Spark plugs

[Sapp]

Spark plugs for 2003 Malibu sunsetter xti with monsoon efi, boat had ac delco mr43lts for as long as I can remember but boat shop says they are the wrong plugs and they need to replace them with efi plugs.I have never heard of that before.Has anyone had this problem?

[formulaben]

I'm curious to hear what "EFI plugs" are.  Been using the MR43LTS plugs for 8 years, never a problem and as far as I know are still the recommended plugs.

[TXI]

Just put plugs in my 440 hour Reponse that was idleing rough around 1k, they were original plugs. After paying $10+ a piece the boat idles smooth, what a difference.

 

 

[BlindSquirrel]

Yikes… I go to rock auto and pay $1.50 each for MR43LTS. Never had an issue. I actually change them every other year… I loose more money than that in the laundry.

Edited July 25, 2021 by BlindSquirrel

[csleaver]

The Indmar spark plug chart recommends MR43LTS at 0.045 gap for the 5.7 Vortec EFI non-cat engines and 41-993 or 41-101 at 0.060 gap for the 5.7 EFI Vortex Cat engines.

[formulaben]

7 hours ago, TXI said:

Just put plugs in my 440 hour Reponse that was idleing rough around 1k, they were original plugs. After paying $10+ a piece the boat idles smooth, what a difference.

I don't go more than 3 years on a set of plugs.  For that price, I simply chalk it up to preventive maintenance.  Sure, you could go longer or just clean them each season), but either way that's way too long between plug replacement IMHO.  Lots of threads here of people chasing issues after lots of money and time invested it turned out to simply be old/bad plugs.

[granddaddy55]

i replaced mine last year after 4 almost five years that included 600 + hours, i agree if in trouble first thing snd why wait for trouble, but even with my 250+ a season currently, I think thats too frequent

i replaced them more that i might create a problem when removing them if i pushed the interval  and corrosion occurred i didn't want the hassle of getting one out thats rusted or broken with my limited skills

the indmar manual calls for every 300 hours  or annual!! as well as wires on same interval. so you are right but im guessing your  100+/- a season?  300 over three? 

i just can't reconcile that interval as my boat ran the same when dealer replaced both on  annual interval (app 100+ hours each season) in first two years as it did when  i replaced only the plugs  4 + yrs later

i get preventive maintenance but annually is nuts even with 250+ hours

BUT i am nor running snd firing corn syrup either and i have not had one, not one  ignition or fuel incident in 1115 hours over 7+’years