hamburgler

ok this is kinda of a long story, but ill make it as short as possible. i had an old lsvtec with about a 10.5:1 compression ratio with the gsr pistons and stock head and ls block. i had it tuned to perfection with dsm 450's and crome. it ran a 13.3@110mph on street tires. the tune was about 22* timing from 5500-8000 and about 11.5-11.8 afr all the way in boost.

anyways i wanted something faster so i just built an ls vtec with 81.5mm arias pistons and eagle rods and the whole head since it was off. i now have an 8.57:1 compression ratio.

so im done my break in now so today i started to tune...hit boost and go over 4500rpm. however i started off with my old map from the 10.5:1 build mentioned above and now in boost (4psi) at 5000rpm i cant get it to richen up at all. i keep adding fuel and adding fuel...im over 90% duty cycle now at 5000rpm and its stilll a 14.9:1 fuel mixture. will a compression ratio make this much of a difference? i thought for sure i would be able to use 450's for 7psi boost. can anyone give me some guidance as to whats going on?

ps, im still getting some blowby out the valve cover breather at idle, i didnt get any with my old motor so the only thing i can think of right now is that the machine shop might have messed up the bore so some of the oil is mixiing with the gas upon compbustion and creating a lower octane level for the fuel. could this happen?

0b00st0

Does the wideband even work?

hamburgler

well i guess thats another thing to look into but i pulled the plugs to check and they were indeed running hot. there was a nice white tone to the tip and no light brown what so ever on the plug.

at the moment i think my fuel pump is pooched so im going to richen up my idle to see if in fact my wideband is working and the fuel im adding is actully getting added.

zebvaj

Depending where your vtec cross over is. Are you adding fuel to the right map as in your secondary map?

hamburgler

yes,im aware of a high and low cam

zebvaj

Just making sure you aren't adding fuel to the primary map like some other guys and wonder why afr doesn't change after they hit vtec.

quadtech

what chassis is the motor in.

I had a similar issue with a LSvtec on crome. motor was in a 91 teg obd1 converted with 450 dsm and a resistor pack.

i couldnt get the car to richen up at all in boost and the a/f's were totally wonky.

ended up being that with the low impedence injectors and the resistor box the maps werent being affected.

ditched the resistor box, put in 450 high's and everything started working like it was supposed to.

hamburgler

ya, but i have had everything working fine like a month ago and for the last 2 years. i find it hard to believe that since i rebuilt my motor the injectors and resistor box went wacky. im just going to keep adding fuel to my idle since it doesnt require much pressure and see if i can get it to richen up there. if i can richen up my idle then it must be my pump. but the motor has never bogged

bitchasscracker

is it just the stock pump