Throttle motor control issues

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Throttle motor control issues

Ashley
I'm having some issues with my EF2800i throttle control.  WOT is all that the genny seems to do.  The AC output is all good there is no problem there.  Eco button seems to  do nothing at all.  I have removed the throttle motor and left it wired up and observed that upon starting the engine it rotates 90deg (opening the throttle direction) every time.  I have never seen it go in the other direction (closing the throttle).  The engine runs fine with manual throttle control.  The throttle motor does not move again with any adjustment of throttle, revs or load.  I have manually driven the stepper motor with suitable circuitry to confirm it works correctly in both directions.  The EF2800i ECU can drive the stepper proving the stepper power circuit is working fine but the logic seems to be incorrect.  It seems to me that the ECU doesn't know the RPM of the engine and tries to increase it by opening the throttle.  All wiring and connections are in good condition and resistance values of the various components check out fine.  Has anyone had similar problems or got any answers.
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Re: Throttle motor control issues

Grumps
I am looking at the service manual for my ef2400is. This is how they say to test the stepper motor. Looking at the motor from the top the pins are 1-5 from right to left. Set your meter on the 1 ohm scale measure between 3-1, 3-2, 3-4, and 3-5 . Coil resistance 250 ohm +_ 20% at 68 deg F. If out of spec replace stepper motor. Also a bad or incorrect spark plug can mess with the electronics. Hope this helps .
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Re: Throttle motor control issues

Ashley
Hi Grumps
I've connected the stepper motor up to a 12V driver circuit with a pulse order of 1 2 5 4 ... for forward and  4 5 2 1... for reverse and pin 3 as common.  This drove the stepper in both directions perfectly.  I have also checked the impedance of the pins and they are correct at 250 ohms.  The ECU is able to move the motor but only to open the throttle, not sure if ECU knows what the engine is doing?.  How does the ECU detect engine RPM?.  I'm guessing through the AC input frequency of the stator?.  I'll buy and install a new spark plug and report my findings.  Thanks for your feedback.    
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Re: Throttle motor control issues

Grumps
This may be a long shot , check the Econ switch and see if it actually is making and breaking contact also the connections for the switch.
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Re: Throttle motor control issues

Ashley
This post was updated on .
Thanks again Grumps, I have checked the switch assembly and wiring and I checks out fine.  Not sure what impedance readings should be on wires entering control box but have open circuit.
I have ordered a new OEM complete carb assembly and some other bits.  They are due to arrive in a few weeks and I will report back then with my findings.  
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Re: Throttle motor control issues

Ashley
I've installed the new OEM carb assy with new throttle motor and new spark plug.  Once again, WOT and the engine bounces off the rev limiter.  I manually close throttle then start the engine and the ECU will fully open the throttle but will not govern it.  I'm thinking the ECU is not detecting the engine speed and tries to increase the revs by opening the throttle.  Looks as through a new ECU or some sort of work around with an Arduino.  New ECU is out of the question, to expensive and since the AC side is OK, so and Arduino with an AC current sensor, optical isolator (hooked up to the trigger circuit), a stepper motor drive  circuit and some experimenting to get the right control system.  Should be fun?.  It all should fit nicely inside the control panel.  Approx cost is around $40 and some labor of love.      
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Re: Throttle motor control issues

Grumps
Thanks for the update, this will be interesting to follow. Sounds like you are very knowledgeable with electronics.
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Re: Throttle motor control issues

Ashley
I find electronic circuits very hard to diagnose  and fix when they are encased in resin.    
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Re: Throttle motor control issues

Madmac
In reply to this post by Ashley
Ashley, My EF2400I has the same problem and I have checked out the stepping motor same as you and it works fine. If you take the front panel with all the instruments in it off and look up under the top panel there is a circuit board which controls the stepping motor. I purchased a new one of these and it still did not fix my issue, but yours may be a problem. Had a electronics man check out the ECU unit and he confirmed that it has a problem.
My ECU has now gone to the stage of not allowing the 240v circuit to output power so as a new one cost around A$1600 I may as well scrap it.
That's about all I can tell you.
Regards
Madmac
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Re: Throttle motor control issues

