SoSlo

ok
the setup:
b18c1 block
low comp
turbo
tuned on crome
been running great for a long time


she runs great when the motor is cold.
when she warms up i get a studder under load. when it studders it will start to backfire and keep doing it if i hold the load. my ECU shows i am squirting fuel, while my wideband shows lean( i get a black cloud)

this studdering is not dependant on RPM, SPEED, High/Low Cam, Just load.

Like i said it runs great while cold
I am not getting any CEL's

HELP!!!!!!!!!!!!!!!!
This one is got me.....

quicksi69

I had kind of the same issue...
The 1st tuner who tuned my car couldnt figure it out...
2nd tuner fixed it by me doing a few pulls on the street and him tuning it on the street.
My car would always sputter arround 4,000+ rpm

SoSlo

it has nothing to do with RPM, it will studder at 1000 rpms when starting off or at 7000 while just messing arround. it is all load dependant

HiProfile

The wideband doesn't detect fuel, it detects oxygen. When you get a misfire, the raw gas and unused oxygen are detected as a lean condition by the wideband. When you backfire, it's because unburnt fuel/oxygen is getting ignited in the exhaust when the next piston exhausts a burning mixture, or it hits a turbine that's hot enough.

Usually this boils down to your ignition not having enough power - for several reasons. If your plugs are fouled or old, the coil simply can't overcome the gap or resistance. Copper plugs don't last 50k miles like iridiums. You could also have a failing coil, which doesn't have enough to ionize & jump through more-dense mixtures. You could also be having valve sealing issues, but that usually has other symtoms.

SoSlo

this only happens once the motor warms up. the plugs are less than 5 k miles gapped at .028. this setup ran great for several years... thanks for the input. i will check my coil later when it warms up outside

SoSlo

no more help? i ordered a coil but it wont be here for a few days.

NonovUrbizniz

02 sensor? Does it do break free of the bog if you go WOT?

Could also be the IACV or FICV but those would have to be pretty F'd to cause that much of a problem.

Definately sounds like a major fueling issue probobly sensor or program based if it's only happening once warmed up...

turbociv910

do the s2k map whack

SoSlo

no it will not break free under WOT...

I have tried burning new chips and changing the maps with no luck.

my ECT is steady at 180*
my IAT is arround 100*

my ecu shows that the injectors are squirting but the wideband shows lean. meaning that it is not getting burnt. that mixed with the backfireing leads meto believ that it is a timing issue/ ignition.

Bailhatch

It does sound like an ignition problem.

Turbo-LS

iTrader: (4)

for the heck of it gap the plugs down to .025 see what it does.