Possible IAC Issue

mvn

So here's my story....... 

2008 5.0L Merc MPI on an Alpha.  Over the last few years it would occasionally stall out when pulling the throttle back to neutral after towing a skier or tube. It would start up right away.  No WOT issues whatsoever. 

Frequency of stalling has been increasing accompanied by longer and longer cranking times.

Assuming a bad IAC, I replaced it today.  Instantly observed better starts (just touching the key).  Problem is that the stalling is even worse now.  Shifting into neutral from forward and neutral to reverse causes a stall almost every time. 

Now, with the engine running, I pulled out the IAC filter and the engine immediately stalled.  The filter was totally disintegrated and just crumbled in my hand.  I made up a quickie with some breather foam I had on hand and now no stalling. 

Am I correct in assuming that the PCM was seeing a lean condition when going to idle and cutting fuel?  Could the IAC filter be that critical? 

Mark

mvn

Will do, thanks Al!

Mark 

skennelly

Where does the filter go?  I just installed a new IAC and didn't notice a filter.  I also got mine at the auto parts store...2002 Ford Windstar IAC.  Boat ran good after I changed it.

Dream_Inn

If the flyer doesn't fix the problem, it could the shift switch.  With the alpha drives, you have momentarily switch that will stall the engine if not set up correctly.  Easy adjustment.

mvn

Dream_Inn,

I thought about that but what I am seeing is a stall occurring very slowly after about 5 seconds in neutral after pulling back from mid-throttle.  Just waiting on a replacement filter.  None in stock locally.  The one I made up seems to be doing the trick though.....

Mark

mvn

Resurrecting an old thread.....

Tried replacing the IAC with an aftermarket clone....ran worse.  New filter didn't really help either.  Bought an OEM Merc IAC.  Problem solved.  Quick shifts do not cause the engine to stall.  No hunting or undershooting at idle.  All good now!

Mark 

Dream_Inn

Good to know.  I'm with someone right  now that is replacing his today.

Spyderweb

Is the filter below the butterfly valve in the throttle body?

mvn

No, it is between the IAC and the throttle body.

Mark

Spyderweb

Is this the correct filter for a 350 MAG 5.7?
https://www.wholesalemarine.com/muffler-iac-mercury-mercruiser-35-863829.html

mvn

No idea.

Here is the official parts lookup app....

https://public-mercurymarine.sysonline.com/Default.aspx?sysname=NorthAmerica&company=Guest&NA_KEY=NA_KEY_VALUE&langIF=eng&langDB=eng

Mark

Cableguy Greg

Spyderweb said:

Is this the correct filter for a 350 MAG 5.7?
https://www.wholesalemarine.com/muffler-iac-mercury-mercruiser-35-863829.html

Yes