07 496 HO boat with 120 hours- continues to have knock sensor reading and restards motor-new knock sensors and now mecahnic says that its the computer program and is to sensitive-he tried a new Merc updated program but still not solving the issue-says they will try a whipple program $700 and if that does nt worka new computer $2000- does this sound correct? I use the boat little and has been in shop 4 times same issue-in shop now for 1.5 months
07 496 knock sensor computer issue
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[IMHO] I would say no, You should think about finding a new mercruiser service dealer only, That will take the time to find the real problem. Or the shop you are using now should be on the phone with mercruiser tech support as their back up while working on it, With or without warranty, Mercruiser will help a mercruiser service dealer out in finding a problem oneway or another, And if they have called already then have them try a different tech support guy.
It's 100% stock Right???
What City/State are you in???
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11,734 Posts
you could have something as simple as something on the accessory drive of the motor cliking or knocking and the knock sensor will pick it up. has he tried to read the knock sensor with the drive belt off the motor? failed gimble bearing will cause a knock sensor to read false as well
bulbtake it to another dealer, that guy don't know shit.
Their is a few good mercuriser shops out there, Or their is a few out here within your area also. Ask around who is the best 496 shop for hard to find stuff.
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779 Posts
could be the infamous GM piston slap or a rod / main bearing too loose
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4,219 Posts
I would agree that there is something amiss - other than the NEW sensors and the ECM reflash. Buick turbo regals were very "noisy" in the knock department due to the exhaust grumbling via torque moving the engine around and also the long, hot down pipe from the turbo. It would set off the knock sensor all over the place. A fix was to put a ratchet strap on the pass side of the motor - to the frame. Snug the motor down to the frame so it can't move and the knock readings would go away.
If there is something rattling around on the motor or tapping against it during cruise, it would trick the sensor(s).
If there is something rattling around on the motor or tapping against it during cruise, it would trick the sensor(s).
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5,131 Posts
Sounds like you need to find a new shop, these guys are just parts swappers, and thats as far as they will take it. Find a good Mercuiser certified shop / tech, this will get you much closer to finding the root of the problem.
Have run into this a couple times and it turned out to be a bad injector, the injector was not spraying correctly causing the engine to knock. To see if this is the problem engine needs to be run under load with the cds hooked up and 1 cyl shut down at a time to find which one lacks responce.
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308 Posts
Don't know what shop you are using just skimmed the notes real quick but try ROB at Quality performance my bravo was out of warranty in 05 and it discetigrated on the lake he called mercury and they replaced the parts and all I had to pay for was the labor. Tbill was $4100.00 I paid $900.00 He is a higher on his pricing comapered to other shops in the area. But they are good there never ever had a problem. Also had a routine annual service and the person before that worked on it tore a rubber boot in the gimble area and siliconed it back up. He asked who did the service Itold him and it got fixed for free it was also a 300.00 part here is his # 951 735 5503 Rob clarke they are in Corona 2195 railroad Street
Mr HLB
Mr HLB
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