2005 Mag 350 MPI, idle/starting issues, have replaced the IAC+

[Texasbikers]

Hi all, have a 2005 Ebbtide with 2005 Mag 350 MPI, Engine serial # 0W320266. 325 hours on engine now, this is the first issue I've ever had with it.

Had issue with it idling after being run for 30+ mins, wouldn't idle, wouldn't start etc... I did replace the IAC at 320 hours of engine time along with the little filter in the TB, it ran great, no issues until yesterday. Back to the same issue. Normally I hit the key and it fires right up, yesterday, when it was cold I had to crank it a lot to get it to start. Once it started it ran great, we ran across the lake 30 mins, did some wake boarding, ran perfect.

Pulled up anchor after sitting for 2 hours, started fine, idled out of the cove and while sitting still, in neutral at idle for about 3 mins, the engine slowed down, stumbled and died. When trying to start it it would start, run about 400 RPM, couldn't get it to rev up or keep running, died. Over and over again tired to start it. Tried throttle at 25%, 50%, 75% WOT, nothing helped. I sat for about 15 mins with blower on and engine hood open. It finally started, ran great, I didn't let it get under 1,000 rpm until I docked it. It is weird to me that it wouldn't start, over and over trying, then all of a sudden it starts right up and runs perfect.

So, any ideas what might be going on? I did use a Sierra brand IAC replacement part #18-7701. Any chance it went bad in 5 hours of run time?

Thanks everyone.

 

[Fun Times]

Did you also clean the Throttle Body and all related component areas with TB cleaner while in there? It's normally a good idea to do so.

I see you have an Alpha drive too....Ensure that the shift cable around the engine side is not getting stuck/hung-up so where there may be a delay of some sorts while shifting, etc., 'in-turn activating the shift interrupt switch as that could slow/kill the engine like that too if being simulated somehow.

Check the fuel filter for water, debris etc..

IAC issues like what you're going through are unfortunately a bit too common and sometimes they do tend to fail in no particular order of time so yes you may have another IAC issue especially if the engine seems to be doing about the same as last time.....Also you'll want to just bear in mind that should the IAC be replaced and the engine still runs the same then there's a chance the ECM's IAC driver could be failing internally which would normally require sending the ECM out for an internal repair vs having to buy a new ECM...,https://whipplesuperchargers.com/ind...&product_id=73

Since you're in testing mode of maybe trying another part to see if things work themselves out, let's see if we can get the costs down to a bit more affordable range parts wise for you.

Being your OEM part number should be 862998, the aftermarket design for this IAC is said to fit the same an 2001ish ford windstar 3.8l V6.....Or try part number AC423.
https://www.offshoreonly.com/forums/...iac-valve.html

Hope this helps some + keep us updated and good luck.

 

[Texasbikers]

HI Fun Times, I didn't clean the Throttle Body, I will this next time and see if that helps. And I'll order another IAC, for $40 bucks that's awesome. Question, can the ECM be tested or will it show a code showing the IAC driver is bad?

I will also check my shift linkage etc.. as you suggested and report back.

Thank you.

 

[Fun Times]

Question, can the ECM be tested or will it show a code showing the IAC driver is bad?

It's a 50/50...Sometimes a code has shown up and in some cases it may not pick one up.

Using a multimeter to check ohms and voltage ranges for changes are one way to test the system...There's also a test function for the IAC found in the marine designed scan tool that may help.....To help get your mindset of how these types of systems work and test out, the following link is a pretty good video to watch if interested, https://www.youtube.com/watch?v=NzEE6OFK2Ao

But if it seems to get that far into suspecting the ECM, give whipple a call to see if they have additional testing suggestions before sending it in.