Is fuel cut dangerous?
- Thread starter jake8790
- Start date
jake8790;1909798 said:
Seems you're running a 57 trim turbo with no lex afm. I did the same thing and when I opened up the turbo elbow, it did 11 psi without a boost controller which was hitting fuel cut.
Fuel cut isn't harmful persay, it's a built in safety measure. Fuel cut is keeping you from harming your car. Easiest way around it is 550cc injectors and the lex afm.
If you are worried about the engine running lean because the fuel is being cut off... It won't happen.
FCO is a built in safety, and Toyota wouldn't design it to cause bigger problems.
FCO is a built in safety, and Toyota wouldn't design it to cause bigger problems.
jetjock;1909955 said:
Probabaly just because it is pretty violent when it happens. I know when I first hit fuel cut when I bought my first turbo I was like WTF!! Did I blow the motor already?
It's just a shock when you are pulling hard then lose all power and jerk forward.
I wondered at first about it "running lean" with a partial fuel delivery, but I'm satisfied that doesn't happen. FCO also happens when you let the throttle snap back to closed with engine RPM over about 2,000 RPM or so, too. That happens often enough to assure me that it's both safe from an air/fuel mix point of view as well as from a mechanical stress point of view. If anything, the stress on the motor is greater when you snap the throttle closed, since with the throttle plate closed, engine braking is greater. (Assuming that your clutch is engaged, of course.)
Dan_Gyoba;1910115 said:
What?
Especially this part "FCO also happens when you let the throttle snap back to closed with engine RPM over about 2,000 RPM or so, too."
It's in the TSRM. When IDL is shorted to E2 at the TPS and RPM is greater than ~2000 (I don't recall the exact RPM), the ECU activates FCO.
It's the "running lean when FCO happens" part that doesn't make sense since detonation can't occur under those conditions.
Dan_Gyoba;1910115 said:
Not that it really matters, but there is a delay after the throttle closes before overrun FC is activated.
jake8790;1909798 said:
No. Running lean is harmfull. Shutting the fuel off and using the engine like a compression brake does not hurt it. Partially fueling at that point is harmfull.