DF 50 MAP sensor issue

[kapelhanoj]

So I just bought a used 2002 Johnson/Suzuki 50 with a bad ECU... found a used ECU for a reasonable price & plugged it in.
Motor now starts, but won't idle and is showing a 3-2 code (MAP sensor). I pulled the sensor, the hose & filter are open & the sensor is reacting to vacuum. The bad idle/hard starting symptoms fit with the trouble shooting chart in my manual for code 3-2.

I did not have a manometer on hand during my test to get a full range of voltages, but at 0" vacuum I'm getting 4.5v instead of 4.0v listed in my manual.

Does anyone know if .5v out of spec is enough to cause the bad idling? The manual does not state a tolerance, just "about" 4.0v etc...

I was doing some reading on here & other sites & found a lot of people reporting problems with corrosion causing exhaust leakage and an associated 3-2 code, but only found reference to this on 90+ hp. Does anyone know if that issue has cropped up on the 50hp as well?

Thanks!

Jonah

[Rederik]

Sensor Errors

Hi

I have a DF50 with some problems, where do you find the "error" codes? my "check engine" lamp lights up twice when the "controll" procedure is over. what does that mean?

My problem with the engine is that when I sail with more than 2500 RPM, suttenly it dies.. If I take turn off the gas panel, some times it does not die entirely, but just goes up and down in RPM's and ends up with about 800-1000 RPM, then I can sail again if its under 2500 RPM there is no problems.

Any Ideas?

Regards
Michael

[catacom225]

Map

Try removing the IAC valve clean and test , Check idle speed is correct

[JPN_80]

MAP sensor?

Greetings from Finland!
I have met similar problems now with DF50 yearmodel 2002, except it has given 3-2 fault code only once, now still effecting so that won't accelerate cold more than 3000RPM and after heated up is sometimes working til 6000RPM and sometimes not. During cold, motor is shaking a much and feels like one cylinder is out. At lower RPM's sometimes running OK and sometimes not.

What is the IAC valve? Where is it located and how to clean it?

I'm out of Owner's manual, does anyone have one in PDF?
Thanks!

[tugboat]

I know it's a year on but I would Say the first thing Rederik Should do is change the fuel filter, as for the other problem I too have got the Johnson suzuki df50 had it 6 years no problems, but this year the check engine light started to come on when on tick over and the alarm goes for 30secs no numbers flashing. Now it comes on engine stops, 32 flashes. No other problems start up and runs full throttle have checked idle switch, idle control valve, map sensor and pipe, plugs are perfect as you would expect on a good engine, have tried adjusting tick over but it runs ticks over fine on land with water on or in a tank it only seems to happen after a run at full throttle, it goes through the slowing down stages then when it gets to about 900-850 it misses a bit alarm goes, map pipe, then stops if the throttle is not opened. If left at 1000 or above no problems Any suggestions Please
Tug

[redlowrey]

So I just bought a used 2002 Johnson/Suzuki 50 with a bad ECU... found a used ECU for a reasonable price & plugged it in.
Motor now starts, but won't idle and is showing a 3-2 code (MAP sensor). I pulled the sensor, the hose & filter are open & the sensor is reacting to vacuum. The bad idle/hard starting symptoms fit with the trouble shooting chart in my manual for code 3-2.

I did not have a manometer on hand during my test to get a full range of voltages, but at 0" vacuum I'm getting 4.5v instead of 4.0v listed in my manual.

Does anyone know if .5v out of spec is enough to cause the bad idling? The manual does not state a tolerance, just "about" 4.0v etc...

I was doing some reading on here & other sites & found a lot of people reporting problems with corrosion causing exhaust leakage and an associated 3-2 code, but only found reference to this on 90+ hp. Does anyone know if that issue has cropped up on the 50hp as well?

Thanks!

Jonah

A good running engine at idle will have about 1.5 volts at idle and around 4.5 volts at wide open throttle. To check it properly you need a vacum pump and a digital multimeter, remember this any problem whether it is fuel or mechanical will effect map sensor voltage,so check it properly or you will be a couple of hundred bucks out of pocket.

[tugboat]

Hi. Redlowrey Thanks for your help, have checked it with vacuum pump and the voltages are good. Tried a vacuum gauge on the pipe but the results looked ok, as I said earlier it seems to be good on the wash with water on just seems to do it at sea, have tried to read it at sea but found it a problem, next step after speeding up the tick over I may add some wires on the map and put my scope on the engine at sea not easy but think i can do it, it's not too much of a problem as it runs fine at 1000 rpm or above plugs are good so mixture looks ok. Forgot to say I have tried running back fast but by the time I get it on the wash it's ok.
Thank again any advice welcome.
T

[redlowrey]

Your problem sounds more like a closed throttle switch problem,or you have not set the air bypass srew adjustment right. if the closed throttle switch plays up, on sudden decelaration the iac won't work properly and you won't get that dash pot effect and the engine will stall. I don't think you have a map sensor problem and If you have not set the air bypass screw right the IAC won't work properly. Take the iac valve off and make sure the port is not blocked and clean the throttle plate both sides with some carbi cleaner. You say if you keep the throttle at 1000 rpm it is all right, on decelaration when the ecm see's the closed throttle switch signal the ecm sends a signal to the iac to bypass more air to keep the idle up and it the timing stays a little more advanced

[tugboat]

Thanks again for advice I have the IAC value off at the moment it's clean and seems to work ok on a 5v power supply, switches fine, I did originally suspect the close throttle switch but again it tests ok with a meter, not tried the air by pass screw yet hope it is blocked, but the engine/boat are laid up for the winter but I will let you know April next year.
Thanks again T

[tugboat]

Well it took loads of time, the fault is an exhaust leak that fills the cowl with gas on tickover starving the engine of air, when the boat moves forwards fast it seems to clear, but big job requires a full strip down and could be the end of the road for the castings or engine the whole side is thin.