496 mag ho issue (solved)

[Rsqfxr]

Well, here is my experience with my 496ho, my last trip out was the weekend after labor day halfway through the weekend I started getting 2 warning beeps every few seconds and anything over about 50% throttle resulted in a solid tone until the rpms came back down, all gauges looked to be ok, drive reservoir was a little low so I added fluid, still having the issue and the one trip where I forgot my scanner, ended up turning up the stereo and finishing my weekend, when i got back I scanned it and pulled various codes 132 crank sensor, 77 cam sensor, 3 sea pump psi low, 152 iac output,. Hanging around the offshore forums for a bit led me to check out the IAC Valve and what do you know the shit was melted just as they described, they provided gm and ford part numbers, I think it was like $40 and Im back in the game.

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[CobraDave]

Awesome I love when things go that way. Cam sensor and low psi Sea pump would have me thinking the worst.


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[Rsqfxr]

Awesome I live when things go that way. Cam sensor and low psi Sea pump would have me thinking the worst.


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I was thinking no way on the low psi I put in a hardin marine setup a few trips ago


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[Heylam]

I had an iac go bad in one of my boats with a 496HO, and it was difficult to diagnose. Didn’t melt, so not obvious. When I replaced it (Ford part), I bought an extra to keep in my spare parts bin.


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[nowski]

Rsqfxr, besides the audible beeping alarms were there any other warning signs like an idle whistling noise?

I guess it's good to carry a spare since it seems to be a common problem...

 

[Rsqfxr]

Rsqfxr, besides the audible beeping alarms were there any other warning signs like an idle whistling noise?

I guess it's good to carry a spare since it seems to be a common problem...

No, nothing other than the beeping, thats why I continued my weekend


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[Shlbyntro]

It seams to be a common issue across the board on all pre fly-by-wire mpi motors. I replace at least a dozen a year. Be sure to check available engine power next time you're plugged into a scanner. Those water psi sensors go bad too (Imo they're a nuisance sensor) but despite no running issues they will limit engine power to 90-95% that the ecm will report to you when they do. Mercs usually don't use a cam position sensor and that one is normally a phantom code. Not so much for the Volvo I just worked on that ate my lunch. Lol

 

[Wizard29]

they provided gm and ford part numbers, I think it was like $40 and Im back in the game

What year is your engine and what were the GM/Ford part numbers? I might like to buy a couple of these to keep handy for my engines.

 

[charlyox]

Thanks for sharing this information. [emoji106]


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[Rsqfxr]

What year is your engine and what were the GM/Ford part numbers? I might like to buy a couple of these to keep handy for my engines.

Mine is a 2004 this is the delco one I ordered

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[rrrr]

.

Forty bucks to fix a boat? That's unpossible!

.

 

[Runs2rch]

Mine is a 2004 this is the delco one I ordered
View attachment 714438


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How many hours are on yours?

 

[Ultra912]

Was it the typical beep like Drive oil beep or was it different than the drive oil I’ll beep

 

[Rsqfxr]

How many hours are on yours?

Around 250 hours


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[Shlbyntro]

Was it the typical beep like Drive oil beep or was it different than the drive oil I’ll beep

Failed iacs as well as many "non critical" sensor faults will cause an intermittent double beep every 2 minutes. Overheats and gear oil monitors will cause a constant alarm

 

[Keymyster]

Good to know.

 

[nowski]

Rsqfxr: Did you use the gasket that came with the Delphi IAC unit or did you use a new Mercury Gasket???

I noticed a difference between the two gaskets so I thought I'd ask...

 

[Shlbyntro]

Thought of something to add. For any of you suffering from a chronic idle surge. Ford built this little known secret for a mustang recall back in the 80s and still produces them

It installs right underneath the iac and gives you minutw idle air adjustments that remove surge.

Ford part number:
F2PZ-9F939-A