DF 225 IAC valve

[JWSVirginia]

Hope someone can help me. My IAC valve went bad on my 2009 DF225 outboard. Bought a new one from the dealer and put it on. Engine starts, but idles around 1000rpm. Is it typical to have to adjust the idle speed after installing a new IAC valve? Or could I have gotten a faulty valve. The dealer did not give me a Suzuki OEM part, it was another brand. Thanks.

[UrbanBatic]

First take a multimeter in your hands and measure the resistance between the 6 terminals.

IAC valve
motor
1 2 3
4 5 6

So, turn the IAC valve with terminals up to you and they should be below the IAC motor.
If I recall it right, you should measure the resistance between 1-2, 2-3, 4-5, and 5-6. In all 4 cases, you should get 25-34 Ω (Ohms). Any of them off by just a little and you know that you have a faulty part. I had 2 pairs messed up showing 2,5 and 4 I think.

If all that is OK let's move to another thing: Adjusting the idle speed (copied out of manual).
ADJUSTMENT:

If engine idle speed is out of specification, the following adjustment procedure must be performed.

1. Shift into Neutral and close the throttle fully (this will cause the fully close throttle signal to be input to the ECM).

2. To set the IAC valve duty to constant 30%, turn the ignition key from ON to START five times within ten seconds.
At this time, caution buzzer will sound to notify that IAC duty is in fixed mode.

NOTE:
• The ignition key operation to set the IAC valve into the fixed mode should be performed with the engine running at idle.
• While IAC valve duty is at a fixed 30% duty, the caution buzzer will sound in a repeating pattern of 0.5 seconds on with an interval of 3 seconds off.
• The 30% fixed mode of IAC valve duty will continue for 5 minutes after which it will automatically cancel.

3. During this fixed mode of IAC valve duty, adjust engine speed to 650 ± 50 r/min. by turning by-pass air screw.

Turning air screw counterclockwise: Engine speed will increase.
Turning air screw clockwise: Engine speed will decrease.

4. When finished adjusting the idle speed, opening the throttle will automatically cancel the IAC fixed mode.

NOTE:
The fixed mode of IAC can also be canceled manually by shifting to Forward or Reverse or raising the engine speed (causes the fully close throttle signal of TPS to be OFF ).

5. Return the throttle to full close and check engine speed. It should now be stable at 600 – 700 r/min.

NOTE:
Idling/trolling speed of 600 – 700 r/min. is controlled by IAC (idle air control) system.
If engine speed does not return to specification, IAC passage may be clogged or IAC system may not be operating correctly.

NOTE:
Trolling speed (in-gear idle speed) is same as idle speed.

[JWSVirginia]

Thanks for the reply. I did not check the resistance, but followed the service manual (I have one) for adjusting the idle speed and it would not slow the idle down at all- even with the air screw all the way closed. I called two mechanics and was told that the engine needed to be hooked up to the computer with Suzuki software to reset the idle control valve and idle speed. So I trailered it 2 hours to the nearest Suzuki service center. Thanks again.