Re: 4 stroke yammi/rough idle
next time its acting up put your finger on the ISC valve, if its to hot to touch it may be failing. the valve sometimes gets to hot and mechanically binds and cannot move, then it gets really hot. if it cant move or is sticky it cannot control idle air and the result is rough running and stalling, most common when deaccelerating.
to my knowledge there are no tech bullitens about excessive fuel rail pressure, there is a tech bulliten on excessively rich starts due to the fuel percolation when the engine is shut off hot.
with a temp gun the ISC normally runs around 130*F, abnormal ones run over 200*F.
EFI is incredibly easy to trouble shoot if you can make the problem repeat.
on the laptop the symptoms will show up as a higher than normal manifold pressure for the amount of throttle opening, in fact occasionally a tech will replace the map sensor due to a code when in fact it was the ISC.
if the fuel rail is overpressurizing it will create a very rich fuel mix but is easy to detect with a fuel pressure gauge and is normally due to a bad pressure regulator.
