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Advanced engine electronics operating as


The industry’s leading computer module repair
facility for outboard motors since 2001.
Symptoms & Solutions

Oil consumption seems excessive with my motor. Is the ECU/EMM defective?

An ECU/EMM failure can not cause excessive oil consumption. The most likely causes of excessive oil use are - Oil lift pump failure, restriction (pinching) of the oil return line, oil injector failure.

Your usage cycle could also be a contributing factor. When the engine coolant temperature is below normal temperature, as the engine is accelerated above 2500 RPM, the oiling system delivers multiple injection shots. If this operational cycle is continually repeated, excessive oiling could be observed.

My motor experienced detonation damage to a cylinder. Is the ECU/EMM defective?

The air cooled ECU does not contain an ignition system. It is a separate module. If anything, suspect the ignition module. Water-cooled ECUs and EMMs have the ignition system incorporated into them. It is extremely rare to experience an ignition system failure which will cause detonation damage.

It is quite simple to test the ignition system if you suspect it caused cylinder damage. Attach a timing light to the high tension lead of the damaged cylinder. Perform a static ignition test on all cylinders except the damaged one. Watch the timing light carefully as you check each cylinder. If the light flashes, there is a failure of the ignition system which is causing cross-firing and it must be repaired or replaced. If the timing light does not flash, the ECU/EMM is most likely not the cause of cylinder damage.

My motor seems to run rough at certain RPM ranges, particularly off-idle through 2500 RPM. I would like to have my ECU repaired. What should I do?

Before sending your ECU/EMM in for test and/or repair, particularly when your troubleshooting has not pinpointed a specific failure, we suggest that you give our technical staff a call. We will be pleased to assist in making specific tests/measurements which will provide a higher degree of certainty that the ECU/EMM is truly defective. If you send your ECU/EMM for testing and no defects are found, you will be charged our standard test price.

While performing a cylinder drop test, I noticed one or more cylinders did not respond properly. I believe the ECU/EMM is defective because the cylinder has great compression, spark, etc.

When performing a cylinder drop test, always increase the throttle to 2.5 % (25 counts) or higher. This throttle setting causes the idle governor software to disengage. When active, the idle governor can often mask symptoms and effects.

My motor idles too slowly. I think the idle governor is broken.

The idle governor is a software program which changes various operating parameters in response to changes in the motor. It can not break! A problem like this is always traced to another component/setup failure, such as a low flowing injector, improper ignition offset timing, blocked exhaust pressure port, etc. The idle governor software can only make so much correction, after that the engine speed will change from the desired idle speed. Motors with a lot of operating hours - suspect a low flowing fuel injector.

My ECU/EMM communicates with my laptop for about 10 seconds or so and then goes dead. What is wrong?

Most likely, nothing is wrong with your controller. It is probably entering the diagnostic readout mode because there is a defect in the throttle position sensor or an intermittent connection in the ground or wiper (green) connection to the throttle position sensor. When the ECU/EMM senses a wide open throttle (or near WOT) condition at power-on, it assumes you are attempting to use the auxiliary (Check Engine Light) diagnostic mode. Verify this condition by watching the Check Engine Light, which should start flashing after the fuel pump shuts off.

My ECU/EMM has been overheated and now the engine runs poorly. What has happened?

If your water cooled ECU/EMM has overheated, there are several possible failure modes. The most likely is damage to the switching regulator circuitry of your EMM. This generally results in a code #17 or #27 (battery or alternator voltage) error.

While this can be repaired, it is extremely important that you determine the cause of overheating. In all cases, the overheating of the EMM is due to low or blocked water flow through the EMM. Water flow should be checked both upstream and downstream of the EMM. If the water flow is not corrected, your replacement EMM will most likely fail too.

Be particularly cautious when the EMM maximum temperature is higher than the engine maximum temperature. This will never normally occur. Typical EMM temperatures don't exceed 70-80°C. Look for pinched coolant lines, misrouted hoses, and blockage within the vapor separator.

The repaired/replacement EMM doesn't function correctly. The symptoms are - the motor starts and dies, drops a cylinder when I accelerate, or idles poorly.

Before you blame the EMM, verify the engine timing first. Next, verify the fuel injector serial numbers and coefficients. We have recently seen failures which are the result of incorrect fuel injector coefficients entered in the EMM. Usually, one digit of the coefficient is missing. This will result in too little or too much fuel being injected into the cylinder with subsequent performance problems.

DFI Technologies, Inc. cannot provide coefficient information unless we have repaired your particular fuel injector. Coefficients for other injectors must be obtained from the manufacturer.

My engine is running a little rough. It seems lean on a cylinder. My friend told me he heard the fuel injector driver could be getting weak and I should have the EMM repaired.

We aren't sure where this urban myth originated. The injector driver is an electronic switch which controls the flow of current through the injector. This device either works or it doesn't. There is no such thing as getting weak or tired!

When the injector driver fails - 99.9% of the time it fails in a shorted condition. This is easily verified by finding the extremely hot injector and/or blown fuse.

If the motor really is lean on a cylinder, there are a couple of other areas you should explore. First, the injector could be losing performance and in need of a rebuild. Second, please verify those injector coefficients. Finally, if the symptoms show up while the motor is running under homogeneous conditions, look for an air leak which is making it lean.

I have a newer motor with an EMM. It keeps setting codes 38 and/or 39 (oiling system failures). I replaced the EMM and still have the same problem. I know the motor is getting oil. What's wrong?


I just don't understand ECU offset. What is going on?


Sometimes my motor revs up all by itself. I’ve done all the checks. I suspect my ECU/EMM is bad.

Unlikely, most “runaway” situations have turned out to be a fuel leak. Ficht motors have enlarged holes in the throttle plates to support stratified running. Any extra fuel causes the engine to run homogeneous, thus the “runaway”. Some typical culprits of fuel leaks are the fuel lift pump, the vapor separator vent line, and even the oil lift pump. It is also possible to have a leaky injector. Check them all for signs of fuel/oil. If they are all clear, go to the engine diagnostic screen in your diagnostic program. Watch your fuel pulse width, in general, if it decreases the ECU/EMM is fine.

I keep getting TPS codes (12, 13, or 14). Where do I send my ECU/EMM?

Don’t send it just yet. We have NEVER seen an ECU/EMM cause a TPS failure. Check your TPS for smooth operation both with an ohmmeter then suspect the connector (wiring harness side). Dig into it and look for bad crimps or broken pins. The connector is the usual suspect.

Almost every time I go out, the codes for the air temp sensor malfunction are set. Is my ECU/EMM bad?

It’s possible, but here at DFI we have changed our wiring harness twice and repaired it several times. The issue has always been the air temp. sensor wire being broken. Maybe it is just a coincidence but give the harness a thorough test.