Ashley
Thanks Madmac,
My model is the EF2800i and there is a small board inside the panel but the manual says that it called the 'Oil Warning Unit'.  It looks like on my gen the throttle control unit is embedded inside the main ECU making it unserviceable.  I now have a achieved a governed engine which can be set by a potentiometer but I have not received  the current sensor to complete the system.   Setting the PID controller was a challenge but will need to be adjusted once the new algorithm is used in conjunction with the current sensor.  
Thanks again for you input Madmac.
 
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Re: Throttle motor control issues

CycleRob
This post was updated on .
Ashley,
 The correct factory setting for the throttle motor control unit is with the throttle shaft plate turned all-the-way against the full throttle stop when the engine is off. Yes, that setting does not make sense unless you consider where almost every small engine's carburetor is at when started . . . .  at  FULL THROTTLE.
Try again!
Talent, On Loan, From God  --Rush Limbaugh--
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Re: Throttle motor control issues

Ashley
Hi CycleRob,
The manual says that the throttle should be in the wide open position, this for starting purposes but it really doesn't matter because the stepper motor will move according to the engine revs, it dosen't care what position it is in, it only knows the RPM and how to govern them when running.  The choke will operate better with WOT.  You can manually close the butterfly and start the engine and you will notice no difference in operation, other then it may be more difficult to start.  The stepper doesn't have any limit switches or need any.  It can be driven into the end of travel or manually moved with no damage or problems.
Regards  
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Re: Throttle motor control issues

CycleRob
Ashley,
 That is true about stepper motor performance -but- the speed control electronics needs to know the throttle butterfly is at the calibrated starting point when you pull the recoil starter.
Have you tried it at full throttle yet ??
Talent, On Loan, From God  --Rush Limbaugh--
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Re: Throttle motor control issues

Ashley
My final update on my EF2800i inverter generator project.  As in previous entries I found out that the ECU has some issues in controlling the throttle motor.  The ECU being fully encased in resin makes the entire ECU unserviceable and replacing it was not an option because of the price.  The AC side of the ECU is fully functional.   I embarked on a mission to make my own ECO/throttle control unit.   The final system uses two 8 bit 16mhz microcontrollers, a potentiometer, a current sensor and an opto isolator for the ignition sensor.  A PID algorithm with the Amperage values added, are computed to output the required pulses to the throttle stepper motor.   Having underestimated the task, causing many hours of rev limiter bouncing, I have finally a stable working system.  There are a few tricks needed when using a stepper motor instead of a servo motor in combination with the PID.  In the end it all fits neatly inside the front control box and a total cost of about $40.  Probably spent about 40 hours or more making it though.  It was worth the effort.  
 
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Re: Throttle motor control issues

Madmac
Ashley, Thank you for your update and great to see you have rectified your issue.
I have fixed mine by fitting a three position manual throttle which works for me.


Sent from my iPad

On 18 Nov 2015, at 8:04 PM, Ashley [via Yamaha Generator Fan Club] <[hidden email]> wrote:

My final update on my EF2800i inverter generator project.  As in previous entries I found out that the ECU has some issues in controlling the throttle motor.  The ECU being fully encased in resin makes the entire ECU unserviceable and replacing it was not an option because of the price.  The AC side of the ECU is fully functional.   I embarked on a mission to make my own ECO/throttle control unit.   The final system uses two 8 bit 16mhz microcontrollers, a potentiometer, a current sensor and an opto isolator for the ignition sensor.  A PID algorithm with the Amperage values added, are computed to output the required pulses to the throttle stepper motor.   Having underestimated the task, causing many hours of rev limiter bouncing, I have finally a stable working system.  There are a few tricks needed when using a stepper motor instead of a servo motor in combination with the PID.  In the end it all fits neatly inside the front control box and a total cost of about $40.  Probably spent about 40 hours or more making it though.  It was worth the effort.  
 


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