Mercruiser Mpi fault code 152 ?

[QBhoy]

Guys
Towards the end of a lovely day out (in a rare 26oC Scottish Loch Lomond trip) a fault code beep raised its ugly head.
2 short beeps every minute exactly.
The vessel view mobile app has shown a few of he normal codes, but I'm pretty sure the most recent fault code isn't normally there. It is fault code 152.
When sitting at 2400 rpm and around 26mph the 2 beeps every minute where constant and routine.
All analogue pressure and temps were fine.
When under more throttle, it seemed that a safe mode kicked in at around 4000rpm and then the beep was a constant.
I stopped the boat again (for the 4th time) to check gear oil header level, oil level, manifold and riser temps. All seems fine.
Any hints or clues or what the 152 fault is ?
Thanks guys.

 

[tpenfield]

Google is your friend . . .

seems to be an IAC Fault.

 

[QBhoy]

Tpenfield
I've googled the B'jeesus out it...all seems very secretive. I can't find a definitive fault code list at all. Just assumptions and ideas.
Did you see that 152 code indicates this ?
Thanks for the reply. Appreciated !

 

[alldodge]

Does appear 152 is the IAC but what are the normal codes you see all the time?

2 beep codes can be several other then then ones you mentioned, and the 2 beep and then going to constant beep at 4K rpm's I would think its the seawater pressure switch

 

[QBhoy]

Hi alldodge, was hoping you would turn up !
The normal fault codes are ones that my engine doesn't have sensors for in the first place, so it shows the same faults as standard every time.
The 152 seems to be new. Not 100%, but pretty sure.
I've tried to attach a screen shot from the vessel view.
If it was an IAC fault, he symptoms would surely be a poor idle and perhaps not running at all. All seemed perfect, apart from the beeping.
The SW pressure switch, how would I test this ? Totally new to this mpi nonesense.
You would think that Mercury would just publish a definitive fault code list. I have seen the info you posted but struggle to make too much sense of it...perhaps it's just me !

 

[alldodge]

Code 75 - Fuel level circuit high
Code 94 - Pitot circuit high
Code 119 - Stear circuit low
Code 130 - Trim circuit voltage high

These can be cleared by going thru the menu and doing a reset. Need to go back thru the menu until you find the circuits and tell smartcarft there not there, either that or live with it like you have been doing.

The 152 needs to be figured out, but since your not getting SW code then it may not be it. The SW switch is located on the power steering cooler. The list of constant beeps are in the pic above

 

[QBhoy]

Thanks all dodge.
Yeah, it's just the 152 I can't figure.
Perhaps confession time. Just remembered that I put 10 litres of fuel in that was mixed at 50/1 2 stroke oil. I also put in another 50 litres of straight 98 octane rating petrol to dilute it. Surely this would be ok ? I often do this because of the ethanol issue and lack of natural lubrication on fuel these days.
Perhaps the MPI is a touch sensitive to this ? One would think that the 2 stroke would be well diluted though. All the fuel was out in at he same time.

 

[QBhoy]

Clean the air mass flow sensor maybe ?

 

[Bt Doctur]

152 Idle Air Valve

 

[QBhoy]

Thanks

 

[tpenfield]

Tpenfield
I've googled the B'jeesus out it...all seems very secretive. I can't find a definitive fault code list at all. Just assumptions and ideas.
Did you see that 152 code indicates this ?
Thanks for the reply. Appreciated !

Yes, 152 does not seem to have much documentation. I found several forum posts and the like that indicated 152 was the IAC. If the truth be told, I have gotten lazy in my old age and now have the computer program that I just plug into the engine to get the codes and the engine parameters

 

[QBhoy]

Thanks TPenfield. I'll have a look at the iac and filter. None of the expected symptoms of it though.

 

[Fun Times]

Clean the air mass flow sensor maybe ?

Not a big deal but just as an FYI if interested... Mass Air Flow Sensors are mostly found on most (Not All) newer automobiles with fuel injection. Your Merc engine uses what is know as an Speed Density System which uses a MAP (Manifold Absolute Pressure) sensor among some other sensors to help calculate Air/ Fuel Flow Measurements. http://www.xcceleration.com/sd-vs-maf.htm

Since you are showing a 152 fault code which is part of the IAC (Idle Air Control valve/motor) and getting the warning horn, that is the system you'll want to concentrate on as even though it might not necessarily seem like it'd be an issue because you're seeing odd things happen above idle RMP's and not necessarily at idle RPM? (Correct??) (< Meaning idle RPM fluctuations to where the engine is/almost stalling, rough idle speeds, things of that nature)...You're just getting a code and warning horn only.. correct? Or are you seeing other symptoms too at all RPM's?

With the newer designed engines like yours, I have noticed that there have been other boaters out there that have mentioned experiencing the same sort of symptoms as you seem to be having at higher RPM. Which again could seem odd as sometimes the IAC symptom fault codes may show up when you'd think it would not have any affect on the engine unless you were only at idle speed being it's called an "IAC".

Some things that have been know to possibly set off an IAC warning horn/fault code could be a dirty and or missing IAC foam muffler, carbon dirty IAC valve air passage hole systems, dirty throttle body inner housing / plates, faulty IAC valve motor, faulty/dirty wiring connectors, too high or low on 12 volt power on the entire IAC system or a faulty IAC drive found inside the ECM....If the ECM becomes suspected as it's getting kind of common to read about online nowadays, there is a place in California you could mail the ECM into for inspection + repairs vs buying a whole new ECM. $600.00 for actual repairs vs $1,500.00 + for new.

Check the IAC motor/wiring for excessive signs of heat too.

 

[alldodge]

I hear others mix some 2-stroke every now and then, and while it probably may not bother things, it could have an effect that is unexpected. If some how it caused one injector to lean out there goes your motor. The modern motor is designed for the E10 so there should be no issues using it.

I'm not 100% sure but I don't think smartcraft shows all faults. Would be interesting if a scanner would show something that it didn't.

 

[QBhoy]

Fun times
This is excellent (apart from the expensive worst case scenario bit )
I'm going down to the boat later to have a look at the iac filter and perhaps I'll buy a iac gasket, take it off for a clean out too.
Yeah, you're right about it....no other physical symptoms apart from the beeping then constant beep and seemed to limit at around 4000 rpm. No rough idle or starting problems.
I'll post what I find later.
Thanks again all. Alldodge too

 

[Bt Doctur]

Never had these kinds of problems with carbs

 

[QBhoy]

Hi Took the IAC off today...looks as if it's original but perhaps had been off before. Local Merc dealer reckons some folk keep a spare on the boat, because they are known to fail that often. Also suggested that the unusually high temperatures get in Scotland wouldn't have helped with the boat running for a sustained period of time. Apparently they are mechanically and electrically weak components. I was warned about the MPI ! Great when they are running but electrically problematic ! Anyway, ordered a new IAC....see how we get on ! Thanks for all the help guys.

 

[alldodge]

They do go bad, but for all the 100's of thousands that are out there, they really don't fail that often. The one which had a lot of issues was the early years of the 496's. Hope it fixes the issue

 

[QBhoy]

Thanks Alldodge

 

[QBhoy]

New IAC fitted yesterday....fixed the problem ! Delighted and thanks for the help all....
Impressed with the wee vessel view Bluetooth mobile device telling me the fault code !