Ok we have a LS turbo that is ~9lbs of boost
440 rc injectors
safc
-50% 1-5
-42 5-7k
-25 8k

the car sputters at 1-3k and then hits a wall around 5.5k rpms

we threw a code 41 and 43 which is O2 sensor and fuel supply, i think its running too rich up top

what would cause this?

 

are you running the AFC Hack???

Post the setup

jon

 

i know i had code 43 and i changed the o2 sensor and it went away..

 

no i dont think this is the hack.

there is a low pressure fmu inline
with the safc
and the 440 injectors

 

so your running a fmu and the afc hack?? that's alot of fuel... what do your plugs look like?

 

i dont know why, this is my friends setup.

I use uberdata.

the fmu should not effect the stuttering at low rpms.

The only way I can explain it, is you rev it in neutral, and it hits a rev limit at 2k 2.5k and 3.5 k

if the gas is held steady it will rev, then drop, but if you give it more gas it will rev on by.

basically it bucks at low throttle input and then runs good from 3k to 5 or 6k then starts popping and backfiring.

the plugs are gapped to .30

 

change the o2 thats what it is, thats what the fuel supply code is from

 

if ur running the hack ditch the FMU, to much fuel...my friend hit a wall around 5k also, 550's and an FMU, ditched the FMU and set -40 across the board, even with -40 across the board and the initial running of the car before adjusting the fuel it ran ten times better. ditch the FMU and work it from there

 

we fixed the problem, it was the mass air flow sensor check valve, it was bad and wasnt letting air get to the mas at all

 

I think I have the same problem it started happening after i put the test pipe on and put the o2 cen into the test pipe. How can i fix this problem? Ditch the test pipe and get a high flow cat and place the o2 cen back in the cat?