I Have Gotten A High Pitch Sound Coming From My 525 Efi. The Rpms Came Up About 600rpm And I Assumed It Was A Vacum Leak. I Took It In To The Deaer And It Showed No Codes On The Computer And They Could Not Pin Point Any Leak. They Have Been Talking With Mercury Racing Butno Luck Yet. The Sound Is So Loud That They Are Wearing Plugs When Engine Fired. Anybody Heard Or Had This Problem?

could be the IAC (idle air control ) will cause idle to increase and sounds a little high pitched, have your dealer check the setting and if he has the cds system he can test it also to see if that is what you are hearing....
what area are you in?????

i'm in tulsa oklahoma. i took it back to the dealer since it is underwarranty but he says it is not setting a code. i would think that a iac would set a code in the computer.

it sounds like the IAC is open too far. Your dealer can check the IAC position with his scanner. This situation does not always set a code. One thing to keep in mind though is that most of the time this is a response by the ECM to another problem. I'm not sure what the normal IAC range is for the 525 and it's not in the manual. Your tech will have to call Merc to get that info.

i dont know if this may help but we had a 500 efi that was making a high pitched whissle (this may be what you are describing maybe not) but it ended up being the breather tube coming from the vavle cover up to the air cleaner (it is actually made of wire loom you can buy at any electronics store) and mercury actually makes a small piece of foam you stick in the tube and that solved our problem but like i said i dont know if this is what you are trying to describe or not

M boss just put a pair of 525's in his 357 and is complaining about a high pitch whistle and it's driving him crazy but as far as the idle goes it idles normal.When you say the idle came up 600 rpm does that mean it idles at 1200?

IAC wont away set acode,only when it is bad not when it is just out of adjustment,alot of dealers dont know the smart craft system that well take it to a performance dealer that sells alot of 496s and 525s though all dealers sell them most of there sales are still small bocks or there mechanics give up to early and if the computer doesn't scream something at them they say all is well !!!

merc now makes a little k&n filter for the breather that u are talking about

that is what the mechanic told me it was on the phone before seeing it, but the 525 is not the same set up is the 500. so now he is stumped.

it came up in neutral to about 1200 than after a day of use it went to 1600.