Hello, just joined and first post as I am troubleshooting a frustrating idle issue. Thank you for any help or ideas you can offer!
I have two 2010 DF90As and earlier in the fall the stbd motor started to develop a low, rough sounding idle, but the tach would still read the normal 500-600RPMs. Over the course of a few trips I would get bubbling from the thru-prop exhaust and small oily bubbles coming thru as well. As soon as I would come up over 1000RPMs the motor would run great all day, but when the throttle was brought back to neutral the same low bubbly idle would return. Just a couple times the motor would not start cold, but when I removed the cowling, it would start right up. After four or five runs like this, the idle continued to get worse and the motor would stall once brought back to idle. Throughout this time the motor did not throw any codes.
I started looking into the simple things like a mud dauber nest clogging the above water exhaust...I live in the tropics and some neighboring boats have had this problem...but all clear. Next, the symptoms pointed to the IAC valve; I removed it and the plunger seemed to operate fine when the key was turned. It was not dirty, but I sprayed it with some throttle body cleaner as well.
On the next test, the idle increased to 1000RPMs with a good bit more oily bubbles and the motor then threw the 2-3 (IAT Sensor) code. I thought I had finally found the culprit so I replaced the IAT Sensor and ensured the wires and connection looked good.
On the next test the 2-3 code is gone, but its been replaced with a 2-2 (Air Intake System) code and the idle "smoothed" with no oily bubbles...but its running 1500RPMs in neutral and has a loud air sucking sound. If I increase the idle it runs up, but will not return below 2000RPM. I thought maybe a throttle cable issue, but it does the same if I disconnect the cable and increase the RPMs manually at the throttle body.
So now I am trying to figure out where to go next...I have the manual for the motors and for the 2-2 code and it says to check the voltage on the throttle position sensor and for air leaks at the MAP sensor, IAC and intake manifold. I checked all the sensor connections and they looked good, but haven't checked the TPS voltage yet.
I think my next check after the TPS voltage will be to swap the IAC valve from the port motor which idles great and see if that makes a difference (I should have done this back when I had the stbd one removed).
But, with the numerous sensor and parts that the 2-2 code points to, I'm looking for ideas on the next step? And any ideas on something to check that I am missing...no matter how simple!
Thank you again for the help. I am overseas in a remote area and am trying to troubleshoot this issue myself...
I have two 2010 DF90As and earlier in the fall the stbd motor started to develop a low, rough sounding idle, but the tach would still read the normal 500-600RPMs. Over the course of a few trips I would get bubbling from the thru-prop exhaust and small oily bubbles coming thru as well. As soon as I would come up over 1000RPMs the motor would run great all day, but when the throttle was brought back to neutral the same low bubbly idle would return. Just a couple times the motor would not start cold, but when I removed the cowling, it would start right up. After four or five runs like this, the idle continued to get worse and the motor would stall once brought back to idle. Throughout this time the motor did not throw any codes.
I started looking into the simple things like a mud dauber nest clogging the above water exhaust...I live in the tropics and some neighboring boats have had this problem...but all clear. Next, the symptoms pointed to the IAC valve; I removed it and the plunger seemed to operate fine when the key was turned. It was not dirty, but I sprayed it with some throttle body cleaner as well.
On the next test, the idle increased to 1000RPMs with a good bit more oily bubbles and the motor then threw the 2-3 (IAT Sensor) code. I thought I had finally found the culprit so I replaced the IAT Sensor and ensured the wires and connection looked good.
On the next test the 2-3 code is gone, but its been replaced with a 2-2 (Air Intake System) code and the idle "smoothed" with no oily bubbles...but its running 1500RPMs in neutral and has a loud air sucking sound. If I increase the idle it runs up, but will not return below 2000RPM. I thought maybe a throttle cable issue, but it does the same if I disconnect the cable and increase the RPMs manually at the throttle body.
So now I am trying to figure out where to go next...I have the manual for the motors and for the 2-2 code and it says to check the voltage on the throttle position sensor and for air leaks at the MAP sensor, IAC and intake manifold. I checked all the sensor connections and they looked good, but haven't checked the TPS voltage yet.
I think my next check after the TPS voltage will be to swap the IAC valve from the port motor which idles great and see if that makes a difference (I should have done this back when I had the stbd one removed).
But, with the numerous sensor and parts that the 2-2 code points to, I'm looking for ideas on the next step? And any ideas on something to check that I am missing...no matter how simple!
Thank you again for the help. I am overseas in a remote area and am trying to troubleshoot this issue myself...
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