I have a 99 civic si with a vortech supercharger. I recently got some 440 injectors and did the vafc hack.
My settings are
1000 and 1500 -40
2000 and 2500 -39
3000 and 3500 -38
4000 and 4500 -37
and so on....
my problem is when i try to hold the rpm's at between 2000 and 3500 rpm....every second they drop down about 500 rpm's then they go back up. When i richened the range from 2000 to 3000 up to -30 and from 3000 to 4000 up to -29....my problems go away but it is very rich. does anyone have a cure for this problem?

 

are these used or new injectors? could it be a flow problem? check your wiring on the injectors and afc to make sure everything was done good

 

i have the same problem.

 

the hack seems to run very differently fromc ar to car even with the exact same setup. its weird but you just have to either play around with it until you get it running good or bring it down to get it tuned.

 

they run fine under load its only when you dry to hold it during idle like when you are going to launch.

 

they all do that. It's not really a problem. Cars with the blue box do it too.

Good luck.

 

was this on a dyno???

where did you get these #'s

btw i saw your same post on clubsi.com

 

they were new injectors.
so this is normal, and i shouldnt be worried?
would an adjustable fuel pressure regulator solve anything?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 808b18c1boosted &raquo;</TD></TR><TR><TD CLASS="quote">they run fine under load its only when you dry to hold it during idle like when you are going to launch.</TD></TR></TABLE>

exactly.....except mine does it in 1st gear if i try to drive along at like 3000 rpm....it surges and bucks around.
does yours go away if you richen it up?

 

sounds like you need to lean it out rather than richen it up....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Johnyquest &raquo;</TD></TR><TR><TD CLASS="quote">they all do that. It's not really a problem. Cars with the blue box do it too.

Good luck.</TD></TR></TABLE>

not all, i dont get part throttle hesitation and neither does my friend, but my cousin does and we couldnt get it to stop no matter what we did. i never had it when i was running the bluebox either, but yea but alot of people have this problem. i believe its because the ecu cuts fuel at a certain point (when not wot) and the vafc is also cutting the fuel by around -40% (depending on your setting) which causes this bucking or hesitation

 

You're running against injector cut; ECU thinks engine vacuum is greater than it actually is since you are dropping MAP imput voltage by ~40%. As the fuel cuts on/off you get an rpm fluctuation... it manifests a little different between OBD0 and OBD1 and OBD2.

Well, you riceboys paid $300 for an AFC with a ghetto interface versus $50-100 for a chip burner with an easy to use intuitive interface and freeware boost tuner application that is also an intuitive interface. Quit your bitching and live with your hack.



FYI, since parting with my OBD1 conversion I run a variant of the hack (again)... does a wonderful job of tuning AFR under cruise/load/boost once you address ignition timing issues. Stop expecting it to be perfect, it's a piggy back system that ***** with the stock ECU, it will NEVER be perfect.

 

What would happen if i put the missing link back on, would that take care of the problem?

 

the closer i get to -30 at 2000 and 3000 rpm, the farther apart the surges get if that makes sence