DF140 3-2 Code - Not the Corrosion Issue

[ssbogger]

Hello all,

My 2001 Suzuki DF140 started stalling at idle, running rough, would not go over 3k rpm and showed a 3-2 code last October. I've read through multiple looking for a solution to no avail. Motor has 140 hours on it. At first I was convinced it was the corrosion issue but that has not been the case.

What I have looked at:

1. Pulled the cowling and started the motor. It still throws the code and is hard to start. Turns over fine but I have to give it some throttle to actually start. Once it starts a few times I can get it to idle but it is really rough and there is a good bit of soot in the exhaust water.
2. Pulled the side covers to check for corrosion. The exhaust port plug unscrewed just fine and there are no signs of corrosion. I even went so far to spray the motor down with soapy water while running to see if I could see any leaks. None apparent. Again, it still shows the symptoms with the cowling off.
3. Pulled, inspected and cleaned the MAP sensor.
4. New spark plugs, fuel filter (not the high pressure), oil and filter change (it was due), impeller (it was due).
5. None of this helped,

Took it to Mechanic #1:

1. He pulls and tests injectors. Says they are good.
2. He tells me its a bad wiring harness and that the whole motor just needs a thorough tuneup. I didnt have a good feel about the guy and he wanted me to buy parts and bring them to him. He lived an hour away and I wasn't going to be driving back and forth to do this. I picked the boat up with no resolution.

Took it to Mechanic #2:

1. They installed a new MAP sensor. No change in the motor.
2. Check the gas. No water in it.
3. Checked for corrosion. None found.
4. Checked injectors. They are good.
5. Did a leak down test (i think thats what its called). All good.
6. Says that the plugs are getting really black but they are all getting the same amount of black.
7. Swapped the ECM from a Johnson. Says it cranked right up and idled smooth. He said it did throw an oil light when he did this but the code did not show up

At this point, Mechanic #2 has recommended that I get a new ECM. Of course I am hesitant to do this with it being so expensive so I have a few questions for you all.

1. I have not checke the IAC valve. Mechanic 2 says that if this was the problem then I wouldn't have had the issue of not being about to get past 3k RPM.
2. Does a bad ECM sound like my problem?
3. If it is a bad ECM, what are the chances that the new one will develop the same problem?
4. Is buy a used ECM a smart option?

Thanks in advance for the help. I really need to get this resolved. It's been a tough summer telling my wife that we cant go on the boat weekend after weekend...

[Solarman]

You have 140 hrs on a 17yr old motor? Not a lot of use, sounds like it sits up a bit?

I would check neutral safety switch on engine (could be sticking (limit to 3k rpms), and have the IAC checked out/ cleaned (could cause 3-2 map code) if dirty and not working smoothly.

Just some/my thoughts.

Good luck, post back when able to let us know.

[henpecked]

I know you say it’s not corrosion but i just finished repairing mine which was exhibiting the exact same symptoms and throwing the same code. Actually a throttle valve which was corroded. 2017 300 with 150 hours. Not happy about the corrosion issue this early in the game, as you can imagine. Can send you a photo the mechanic took if you think it’s helpful at all. And this was after a new wiring harness, control box, ignition panel etc [basically that turn-key kit you can get] which we did for other problems. Good luck!

[artdf175]

As Solarman suggested - check the IAC valve
which is a primary part that controls the air fuel mixture and idle speed
have a service manual? before you throw a bunch of money at parts it is always good to understand how they work- suggestion,

also in the sticky on errror codes if you push the ignition key in, once I think, it will cancel the error code until it is triggers again
Art