Running Out of Ideas / 2006 twin 496 MAGs
03-15-2018 | 08:48 AM
#11
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Joined: Feb 2004
Posts: 2,590
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From: Endicott, NY
Yes, IAC does not often show codes, and is usually the culprit on these idling situations. And quite often sometimes you think they are fine but it has to do with the ambient temperature, cold start, warm start, fish swimming by, girl in bikini...ect. Then you install a new one and it does the trick instead of the searching noise and fluctuations that you will find when its trying to zero in on the correct counts. Good luck, hopefully keeping it simple will pay off
03-15-2018 | 06:06 PM
#12
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From: Tygart Lake, WV
Thanks to all..
Im responding to the last three responses.
I do not have any way of getting the IAC Pulse Width data that I know of. While I have "vessel view mobile" and can see error codes, I do not have a full read capability for all data. (Or am i missing something?)
I will check the fuel rails for rust/ oxides and still have the injectors in mind for a cleaning. This would be the time to look for rust. However the engines run well at high RPMs and as a result I had stopped thinking about fuel as a source of issues.
I had pulled the tank pickup and its in fine shape. Sealed the joints with a seal compound.
I have clean fuel filters in both engines and missed the chance to dissect the old filters.
Since changing the IAC (PORT) the cold start issue is less pronounced. It still takes some throttle for the first 10 seconds for a high RPM idle. After that it idles fine. Strikes me that the engines are not heating up or at lease not by much in the short time.
I still plan to check the TPS for a dead spot - I may just swap PORT and STBD - TPS. I also am taking the advice of you all and changing the IAC for STBD.
Again thank to all for the advice and constant ideas.
Al the Best;
Vince
Im responding to the last three responses.
I do not have any way of getting the IAC Pulse Width data that I know of. While I have "vessel view mobile" and can see error codes, I do not have a full read capability for all data. (Or am i missing something?)
I will check the fuel rails for rust/ oxides and still have the injectors in mind for a cleaning. This would be the time to look for rust. However the engines run well at high RPMs and as a result I had stopped thinking about fuel as a source of issues.
I had pulled the tank pickup and its in fine shape. Sealed the joints with a seal compound.
I have clean fuel filters in both engines and missed the chance to dissect the old filters.
Since changing the IAC (PORT) the cold start issue is less pronounced. It still takes some throttle for the first 10 seconds for a high RPM idle. After that it idles fine. Strikes me that the engines are not heating up or at lease not by much in the short time.
I still plan to check the TPS for a dead spot - I may just swap PORT and STBD - TPS. I also am taking the advice of you all and changing the IAC for STBD.
Again thank to all for the advice and constant ideas.
Al the Best;
Vince
https://www.offshoreonly.com/forums/general-boating-discussion/351552-fuel-injector-maintenance.html
03-15-2018 | 06:28 PM
#13
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From: Ft. Worth TX
04-03-2018 | 12:38 PM
#14
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Problem solved - Almost
Well Thanks Everyone
I changed out the IAC on the Port engine and listening to Port vs Starboard checked all of the coil packs with no findings. I then started pulling plugs and guess what I found? One cold (dark) plug with cracked ceramic.
With a couple new plugs as I broke another, the boat starts fine and idles fine. Yahoo! Now the next mystery.
I'm still trying to understand why one engine purrs at 3K RPM while the starboard engine roars. Is there any way that the timing is off?
Thanks All
I changed out the IAC on the Port engine and listening to Port vs Starboard checked all of the coil packs with no findings. I then started pulling plugs and guess what I found? One cold (dark) plug with cracked ceramic.
With a couple new plugs as I broke another, the boat starts fine and idles fine. Yahoo! Now the next mystery.
I'm still trying to understand why one engine purrs at 3K RPM while the starboard engine roars. Is there any way that the timing is off?
Thanks All
04-03-2018 | 02:24 PM
#15
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Joined: Jun 2011
Posts: 2,169
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From: Henderson, KY
If all of this headache (including replacing the spark plugs - item #1 in your list) was over a cracked spark plug, you need a new mechanic.
