496 quit on power reduction
12-17-2015, 07:20 PM
#11
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^^^^
i have been searching this for the past hour or two now. seems like just like everything else proper maintenance makes the part last longer. one question i do have now is, i see where many people say pull the foam muffler out, and it will save the IAC as well. seems to me that it would keep dirt from getting in the IAC? what is your thought on that?
i have been searching this for the past hour or two now. seems like just like everything else proper maintenance makes the part last longer. one question i do have now is, i see where many people say pull the foam muffler out, and it will save the IAC as well. seems to me that it would keep dirt from getting in the IAC? what is your thought on that?
12-17-2015, 07:40 PM
#12
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Completely wrong info. And who said that ??? I will post more later - I do have a really good post up here about the duty cycle,
The very first 496's did not have a IAC muffler and there was a reason for it, then Merc did a campaign recall for those 496 PCM's. One was for soot and emissions / to meet the emission star ratings set by the EPA compliance. I will try to find the post also.
See Merc did a recall on the 496 PCM and when you got the PCM back the IAC MUFFLER was taped to the PCM as they incorp it with the new recal of the PCM. Believe me I know all about and the reasons why after the first year maybe first 1.5 years of the 496 in production - all of them had this recall campaign.
The very first 496's did not have a IAC muffler and there was a reason for it, then Merc did a campaign recall for those 496 PCM's. One was for soot and emissions / to meet the emission star ratings set by the EPA compliance. I will try to find the post also.
See Merc did a recall on the 496 PCM and when you got the PCM back the IAC MUFFLER was taped to the PCM as they incorp it with the new recal of the PCM. Believe me I know all about and the reasons why after the first year maybe first 1.5 years of the 496 in production - all of them had this recall campaign.
Last edited by BUP; 12-17-2015 at 07:43 PM.
12-17-2015, 09:21 PM
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Completely wrong info. And who said that ??? I will post more later - I do have a really good post up here about the duty cycle,
The very first 496's did not have a IAC muffler and there was a reason for it, then Merc did a campaign recall for those 496 PCM's. One was for soot and emissions / to meet the emission star ratings set by the EPA compliance. I will try to find the post also.
See Merc did a recall on the 496 PCM and when you got the PCM back the IAC MUFFLER was taped to the PCM as they incorp it with the new recal of the PCM. Believe me I know all about and the reasons why after the first year maybe first 1.5 years of the 496 in production - all of them had this recall campaign.
The very first 496's did not have a IAC muffler and there was a reason for it, then Merc did a campaign recall for those 496 PCM's. One was for soot and emissions / to meet the emission star ratings set by the EPA compliance. I will try to find the post also.
See Merc did a recall on the 496 PCM and when you got the PCM back the IAC MUFFLER was taped to the PCM as they incorp it with the new recal of the PCM. Believe me I know all about and the reasons why after the first year maybe first 1.5 years of the 496 in production - all of them had this recall campaign.
i want to take every precaution i can to ensure my new boat lasts a long time without any type of issue. i already have a second battery going in, with a switch. to ensure proper voltage is always available.
Last edited by RGPIII; 12-17-2015 at 09:23 PM.
12-17-2015, 10:13 PM
#15
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^^^^^^ IAC muffler is a replacement item whether anyone likes it or not. Once or twice per year and you need to cut down on the belt dust so the serp belt is very important and its tension along with true running line up (alignment of the belt needs to be very true) . Everything needs to be kept cleaned is important and I already mentioned some of the items that needs to be cleaned.. Like I said I have customers with 496 Mercs with over 10 plus years on the same IAC. Why because I properly maintain for it. Yes its cost money to do so and I charge for it.
12-17-2015, 10:26 PM
#16
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Matt we did that way back when the IAC become a big failure rate. 2004 or 2005 - timeframe ??? anyways it was the same old tune - IAC failures and they kept on increasing. One of the reason was because owners had incorrect belt tension from the adjuster bolt after removing the belt for Impeller changes. The improper tension cause alot belt dust over time. Plus not many new about the installed IAC muffler and it became completely clogged. Not many back then changed it nor seen where it was. Even some techs back then did not know about it.
What I did was more of way to see and play around with it. We blocked externally the fitting off / TB - then cut a hose to match and attached that along with a crankcase breather off the IAC block. We went to the lake all day with it. Things noticed right away - was the idle surged - we liked it but did not like it. Kind of a lumpy cam engine at idle and sound persay but not a smooth idle for docking. Next negative - it produced a louder hissing and noise than stock set up.
The PCM calibrations has changed in the later years along with the change in CRANK - X. I never tried it again after that one time with the crankcase breather nor scanned the engine. That was probably a mistake on my part not scanning it..
I will say that you need for a good range about 24 to 34% pulse width modulation from the IAC at idle from a fully warmed upped engine OEM COMPLETELY STOCK 496 Merc. I like 30 % the best in a real world but that will never stay perfectly steady. 30 % basically - thats were Merc moved up the PWM with the newer cal.
What I did was more of way to see and play around with it. We blocked externally the fitting off / TB - then cut a hose to match and attached that along with a crankcase breather off the IAC block. We went to the lake all day with it. Things noticed right away - was the idle surged - we liked it but did not like it. Kind of a lumpy cam engine at idle and sound persay but not a smooth idle for docking. Next negative - it produced a louder hissing and noise than stock set up.
The PCM calibrations has changed in the later years along with the change in CRANK - X. I never tried it again after that one time with the crankcase breather nor scanned the engine. That was probably a mistake on my part not scanning it..
I will say that you need for a good range about 24 to 34% pulse width modulation from the IAC at idle from a fully warmed upped engine OEM COMPLETELY STOCK 496 Merc. I like 30 % the best in a real world but that will never stay perfectly steady. 30 % basically - thats were Merc moved up the PWM with the newer cal.
Last edited by BUP; 12-18-2015 at 12:52 AM.
12-19-2015, 11:50 PM
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Pulled the arrestor yesterday and the muffler and throttle plate were filthy. The IAC has been replaced it looks like. The muffler looked original. cleaned the arrestor pulled the muffler to replace and cleaned the throttle plate.
