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jmtanlo

IAC problem

12 posts in this topic

Need your advise, I have a 275 SSi 2008 with a 496 mag and this weekend my IAC came in problem. So I did have it check and the mechanic is telling me that due to the failure of the IAC it fry my ECM or computer is damage and I need a new one, is this possible. And no I don't have a filter in under my air filter line that goes to my IAC. Any suggestion Mercruiser is asking $2600. for a new computer.
And by the way where are you now since Gordon Marine is close.

best Regards

JMTANLO
Montreal, Quebec

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Need your advise, I have a 275 SSi 2008 with a 496 mag and this weekend my IAC came in problem. So I did have it check and the mechanic is telling me that due to the failure of the IAC it fry my ECM or computer is damage and I need a new one, is this possible. And no I don't have a filter in under my air filter line that goes to my IAC. Any suggestion Mercruiser is asking $2600. for a new computer.

And by the way where are you now since Gordon Marine is close.

best Regards

JMTANLO

Montreal, Quebec

I'm not saying it's not possible, but I've never heard of a PCM-555 getting smoked just because the IAC burned out. If the PCM sees that the resistance is out of range, it goes zero signal, and alarms. Also, that PCM unit is available here for about 1700 beans. I know it's Canada, but GEEZE...

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After a short search, seems like the PCM failure is not uncommon with a smoked IAC. Seems like there is a repair option out there also.

As Follows:

Unfortunately this is a common problem with the 8.1/496 Mercruiser engines and probably other engine brands as well I can only assume unless it's specific to Merc's 555 PCM's. I'm not sure of that. Typically the IAC gets stuck and eventually melts and in some cases the iac connector will catch fire if not noticed in time. Also the iac driver inside the PCM will short out as well. If the wire harness connector gets damaged, without true confirmation, the new connector harness is rumored to be motorcraft Part # WPT357 seen in post #8, http://www.offshoreo....96-ho-iac.html

Now there is an option vs buying a new PCM. Dennis @ Whipple Industries AKA Whipple Superchargers out of Fresno, CA is able to repair the PCM for less money then new. Information below.

Whipple Superchargers, the performance technology people, can now repair many of the 2001 to 2009 model year 555 ECM and PCM’s used on the Mercury Marine and Mercury Racing engines. Common issues such as the IAC failures and coil driver failures can all be repaired saving you thousands of dollars. No need to spend $2000+ on a new computer, just let the experts at Whipple fix if for you.

This is as simple as removing the ECM/PCM from your engine (3-bolts and 3-connectors), shipping to Whipple Superchargers and within a couple of days, you can have your ECM/PCM back ready to bolt on and go boating. No tuning, no reworking components, no head aches, just bolt on and go.

ECM/PCM repairs for some of the following: 200, 225, 250, 275, 300 XS engines. 135, 150, 175, 200, 225, 250, 275, 300, 350 Verado engines. 4.3L MPI, 5.0L MPI, 350 Magnum MPI (and Horizon), 350 Scorpion, 6.2 MX MPI, 377 Magnum, 377 Scorpion, 496 Magnum Base, 496 Magnum HO, 525HP EFI, 600SCI, 662SCI, 700SCI, 748SCI, 850SCI, 1025SCI, 1075SCI, 1200SCI.


http://www.whipplesu....sp?ProdID=1270

Also there is one other place in CA that does ECM repairs but I'm not sure if he does 8.1's or not, he mainly is an outboard repair shop.
http://www.simonmotorsports.com/

Hope this helps, Good luck.smile.gif

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My Mecanic install a new IAC and no change the computor still rear the same message that the IAC is in failure mode.

So this is why he came to the conclusion that I need a new PCM .

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My Mecanic install a new IAC and no change the computor still rear the same message that the IAC is in failure mode.

So this is why he came to the conclusion that I need a new PCM .

As much as I hate to believe it, he may be right. At least it would seem you have a repair option if you can wait a week to mail your old PCM away. W

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I quest I will have to go with a new PCM, the site that is suggested as no warranty on the PCM and will charge at least 500.00 plus transport, So I will get a PCM from the USA since this where my boat is at this time and is sales foe 1700.00 .

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I quest I will have to go with a new PCM, the site that is suggested as no warranty on the PCM and will charge at least 500.00 plus transport, So I will get a PCM from the USA since this where my boat is at this time and is sales foe 1700.00 .

Make sure you hang on to the old PCM, as it would appear that these things are repairable and as they get older, more repair options may magically appear. It happened with automotive ECM's as vintage ones now can be had for a fraction of what they used to cost.

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Because of this thread, I have purchased a new IAC and will be heading down to the boat this afternoon to replace the old one. At present I am not having any problems with the old one, just preventitive maintenance. Ill keep the old one as a spare just in case. 

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Changed out my old IAC and the old one was original, so Im glad I did it. Ill keep it as a spare. The old one still had the black paint on it. The new one is a chrome colour. Its sunny and warm here today so I will be going out for a cruise to make sure I did it right. ;)

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You should also change the small filter in the body throttle this as to be change or clean every 100 ht the cost is $2.79. This was the cause of my IAC failure .

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