1) New plugs : They old ones were in terrible shape but no real improvement. (cause he cracked one putting the new ones in ?? ...and didn't confirm his work??)
Sometimes, (quite often) - its not the "computer", nor are there magic codes out of said computer, that tell the mechanic what to do. Basic problem solving is needed. Got to have suck, squeeze, pop, fooey - or no bueno.
Sorry, I'm in a mood today - not your fault. :-)
1) New plugs : They old ones were in terrible shape but no real improvement. (cause he cracked one putting the new ones in ?? ...and didn't confirm his work??)
Sometimes, (quite often) - its not the "computer", nor are there magic codes out of said computer, that tell the mechanic what to do. Basic problem solving is needed. Got to have suck, squeeze, pop, fooey - or no bueno.
Sorry, I'm in a mood today - not your fault. :-)
04-27-2018 | 07:51 AM
#17
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I found the guilty mechanic and its me. 
I had trouble originally reaching the plugs towards the back and I'm certain it was me that cracked it. Overall the two engines are now twins as they should be. Start the same and purr when throttled up. I have one more strange but very minor issue.
Starboard - one turn of the key and she's running with no burps or sputters.
Port - first turn of the key and she starts and then dies in two or three seconds. However on second turn of the key she's running just like the Starboard.
Of course this is a very minor and inconsequential issue. When I first began working this you had to advance the throttle to keep it running while cold.
I also fixed a belt noise issue - see related post. 496 Mag / no more belt noise
Take Care
Vince
I had trouble originally reaching the plugs towards the back and I'm certain it was me that cracked it. Overall the two engines are now twins as they should be. Start the same and purr when throttled up. I have one more strange but very minor issue. Starboard - one turn of the key and she's running with no burps or sputters.
Port - first turn of the key and she starts and then dies in two or three seconds. However on second turn of the key she's running just like the Starboard.
Of course this is a very minor and inconsequential issue. When I first began working this you had to advance the throttle to keep it running while cold.
I also fixed a belt noise issue - see related post. 496 Mag / no more belt noise
Take Care
Vince
07-15-2018 | 06:28 PM
#18
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Hello All
Long time no post. I invested in a Rinda Techmate Pro. Within a few minutes I found that Cylinder #7 was not firing. Ruled out compression, spark, spark wire and plug. I just installed new injectors ( 8 each totaling $300) and as I pulled #7 injector I found the fuel rail to be full of rust particles and the injector was clogged. I clean ed out the rail and have the new injectors in working well. The engine starts with a single key click and purrs. I plan to send the injector out for cleaning and use them for the Starboard engine. The Techmate Pro was worth every penny.
Take Care
Vince
Long time no post. I invested in a Rinda Techmate Pro. Within a few minutes I found that Cylinder #7 was not firing. Ruled out compression, spark, spark wire and plug. I just installed new injectors ( 8 each totaling $300) and as I pulled #7 injector I found the fuel rail to be full of rust particles and the injector was clogged. I clean ed out the rail and have the new injectors in working well. The engine starts with a single key click and purrs. I plan to send the injector out for cleaning and use them for the Starboard engine. The Techmate Pro was worth every penny.
Take Care
Vince
07-15-2018 | 11:42 PM
#20
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Joined: Jul 2011
Posts: 9,594
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From: Ft. Worth TX
Possible warning here --- china knock off injectors if they were new and bought online. that is just over a hair 35 dollars per injector. NO WAY these are OEM injectors. Distributor pricing is more than that and their buy ins are alot of injectors in the 1000 s. I bet you got your deal online for the knock offs. Reman OEM injectors are more than that.
And some of you guys seen my videos of the china knock off injectors when I tested them. Half OEM and half china town injectors tested at the same time. Spray patterns and volumes totally different.
And some of you guys seen my videos of the china knock off injectors when I tested them. Half OEM and half china town injectors tested at the same time. Spray patterns and volumes totally different.
Last edited by BUP; 07-16-2018 at 12:22 AM.
