need help with studdering problem

[sb7775]

mod list
fresh motor 170psi all cyl.
small 16g
full 3in exhaust no cat
k-n filter
1g mas hacked and screw backed out
255pump
stock 1g manifold and o2 ported by me
afc
boost and egt gauges
2.5 uicp
my problem is that around 4500-5000rpm my car stutters some. then it clears up past that. i have tried to lower boost down to 11psi but i get the same problem as i have at 16psi. i have tried a new coil and igniter, fresh plugs( bpr6es .032 gap) and wires(ngk)
different fpr and injectors. i have checked for boost leaks,changed my computer and bov.the car car likes to run lean by normal standards. if i set the car to run around .88-.91v its like it hits fuel cut there(16psi). if i set the car to run .80-.84 it pulls well(besides my sputter) and the egt,s never go over 1450(16psi). when i set the car at 11psi the egts never went over 1300. but i still had the sputter. her is a log from 11psi. thanx for the space any help would be greatly appreciated. thanx steve
11psi
rpm tps injp knck tima o2-r mafs
4156 98.8 16.63 7 19 .93 1182.5
4343 98.0 17.15 5 19 .91 1289.4
4500 99.2 17.15 4 18 .91 1327.1
4750 98.0 18.43 3 18 .91 1471.8
4906 99.2 18.43 1 20 .89 1541
5187 98.0 18.94 0 20 .87 1585
5218 99.2 18.17 0 22 .87 1515.8
5281 98.8 17.91 0 21 .87 1603.9
my isc sits around 39.4,cool 102.5,airt 35., baro .99, batt 13.6-14.0,egrt -21to-27
i have also tried a 2g mas with the same results. i'm thinking 550 and a afpr and maybe a different mas set up. for some odd reason my tps looses 1-2 % and my mas actuall went backwards also but none of this happens when the car is sputtering. my next try i think is injectors unless i can get some outher idea. if anybody local would like to help out give me a call thanx steve 508-415-8281 fallriver MA

 

[sb7775]

forgot to add the car has a new knock sensor. thanx steve

 

[terminaltsi]

i am currently dealing with the same possible type of problem. i have noticed that when the stuttering starts, my egt's drop way down... i'm tinking that i'm really rich even though i was at -20% on hi on the afc at only 1.2 bar boost. so i've been turning the fuel down until i'm currently at -35 on average above 4k rpm. it seems to stutter much less and egt's are getting better. still not good hoever. i'm almost afraid to pull much more fuel out.
i have 650 injectors, 255 pump, afpr, and the other usual mods.

 

[4G63 GST]

terminaltsi .. is your mas hacked ? just curious?

 

[sb7775]

yes it is. i tried 3 different ones thanx steve

 

[4G63 GST]

shit this is scaring me .. i was planning on taking out the honey comb to relieve my fuel cut problems..


I have a 90 1ga


Luke