496 help
#11
Registered
Thread Starter
Join Date: Jul 2008
Posts: 225
Likes: 0
Received 0 Likes
on
0 Posts
the alternator is charging fine. Always over 12. Drive fluid is fine, I check it before every time out. Also, all the connections look good, and I have used contact cleaner on all the ones I can see. Next step will be,
- check exhaust manifold sensor
-and the impeller and water pump
Also, I have checked the diagnostic manual and nothing really matches up. Thanks for all the suggestions.
- check exhaust manifold sensor
-and the impeller and water pump
Also, I have checked the diagnostic manual and nothing really matches up. Thanks for all the suggestions.
#12
Registered
Join Date: Jan 2007
Posts: 1,667
Likes: 0
Received 0 Likes
on
0 Posts
the alternator is charging fine. Always over 12. Drive fluid is fine, I check it before every time out. Also, all the connections look good, and I have used contact cleaner on all the ones I can see. Next step will be,
- check exhaust manifold sensor
-and the impeller and water pump
Also, I have checked the diagnostic manual and nothing really matches up. Thanks for all the suggestions.
- check exhaust manifold sensor
-and the impeller and water pump
Also, I have checked the diagnostic manual and nothing really matches up. Thanks for all the suggestions.
If it's missing, it will race at medium idle in or out of gear and will go away above 1200.
That's its job - to prevent varying engine speeds in the range you are talking about.
#13
Registered
Join Date: Jan 2007
Posts: 1,667
Likes: 0
Received 0 Likes
on
0 Posts
With regards to the beep, why don't you graph the various parameters and time it with the engine rev?
You may find it that way.
Is the reving fairly consistent? If left in neutral, will it race or rev about the same amount of time every time?
Regardless of how broken up or bound up the impeller could ever become...... There is NO WAY that engine would ever "feel" or notice that type of load. It would idle as normal as no small piece of veined rubber could ever change the rpm of that engine.
You may find it that way.
Is the reving fairly consistent? If left in neutral, will it race or rev about the same amount of time every time?
Regardless of how broken up or bound up the impeller could ever become...... There is NO WAY that engine would ever "feel" or notice that type of load. It would idle as normal as no small piece of veined rubber could ever change the rpm of that engine.
#15
Registered
Join Date: Jan 2007
Posts: 1,667
Likes: 0
Received 0 Likes
on
0 Posts
Run it under load with the scanner and graph the sensors.
Check plugs, wires etc. It's real hard to troubleshoot on the internet.
What Merc Scan tool did you use? The DDT can be too slow for certain issues. The symptoms can fall between the refresh rates...
Get someone to help you locally. Good luck -
#17
Registered
if I remember correctly there is a ground stud on the back of the block that is hidden under the water hose that runs across there, my stud was all corroded and those ground wires weren't making a good connection. I sold my boat a few years ago but I think I am remembering it correctly it was a 2002 28 daytona with 496's
#18
Registered
Thread Starter
Join Date: Jul 2008
Posts: 225
Likes: 0
Received 0 Likes
on
0 Posts
ok gentleman, ran the boat today and have a update. First the foam was missing, and a new piece fixed the rough idle, and extra noise i had. Sweet. But, I still get and a temporary surge in rpm any place under 1200 rpm with a beep. It sounds just like when you start the boat from key off. Also, it died a few times at idle when shifting. Any suggestions? Thanks for all your help.
#19
Registered
Join Date: Jan 2007
Posts: 1,667
Likes: 0
Received 0 Likes
on
0 Posts
ok gentleman, ran the boat today and have a update. First the foam was missing, and a new piece fixed the rough idle, and extra noise i had. Sweet. But, I still get and a temporary surge in rpm any place under 1200 rpm with a beep. It sounds just like when you start the boat from key off. Also, it died a few times at idle when shifting. Any suggestions? Thanks for all your help.
FYI - the foam is to prevent a slight & consistent engine race; it does not have anything to do with a "rough" idle but you will notice a difference without it for sure.
#20
Registered
Thread Starter
Join Date: Jul 2008
Posts: 225
Likes: 0
Received 0 Likes
on
0 Posts
496
ok new update. Purchased the diacom software to help solve my problem and still cannnot trace it down. The problem engine still does the surge. It is worst at 1000 rpm. At that rpm it will surge and throw a warning beep almost every four or five seconds, its just like when you first start a engine. It will beep, rev up, then come down again. Just like the ecm resetting? I scanned it multiple times, one time it threw map hi, crank sensor, and cam sensor codes, but after clearing them and running again with same issues no codes after? Also, after about 40 minutes of using the diacom software the ecm would not connect to the diacom software anymore so i am stuck for now.
Thanks for all the time and help so far guys, I appreciate the help. Also, this is a idle to 1300 rpm issue only. Fine running above 1500. Sorry about the long post..
Thanks for all the time and help so far guys, I appreciate the help. Also, this is a idle to 1300 rpm issue only. Fine running above 1500. Sorry about the long post..