DF140 IAC Valve Error Code 3-1

[macedonia]

We went out cruising on Saturday. When leaving the dock I noticed that the starboard DF140 was not running. I restarted it without a problem. No error code. It had just stopped running.

We cruised at around 25 knots, going to idle then back to cruising speed several times with any problems.

On about the 5th or 6th time going from idle to cruising the starboard engine would not go past about 3000 rpm. I slowed to idle and saw the 3-1 error code which the service manual shows as IAC valve/By-pass air screw adjustment.

Thankfully, we have twins so we returned on the port engine at about 5 knots.

Questions:

1. Does this typically result in replacing the IAC valve?
2. If adjusting the By-pass air screw adjustment, is an external engine tach required?

Any other thoughts on how to diagnose the problem or bad IAC valve? I don't won't to replace unnecessarily.

Thanks,
Nick

[catacom225]

Hi Nick
I had a similar Issue, pick up a used IAC from a 2 liter suzuki serra for $30 replaced it but still had an error code. Went through the air idle adjustment procedure and code was gone, Not sure whether the valve was faulty or not i took it to my Auto Electrician friend and he confirmed with out any doubt the IAC valve was not working. 4 years now with no issues

[macedonia]

What is a Suzuki Serra? The cost of a new DF140 IAC valve is about $300. $30 sounds really good.

Since you used the idle adjustment procedure, you must have used an external tach connected to the ignition high tension cord.

What make and model tach do you recommend?

Thanks,
Nick

[Muskykris]

If you decide to change the iac do it yourself... Super easy

I'm having trouble with my 115 and I just removed it 20 minutes ago.

Remove left/port lower cowling
Remove air box and it's sitting above throttle body.
2 10mm bolts holding it on and a quick disconnect for the electrical.

Kris

[Moonlighter]

If you get the part number, you will find that it is made by Mitsubishi, if memory serves me correctly. It is commonly used on cars from various manufacturers.

You can then search for that Mitsubishi part number and get either a genuine Mitsubishi one from a auto parts supplier, or a non-genuine copy from parts suppliers or sources on ebay. Both are much less expensive than buying thru Suzuki Marine. Google is your friend!!

(By the way, a Suzuki Sierra is a small 4WD car!)

[macedonia]

Thanks Kris - that's encouraging. I do plan to replace it myself.

Nick

[Muskykris]

Google or Amazon

Delphi cv10084 idle air control valve

$49

Looks identical, I'm just not 100% sure if the electrical connection is the same
https://www.amazon.com/Delphi-CV1008.../dp/B000CGDCZM

I took the chance

Kris

[Muskykris]

It appears after looking at a bunch of pictures the plastic on the electrical connection could be a touch different. I may have to shave the guide tabs off and apply a dab of glue or silicone to hold it in place.

I'll let u know in a few days how I make out

[catacom225]

Sorry not a Suzuki Sierra but a 2 litre Vitara

[Muskykris]

Update on the $49 part off amazon

So the body of the valve is 100% match

The electrical connection was completely different .

I cut the plastic off around the 2 prongs... Now it plugs in fine

It holds fine just with the 2 prongs sticking into the female connection.... But I'm going to add a dab of silicone or super glue to hold it better

Knowing this peice only effects idle, I'm not worried about it leaving me stranded

Kris

[norrisga]

How's the $49 Amazon part working out? I'm having the same issue and don't want to spend $240 for the suzuki part.

Thanks

[norrisga]

So I bought the $59 car IAC from amazon, modified the plug and installed it on my 2002 DF 140 that wouldn't start w/ the throttle in the closed position and was giving a 3-1 code.

I then went through the idle speed adjustment procedure from the service manual. The code cleared and the engine now runs fine. The issue is the 3-1 code keeps coming back intermittently. it comes and goes randomly but the engine cranks and runs fine. I've done the idle speed adjustment 3 times but not sure about the CTP references:

"4. Check that CTP switch is in ON position."

"7. Open warm-up lever to turn CTP switch off"

How do I check that the CTP is ON?

Is opening the warm-up lever just moving the throttle forward?

Any ideas on how to make the code go away and not come back?

Thanks