I have a b20vtec with:
crowler stage 2 cams
je high compression pistons
eagle h-beam rods
some other minor stuff and tuned with honda s100(i think, may be s200)

It has been running perfectly fine for the last 14000 miles and today i was driving and the engine cuts out and backfires really bad when i hit the gas any harder than 1/4 throttle. I checked the vacuum lines and one of the caps was split in half so i changed it out and thought it was fixed but the next day it started doing it again...any suggestions or questions that will get this car running again??

P.S. I'm looking to sell it once i get it fixed if anyone is interested, its in a 99 civic si with custom paint(not tachy) ran a 13.6 in the quarter.

 

hrmm... is it tuned on s200 or s100? you can straight out tell if its a s200 unit if you see a little blue box hanging out side the ecu.. anyways what kind of fuel pressure regulator do you have? adjustable with fuel gauge? what fuel pump are you using? those might be the problem.. if not then try and change the ecu

 

Its s100, sorry.... im using a walbro 255 fuel pump, i dont remember the FPR make, but i have adequate fuel pressure both when the car is off and when the car is running

 

well if you have an adjustable FPR then I would check the psi on the gauges.. make sure it isnt running like 60psi or something because a wahlbro 255 pump on a stock FPR usually tend to bump up the psi to like 60psi which will make your car run really rich.. I would say stay 40psi..

 

But why would it all of a sudden start messing with the mixture after 15000 miles, my first thought was a vacuum hose or something along that line

 

I donno.. well check your psi and get back to us.. Tell us where its at

How about your injectors? what are you using? cc? low impedance, high impedance? resistor box?