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.

Bup, what is normal operating range for 502Mag/EFI? How high is considered problem? Mine varies a lot with ambient and lake temp.