E85 tuned to 17psi, bmw VTPS, MS, 850cc injectors DW fuel pump. Ran good. Now it sputters only when it gets to half throttle or more. Idles and cruises good at quarter throttle, can even get to 90mph 3-5psi just fine. But once I get to half throttle it just sputters and goes no where. AFR’s stay the same when this happens around 13. Not over boosting either. any ideas?

 

What’s your fuel pressure when this happens?

 

I’m not sure, I will buy a gauge and find out