Strange missfire only at light throttle and when hot
Strange missfire only at light throttle and when hot Problem has been going on for about 6 months now and is worse on e85 than gasoline. The issue is getting progressively worse now. It drives fine when cool, but once the coolant temp gets above 180ish it starts to miss gradually then gets really bad. It runs fine under a moderate load and under boost though. A/F leans out when the missfire is happening too so I'm thinking it's a fuel problem.
Fuel is controlled by a megasquirt 2, timing by stock ecu. stock returnless setup, dual in tank walbros.
steps taken so far:
Changed plugs
changed fuel filter
Fuel pressure appears to be holding at idle, but drops 5-10psi on a hard rev. If the drain is pressed on the pressure gage while the car is running the fuel pressure drops from 72psi to 42psi and stays there as long as it's held. When the car is cold the fuel coming out of the drain line is a smooth flow, after the engine is heat soaked the fuel coming out is aerated and foamy which seems strange.
Things left as suspects
plug wires
fuel pressure regulator in tank
looking for ideas.
Fuel is controlled by a megasquirt 2, timing by stock ecu. stock returnless setup, dual in tank walbros.
steps taken so far:
Changed plugs
changed fuel filter
Fuel pressure appears to be holding at idle, but drops 5-10psi on a hard rev. If the drain is pressed on the pressure gage while the car is running the fuel pressure drops from 72psi to 42psi and stays there as long as it's held. When the car is cold the fuel coming out of the drain line is a smooth flow, after the engine is heat soaked the fuel coming out is aerated and foamy which seems strange.
Things left as suspects
plug wires
fuel pressure regulator in tank
looking for ideas.
