Thermostats
 

Has anybody run their 502 EFI Mags with the thermostat removed? If so what effect did it have?

For what reason would you want to ?

I removed them for winterizing and I was just wondering.

Its important that an engine gets up to the proper temp to run its best , this EFI engine is designed to run a stat, Id put new ones back in

Like it was stated by f2 I would highly recommend putting them back to make sure motor runs at the optimal performance. Running no t stats could be a bigger issue due to temps.

Reduced water pressure in intake may cause steam pockets in heads. More heat . Boom

the coolant temp is one of the inputs to the ecm for the ecm outputs to command fuel injector pulse widths. The fuel table mapping will be rich. for a jist of info.

fyi,,,my old set up had no thermostats,, but after i changed some things added 160's.
as said , u want the temp 160 plus....

and for more info most other engine brands of efi / mpi engines guardian the rpms when the engine does not see min of 140 to 142 coolant temp. With that said for people that have went from a 160 T stat to a 140 T stat that would not work out so great for those owners.

Also no matter of engine brand a fully stuck open T stat will make the engine run rich. Even 4 stroke outboards and they will make oil.

502mpi's should run consistently at 160-175 on the gauge once they have reached operating temp

raw water cooled or close cooling ?

scan tool reading 155 to 172 can be the normal range for raw water cooled.

Water circ pumps also can cause swings in coolant temps, Basically meaning if its 12 years old or older its time to change it. Also air bubbles in the cooling water flow causes temp swings and off readings