SR missing backfire under boost

[theianmcdougall]

car
1991 s13

motor
redtop, s15 t28, z32 maf, 550's, enthalpy ROM tune, walbro 225



So up until recently the car has been running fine. Now lately when i get into boost, everyonce in a while, ill hear it backfire really loud and a loss of power for a second and then i can usually get it all the way up the RPMs but it doesnt feel safe or like its funning right

-Could it be timing? moved the cas sensor back and forth a while back but it ran pretty well
-bad plugs? have ngk's i put it about a year ago, but i doubt the car has seen more than 1500-2000 miles
-fuel? i have aem wideband and apexi safc, and the afr's look safe throughout boost


please help
thanks guys

[benarovi561]

check the gap on the plugs if its breaking up into boost

[theianmcdougall]

yea thats the next thing ima check, might play with timing a little too

[RACETUNE]

What plugs do you have in the car now?





***If you have an issue with your vehicle and every Shop and/or Specialist you have tried failed, and you just want someone that will do it once and right the first time. Or you need a Dyno Tuner with many years of Racecar tuning experience. Hit me up.

[steve shadows]

car
1991 s13

motor
redtop, s15 t28, z32 maf, 550's, enthalpy ROM tune, walbro 225



So up until recently the car has been running fine. Now lately when i get into boost, everyonce in a while, ill hear it backfire really loud and a loss of power for a second and then i can usually get it all the way up the RPMs but it doesnt feel safe or like its funning right

-Could it be timing? moved the cas sensor back and forth a while back but it ran pretty well
-bad plugs? have ngk's i put it about a year ago, but i doubt the car has seen more than 1500-2000 miles
-fuel? i have aem wideband and apexi safc, and the afr's look safe throughout boost


please help
thanks guys

Is it a "backfire" or is it a rev limiter feeling a little bit quieter missing? It sounds like it could be the ground for the coil packs or dist/coils

[theianmcdougall]

^ i just put on the autometer tach adapter for a different tach, and to wire it up i had to bridge the white coilpack wire that seperates and goes to all 4 coils with the tach adapter, wonder if that messed with anything?

oh and its backfire like its suddenly missing and but still not sure since afr's look fine

plus im running open downpipe at the moment but thats not the problem just makes the backfire/missing alot louder, hah

[theianmcdougall]

help me fix my sad purple car...
http://i54.tinypic.com/zvvf38.jpg

so i can get back to this :)
http://i51.tinypic.com/2rxw9ll.jpg

[Phatsilvia]

probably bad plugs their a year old, they can go bad from sitting, what number plug are you using and make sure their gaped properly, unless you have a bad CAS