Stats:
S4 TII 3mm atkins
S5 intake manifolds
S5 turbo
720 secondaries
FMIC
2.5 exhaust
Rtek 1.7
MBC set to 12ish psi


My car is hesitating and spitting fire when ever I go over 9psi. It gets really bad. The car pulls really well if I ease into 9-10psi. Abrupt entry results in barking and garbled noises from my exhaust and jerky power.

I've gotten my secondaries cleaned and flowed.
I replaced the boost sensor
Replaced the AFM
Replaced the coils
Checked fuel pressure(38 static on aeromotive 1 to 1)
Checked TPS and readjusted


I've got a race event this weekend and I really need to be able to hit the throttle or I won't be able to use the car.

I'm going to replace the TPS completely tomorrow and remove the MBC and try boost creep and stock wastegate.

I wish I had a Rtek 2.0 right now to at least get some data logging.

Any one have these issues before?

 

oh, here's my dyno sheets from sevenstock which help show my issue

 

omg your blue torque curve went back in time!

 

replaced tps and it holds much better but it's still hesitant above 10psi.

This time I was able to fully drift 2nd gear through a turn without it breaking up and losing drift.

I may try replacing the primary injectors and efi harness(I have a built back up harness)

I'll see how the car performs tomorrow and figure out which direction to go.

I'd prefer to be in top shape while drifting Phoenix raceway but half throttle may still be ok. Turn one is 80+mph entry!!!

 

Judging from your description, and the dyno reports I am having the same EXACT problem as you are and it has been driving me INSANE!!!!! The solution I have come up with (but yet to test) is to replace the TPS (saving for a NEW one) and get the injectors cleaned and flowed, all of em. Oh yea, and check for vacuum leaks, especially around the brake booster, that helped me a little bit. Let me know how it turns out!

 

update.
Main issue was blown turbo. I killed it completely running 15 psi on thanksgiving.

Got a back up turbo on and it holds 10psi pretty good. Still hesitant on going higher but it actually runs now.

 

try checking the alternator.
of course the blown turbo wouldnt help the case.
if the car is still jerky and hesitant you might be feeding by volts from the alt.
same problem, in my car, i went through everything only to find my alt was bad.
good luck