F 115 issue

[jeremy5780560]

My 2005 F115 has started doing something strange. I just pulled it out of the water for service,waterpump, plugs, thermostat and cleaned the IAC. The motor idles at 800 RPM and purrs like a kitten but if you put it in neutral and rev it up and back to neutral real quick say from 800 RPM to 1500RPM on the way back to idle the motor wants to stall out but doesn't. It only does this when you rev it up and back real quick, if I just rev it up and back steady its fine. Any ideas?

 

[tommarvin]

A wild guess, the idle jets are dirty, an ignition part is failing slowly, it's not broken yet, an air leak

 

[flyingscott]

Is the motor new to you and does it do it on muffs or in the water. Is the motor carb or EFI

 

[jeremy5780560]

Motor if EFI I have had the motor about a year and a half now and it just started doing this a couple months ago, it does it both in the water and on the hose. It started doing this about a month ago followed by idling low like 4-500 rpm I pulled the boat out of the water and got it to idle at 750-850RPM by turning the screw under the plastic cover on the side of the motor just under the TPS about a 1/4 turn. I also plugged the motor into the Yamaha diagnostic system and there were no codes or issues. I guess there is no Real big issue yet, I was just wondering if there was a similar issue somebody had so I could get this Yamaha running like new again.