DF200 High Idle & Hard Shifts. Idle air control valve issues?

[jserr68594]

I have a 2006 df200 that recently started idling high and consequently shifting hard while at that higher RPM. If I shut the boat off and back on it goes back down to normal idle and then I can shift it normally.

From some quick searching, I've read where the idle air control valve can cause this issue. Does this sound like it might be the cause of my problem or do you think it is something else? Also, should I try cleaning the idle air control valve or just buying a new one? My boat has about 400 hours on it and is fresh water.

I appreciate any input or advice!

[redlowrey]

Sounds like a classic voltage drop problem when cranking, Suzuki and other four stroke engines do not have internal software to compensate for voltage drop, and the usual symptoms are high rpm on start and stall. when you do a restart every thing is ok because the alternator has put charge back into the batteries and brought the voltage up.
Give the batteries a good charge and if the problem is still there do some voltage drop testing before you condemn it.

[jserr68594]

Today I ran a brand new battery connected to my other battery with jumper cables and had the same issues. I am showing 12.8 volts with the engine off and 14 volts with it running. Thanks for the tip though. I ordered a new IAC and am going to replace it and go from there.

[jserr68594]

I just replaced the idle air control motor with the Duralast Mitsubishi brand unit and I still have the same problem.

Any other thoughts? I have had some issues with my neutral safety switch on the motor. I did treat the area where is the neutral safety switch is located on the starboard side of the motor liberally with electrical contact cleaner. I also sprayed spray silicone in that vicinity as well as it is hard to see and I thought that both of those products could do some good. It has improved how often I have problems starting.

The neutral safety switch problem came long before the current high idle issue. Can a failing neutral safety switch cause a high idle?

[redlowrey]

The only thing you have done is checked the open circuit voltage and the charging voltage of the battery, that will tell you nothing about the voltage being dropped across the battery when it is cranking.
Check the voltage at the battery when cranking and note the drop, then do the same at the iac valve on both gray wires and note the drop I bet it is under 10 volts.
And it has nothing to do with the neutral switch.

[jserr68594]

My battery while cranking goes down to 11.20 volts. When the engine is running it is at 14.40 volts. I also did a load test on the battery for 10 seconds and I was showing a little over 1,000 cranking amps. How do my numbers sound?

[redlowrey]

Now do the same thing at the battery pos at the starter, from there at the 60 and 30 amp fuses at the fuse box and the 10 amp fuses, main control relay and ecu. The stepper motor is fed battery voltage via the two gray wires in the wiring plug, the other four are switched inside the ecu. if the voltage is low it won't function properly.

If you can't do this, do this simple test connect your voltmeter to either one of the gray wires at the stepper, turn the key on and note the voltage, then crank the engine and note the voltage drop.