Raise the idle on a 5.7 mpi
 

Does anyone know if you can raise the idle with a rinda tech mate pro scan tool?

On stock MPI Merc and all other OEM stock MPI engine apps Idle speed is non adjustable. If you are having problems with low idle speed there is a reason for it and or a problem that needs to be addressed .

I've been having trouble with reversion. having slightly higher rpms seems to help keep things dry.

Could probably do it with MEFI burn.

Not if he has ECM 555

So with that said what exactly do you have and your set up along with the ECM

Do you have alpha or Bravo outdrive ?

Too high of idle is an alpha outdrive killer another reason why Mercruiser recommends and keeps idle speeds at the 600 to 700 rpm's.

Was your cam changed in this app

have you pressure tested the exhaust manifolds and riser together ?

What exhaust system do you have here ? Merc OEM dry joint manifold & riser ?

Is your exhaust thru the prop or silent choice or straight out transom ?

A lot more info needed -

Possible need riser extension blocks as your waterline to relation to the boat / exhaust is too high

Have no idea what you have here so throwing out some ideas

If a stock 5.7 is reverting water, you have an issue somewhere else.

Go to your tool box and find your cordless drill, next find the biggest drill bit you have. Drill one hole on the top side of the intake manifold, that should let just enough air in to raise your idle.:party-smiley-004:





Like many have said your idle is set(adjusted) by the ecm thru the IAC motor.

Exhaust manifold or intake gaskets is my 1 and 2 guess

The motor is a bone stock 5.7 mpi 330hp with a new stainless marine exhaust system that is 6in taller and has longer risers made to help stop the reversion. I've been having this problem since day one. I had a thread going on this topic while ago with little success. I had the heads repaired cause of valve seat damage. After a day of running I check the exhaust the port side will be dry but the starboard wet. After I flush the motor both are wet but if I keep the rpms up they're dry.

OEM stock Mercruiser 5.7 MPI does not have a 330 hp. 5.7 - HO mag is 300 hp