CLASS="quote">Did you change your fuel filter? Where are you taking your fuel pressure readings from? The rail or the filter?</TD></TR></TABLE>

from the filter

changing my filter tonight

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by servion &raquo;</TD></TR><TR><TD CLASS="quote">What does the fuel pressure do during a dyno pull when the problem is occuring?</TD></TR></TABLE>
at first is does nothing. but whe you start adding fuel, i mean alot of fuel the pressue drops alot.

 

what fuel pump you have in there..?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by onepoint6i &raquo;</TD></TR><TR><TD CLASS="quote">what fuel pump you have in there..?</TD></TR></TABLE>

warlboro 255

 

So when you used your old tuneup that was good before these fuel problems, the fuel pressure holds steady at WOT throughtout the dyno run?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by servion &raquo;</TD></TR><TR><TD CLASS="quote">So when you used your old tuneup that was good before these fuel problems, the fuel pressure holds steady at WOT throughtout the dyno run?</TD></TR></TABLE>

yes it holds steady but runs lean.

when trying to add more fuel little by little the pressure still stays fine. but when you dump a large amount of fuel, by large i mean when you add fuel by percentage like 100% or more the fuel pressure drops. the more you add the lower it drops

 

Do you have access to an oscilliscope?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by servion &raquo;</TD></TR><TR><TD CLASS="quote">Do you have access to an oscilliscope?</TD></TR></TABLE>

i have no clue what that is. what is it and how do i get one?

 

Have you tried replacing your fuel damper ?
The item located on the end of the fuel rail...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mtber &raquo;</TD></TR><TR><TD CLASS="quote">Have you tried replacing your fuel damper ?
The item located on the end of the fuel rail...</TD></TR></TABLE>

thank you. i will try that tonight

 

fuel pressure? a WOT?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by servion &raquo;</TD></TR><TR><TD CLASS="quote">Do you have access to an oscilliscope?</TD></TR></TABLE>

found out what is it. going to try and get my hands on one.

im guessing i should measure how long the injector stays open and compare it to how long the engine management is telling it to stay open?

 

46 psi
at WOT on first tune is at 46

only drops pressure when adding ALOT of fuel

 

Check your voltage at the fuel pump, connections, ground. Voltage drop test while you're at it too.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDM_COUPE &raquo;</TD></TR><TR><TD CLASS="quote">

found out what is it. going to try and get my hands on one.

im guessing i should measure how long the injector stays open and compare it to how long the engine management is telling it to stay open?</TD></TR></TABLE>



If you could watch the injector duty cycle on a scope during a dyno pull, then you could see if they are at least "being told what to do correctly".... if you get down to basics, its either gotta be a delivery issue (enough fuel isn't getting to the injectors) or a injection issue (fuel is available to injectors, but they're not flowing the desired amount into the manifold).