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What the Hell is an IAC?!?! (Read 9199 times)
g
Veteran Austin Boater
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Posts: 338
Banished to an island
What the Hell is an IAC?!?!
May 27
th
, 2014 at 3:18pm
It is an Idle Air Control Valve, and apparently it is very important to a motor with the Mercruiser PCM 555 .....and if you ignore the little bastard, it will let you know in manner quite disturbing.
If you have not checked your IAC lately, read below and perhaps save yourself some headaches.
Sunny day, idling off the coast of Waikiki checking out some turtles and dolphins. I hear "2-beep" warning. I hear it again one minute later. Raise the hatch. Smoke plume from the back of my port motor. Smells like burned plastic. Shut the motor down, smoke clears. Check things out...no visible problems. Fluids full, temps good. Restart motor. 2 Beeps every minute. Idles fine. Head back to a lagoon to hang out and swim for a few hours. Restart motor, beep...beep. Still there. Pull boat out of water. Flush motors, clean boat.....beep....beep. Engines running or not, 2 beeps per minute. Put boat away for the week. Come back the next weekend and scan the motor with my Rinda. IAC, fault 152. Clear faults. IAC Fault does not clear. Stick my head back there and look at the IAC. It looks bad. Paint flaked off and the connector is melted...fused to the pigtail harness. Crumbles in my hand. Holy SHIT! I was incredulous. The plastic was melted as if it were on fire. I needed a new IAC and a new harness. Fortunately, Merc makes a replacement pigtail with instructions and merc approved heat-shrink butt connectors in the package. Several weeks later new parts arrived and I set about replacing the IAC and the burned out connector. Fault beeps immediately gone and IAC duty cycle tracks as normal on the Rinda. I actually feel lucky that I caught it before I ran the motor too much longer. There have been cases where a burned IAC fried the PCM. Below are some pictures for your viewing pleasure.
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Fault152.JPG
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Connector1.JPG
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Connector2.JPG
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IAC1.JPG
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IAC2.JPG
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newiac.JPG
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pigtail.PNG
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2006 32 Sunsation SS MCOB
2007 2500HD Allison/Duramax
2007 Corvette C6
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My Z06
Land Lubber
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Austin Boater
Posts: 19
Re: What the Hell is an IAC?!?!
Reply #1 -
May 27
th
, 2014 at 4:16pm
You were in open water and decided to keep driving despite seeing smoke and smelling something burning? You are Much braver than I!
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g
Veteran Austin Boater
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Posts: 338
Banished to an island
Re: What the Hell is an IAC?!?!
Reply #2 -
May 27
th
, 2014 at 6:28pm
My Z06 wrote
on May 27
th
, 2014 at 4:16pm:
You were in open water and decided to keep driving despite seeing smoke and smelling something burning? You are Much braver than I!
Not bravery. Judgment. Boating in the ocean presents a different set of environmental factors that a reservoir simply does not have. You make decisions based not only on the mechanicals of the boat, but the sea state, water depth, proximity to the reef and weather. Float there and fret about what might be going on with one motor and you may just find your vessel on the reef, inside the surf. The beauty of twins is that extra motor to get you and your crew home safely and your investment back on her trailer to fight another day.
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2006 32 Sunsation SS MCOB
2007 2500HD Allison/Duramax
2007 Corvette C6
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BADFISH
Austin Boater
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Austin Boater
Posts: 51
Sugar Land, TX
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Re: What the Hell is an IAC?!?!
Reply #3 -
May 27
th
, 2014 at 8:41pm
IAC took out my ECM a couple of weeks ago. You were lucky! I replaced both and now carry a spare.
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JC
Veteran Austin Boater
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Austin Boater
Posts: 254
Cedar Park
Re: What the Hell is an IAC?!?!
Reply #4 -
May 27
th
, 2014 at 8:42pm
What's the deal with boats and IACs? I hear of them failing so frequently people are carrying spares with them.
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29 Fever w/twin BBC
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JC
Veteran Austin Boater
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Austin Boater
Posts: 254
Cedar Park
Re: What the Hell is an IAC?!?!
Reply #5 -
May 27
th
, 2014 at 8:43pm
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29 Fever w/twin BBC
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nathan
Lake Admiral
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Going Home !!!!!
Posts: 2120
Leander, TX Soon
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Re: What the Hell is an IAC?!?!
Reply #6 -
May 27
th
, 2014 at 8:55pm
wow G that sucks!! Glad you and your crew was able to get back safely!!
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My Happy place is on a boat at the lake with my kids!!
current boats:
1983 chaparral 235 XLC (restoration)
1977 playcraft p24 pontoon (parents own now I am the mechanic)
1975 skeeter hawk (on hold)
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g
Veteran Austin Boater
Offline
Posts: 338
Banished to an island
Re: What the Hell is an IAC?!?!
Reply #7 -
May 28
th
, 2014 at 2:45pm
BADFISH wrote
on May 27
th
, 2014 at 8:41pm:
IAC took out my ECM a couple of weeks ago. You were lucky! I replaced both and now carry a spare.
damn! Sorry to hear that about your ECM. I replaced both IAC's and took the "good" one on stashed it as my spare.
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2006 32 Sunsation SS MCOB
2007 2500HD Allison/Duramax
2007 Corvette C6
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97FASTech
Veteran Austin Boater
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Canyon Lake Boater
Posts: 278
Canyon Lake / Houston
Re: What the Hell is an IAC?!?!
Reply #8 -
Jun 5
th
, 2014 at 11:51am
I'll see your IAC's and raise you a top end rebuild!!!! LOL
Fingers crossed.
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g
Veteran Austin Boater
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Posts: 338
Banished to an island
Re: What the Hell is an IAC?!?!
Reply #9 -
Jun 5
th
, 2014 at 4:53pm
Touche
'
Sir.
Here's to a speedy repair. See you in Kemah a few weeks!
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2006 32 Sunsation SS MCOB
2007 2500HD Allison/Duramax
2007 Corvette C6
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Captain YARRR
Admin
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Doing the rain dance
Posts: 2587
Round Rock, TX
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Re: What the Hell is an IAC?!?!
Reply #10 -
Jun 6
th
, 2014 at 10:06am
Let's definitely not make this a competition, we all lose
Bob has got me for a coil wiring harness connector this week, we'll see what else. Glad I've been running the heck out of my boat to find these little bugs before we're running hard out there.
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2005 Sunsation Dominator 32 MCOB - twin 6.3L
2004 Dodge Viper SRT-10: 460 RWHP, 503 RWTQ
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