Stft

n54boostn

New Member
Jul 21, 2019
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e92 335i xdrive
Anyone know what can cause the stft to drop to 0% during wot?

To remedy this issue. I’ve just replaced the hpfp, hpfp sensor, pre o2 sensors, crank position sensor, #6 injector and spark plug regapped to .20


580C2195-B014-41B0-88E0-D7FE6FA4A0A5.jpeg
 
Last edited:

JohnDaviz

Lieutenant
Jan 6, 2019
863
577
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335i E92 DCT
i have a similar issue with stft flatlining. In my case it seems to go along with misfire above 6k rpm.
My misfire issue is pretty weird as the CEL is not going on steadily but it was only blinking and gone when i went off throttle. After reading error codes i had misfire as active codes without CEL on.
I read somewhere that with a misfire fuel trimming goes flat.
 

iminhell1

Sergeant
Jun 17, 2018
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Not enough data.


Almost looks like it could be a PID priority issue. One coming in slower than another (STFT fast and Throttle slow). That makes it look like something is going on that isn't.
But like I said, not enough data to make any real call here.
 
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iminhell1

Sergeant
Jun 17, 2018
419
207
0
I think you have a bad injector. One on Bank 2 by the looks of it.
Something with the HPFP is going on. Pressure falls a lot but jumps back quickly. Can happen because an injector hangs open or closed, depends on what pressure is commanded (is it the high or the low?).

I think the 0 STFT is from the HPFP/injectors being uncontrolled.
It's like virtually every log of mine and others I've seen .... right around that 4,000 RPM mark shit starts falling apart.