496 ho help (again)
 

help again

--------------------------------------------------------------------------------

I understand that this has been visited a "million" times, so one more won't push you all over the edge I hope!
2007 496 ho IAC issue question is if I replace it do I still have to hook up to computer to clear code or will it "auto fix"? my tech says bring it in again, wow thats 2 days out of my life & he just replaced them! (port still alarming) Any advice?
Thanks Jimmy

if the iac was just replaced.... check the harness connector that plugs into iac. they will actually melt and cause it to set that code because of conn. shorting out...replace the pigtail. just my $.02..

My IAC burned up at the end of summer, I repalced it along with the melted connector. Alarm did not go away. I took my boat to the local Merc dealer and he said my new IAC was not getting a signal. I tracked down the wiring and all was good. The computer sends a ground signal to the IAC. The melted unit cooked my computer. Whipple is repairing it. Dustin said it is very common for the bad IAC to burn up the driver in the computer.

Sounds great i have 2 off them waiting to spoil my day .
Are there any early warning signs that the IACs are going bad.

Or should it be changed as a regular maintaince item?

Good question, I didn't know I had a problem until my alarm sounded, then it was too late. I got ahold of some bad gas that possibly could have helped cause the isse. My 496Ho is whippled and needs 91octane.

My next engine will be a carb and a Mallory distributor. Can draw the entire ignition system on a piece of paper out of my head in 1 minute. I like simplicity.

Thanks for input guys, took boat to ugly johns to repair starboard iac (harness melted), so had them replace all 3! Port engine had no previous alarm. Travis at ugly johns says new iac may be bad. Idk just want to go bajaing w no alarm! On my way back again I'm sure.

Can that Mallory dist and carb back off the timing 30 degrees if it senses knock? How about running optimal on a 100 degree day, and safe on a 60 degree day?

Yes, carbs are simple and easy to repair yourself, however computers watch over things and in mist cases keep you from blowing up.

Anyone with an efi engine should have this
http://www.mefiburn.com/sc/details.asp?item=mefiscan1

For 200 bucks you can see everything you need to, for 600 bucks you can make adjustments to the mapping!

Why guess or wait for a marina to scan?

EFI is cool but pretty much unnecessary. It is overkill on your average boat (like mine). It will never knock and will run fine at 100 degrees or 35 degrees with a carb and mallory. I will never know the difference until there is a problem, then EFI is a nightmare x10.