Possible IAC Issue

mvnmvn Member, Moderator Posts: 744 mod
edited July 2017 in Engine Discussions
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
Good,  fast,  cheap.... pick two. 
2019 MTX20 Extreme

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