jamesmorioka
New member
Hi everyone,
I have a Honda 90hp DK4 outboard engine (February 2016) that has recently been acting up and setting off several alarms. This new outboard has just over 800 hours. After putting the boat in the water, I put the engines to the test, by running them hard, through drills which included running them at high RPMs at conducting lots of pivot turns. Immediately after running them hard, I turned off the engine, and let them cool down for a minute or so. After the minute passed, I would start the engine back up, and a "check engine alarm" would ring.
Using a diagnostic tool, I was able to tell that the alarm indicated a "IAC valve control failure 14-1". So, I began to troubleshoot.
We began with the shop manual, section 5-33 DTC 14-1 (IAC valve control failure), to check the electronics. We went through all necessary tests. Symptom reproduction test and IAC valve inspection test. We checked to make sure there was continuity between the ECM (engine control module) and the IAC valve, and there certainly was.
So, the next step was to inspect and replace the actual IAC valve. We first inspected it, by measuring the resistance between IAC valve #1 and #2 terminals of the 2-pin connector. The resistance was 13 ohms. Everything seemed to pan out, so must be the actual valve failing. We removed the IAC valve, inspected the gasket, everything seemed clean. We replaced it with a new IAC valve, and ran the engine in a large tub of water.
When running it in the tub of water, I could not duplicate the alarm. So, I thought I had fixed the problem. I thought, it would be smart to take it into the field and run it hard to see if the alarm would sound again, because it only happened when conducting those drills. I took the boat out, and sure enough, the check engine alarm sounded again. I brought the boat back in, hooked it up to the diagnostic tool, and it read the same, IAC valve control failure 14-1.
When taking the cowling off and running the engines, it makes this unique intermittent sound/vacuum sound (unlike our other 90 hp which has a consistent vacuum sound). The intermittent vacuum/sucking sound is coming from inside the air box or silencer, and sounds like the throttle plate inside the throttle body is opening and shutting, to adjust the amount of air flow going in. However, it does not affect the RPMs or create the engine to run rough. It is just a unique sound that I haven't heard before.
We swapped out ECM's thinking the computer had something to do with adjusting the air flow, but the new computer did not change the sound. I now think this is not a technical issue (impeller, thermostat, etc.) but rather an electrical issue greater than I can handle. I am beginning to have my doubts about the IAT sensor, or how the different sensors are affecting each other. Since the sound is intermittent, could it be an electronic short?
Please let me know if you have come across this problem before, or if you have any information that could be of help! Thank you very much for your time!
I have a Honda 90hp DK4 outboard engine (February 2016) that has recently been acting up and setting off several alarms. This new outboard has just over 800 hours. After putting the boat in the water, I put the engines to the test, by running them hard, through drills which included running them at high RPMs at conducting lots of pivot turns. Immediately after running them hard, I turned off the engine, and let them cool down for a minute or so. After the minute passed, I would start the engine back up, and a "check engine alarm" would ring.
Using a diagnostic tool, I was able to tell that the alarm indicated a "IAC valve control failure 14-1". So, I began to troubleshoot.
We began with the shop manual, section 5-33 DTC 14-1 (IAC valve control failure), to check the electronics. We went through all necessary tests. Symptom reproduction test and IAC valve inspection test. We checked to make sure there was continuity between the ECM (engine control module) and the IAC valve, and there certainly was.
So, the next step was to inspect and replace the actual IAC valve. We first inspected it, by measuring the resistance between IAC valve #1 and #2 terminals of the 2-pin connector. The resistance was 13 ohms. Everything seemed to pan out, so must be the actual valve failing. We removed the IAC valve, inspected the gasket, everything seemed clean. We replaced it with a new IAC valve, and ran the engine in a large tub of water.
When running it in the tub of water, I could not duplicate the alarm. So, I thought I had fixed the problem. I thought, it would be smart to take it into the field and run it hard to see if the alarm would sound again, because it only happened when conducting those drills. I took the boat out, and sure enough, the check engine alarm sounded again. I brought the boat back in, hooked it up to the diagnostic tool, and it read the same, IAC valve control failure 14-1.
When taking the cowling off and running the engines, it makes this unique intermittent sound/vacuum sound (unlike our other 90 hp which has a consistent vacuum sound). The intermittent vacuum/sucking sound is coming from inside the air box or silencer, and sounds like the throttle plate inside the throttle body is opening and shutting, to adjust the amount of air flow going in. However, it does not affect the RPMs or create the engine to run rough. It is just a unique sound that I haven't heard before.
We swapped out ECM's thinking the computer had something to do with adjusting the air flow, but the new computer did not change the sound. I now think this is not a technical issue (impeller, thermostat, etc.) but rather an electrical issue greater than I can handle. I am beginning to have my doubts about the IAT sensor, or how the different sensors are affecting each other. Since the sound is intermittent, could it be an electronic short?
Please let me know if you have come across this problem before, or if you have any information that could be of help! Thank you very much for your time!