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  1. #1
    apriliaforum expert deefred's Avatar
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    Cleaning of the stepper motor

    People have asked how to clean the stepper motor and below I have some pictures to show what it looks like disassembled.

    The stepper motor is attached to the lower RH side of the airbox.
    There are two hoses and one connector attached to it.
    Air comes from the airbox and is supplying filtered air to the stepper motor and the two hoses goes from the stepper motor to downstream of each throttle plate.

    The function of the stepper motor is to control idle when the throttle is in the closed position. It does this by varying the amount of air which is bypassing the throttle plate. The ECU is controlling the stepper motor to keep the idle to determined values depending of engine temperatures.
    When you turn the ignition ON a plunger inside the assy moves slightly up (i think) When the your turn the igntion OFF the plunger is moved all the way down to its endstop and then slightly up again. Its fighting against the endstop and makes some funny noises. This is an auto calibration routine.

    The stepper motor is attached to the airbox by two philips screws which are loctited. I suggest to remove the airbox for best possible access to the two screws to avoid damage.

    Once the stepper motor is removed you can seperate the motor part from the plastic housing.

    It is now very easy to clean the white plunger and the bore where the plunger moves up and down. You can see the two ports in the bottom of the bore.

    Check that the white plunger can only move slightly when you turn it with low force.

    If you want to also grease the gear inside the stepper motor it is a bit more complicated.
    Connect the electrical connector to the stepper motor which you hold in your hand. Turn ON and then OFF the ignition.
    The ECU will now drive the plunger to its end position but as it is removed from the plastic housing there is no end position any more so it will come flying as there is a spring pushing the plunger.
    Be prepared for this!
    Except for the spring there is also a thin sleeve.

    To install the plunger again (spring first then sleeve) screw it in until the recess in the thicker section matches the tab in the motor part.
    Now you will need to press the plunger hard like you want to press it in and at the same time turn the ignition ON then OFF. Your are now simulating the endstop and after 2 seconds about the plunger will be drawn in. You will need to repeat this two or three times to get it fully in.
    The picture with the plunger loose is nicked from Befbever.
    The spring and the sleeve is not shown.
    Attached Images Attached Images     
    Last edited by deefred; 09-06-2008 at 12:26 AM.
    2001 RST Futura in stream Silver.
    Mods: Modified Öhlins fork from mille R, EBC 320mm brake discs, HEL front brakelines, Carbon RS 250 front fender, Wiring mod for charging. Engine related:05 map, Iridium plugs, tuneboy, derestriced intake, old mille airboot, staintunes exhaust. Lambda bung hardbrazed in the "breadbox". Öhlins mille R rear shock with 110N/mm spring and the integrated hydraulic preload adjuster. LED Voltmeter installed inside the dash for monitoring charging. Duc 999 radial m/c for brake and clutch.
    NWS hugger. Equipment: Famsa tankbag,
    CBR 600 -07 MOSFET R&R FH008EE providing stable 14.4 - 14.5 V (with my wiring mod). Daytona heated grips with mccoi pwm controller and automatic chain oiler

  2. #2
    apriliaforum expert RAS's Avatar
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    So what looks like a threaded rod is really more a circular "rack" and the motor spins a pinion? Nice write-up. Takes all the mystery away from this thing. thanks.

  3. #3
    apriliaforum expert deefred's Avatar
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    Yes, thats correct.

    I edit the text in the beginning as It was totally wrong about the two hoses.
    2001 RST Futura in stream Silver.
    Mods: Modified Öhlins fork from mille R, EBC 320mm brake discs, HEL front brakelines, Carbon RS 250 front fender, Wiring mod for charging. Engine related:05 map, Iridium plugs, tuneboy, derestriced intake, old mille airboot, staintunes exhaust. Lambda bung hardbrazed in the "breadbox". Öhlins mille R rear shock with 110N/mm spring and the integrated hydraulic preload adjuster. LED Voltmeter installed inside the dash for monitoring charging. Duc 999 radial m/c for brake and clutch.
    NWS hugger. Equipment: Famsa tankbag,
    CBR 600 -07 MOSFET R&R FH008EE providing stable 14.4 - 14.5 V (with my wiring mod). Daytona heated grips with mccoi pwm controller and automatic chain oiler

  4. #4
    apriliaforum expert Befbever's Avatar
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    The function of the stepper motor is to control idle when the throttle is in the closed position.
    ...and at all ambient temperatures, right? I'm just saying this because we have no seperate "choke" like the Nippondenso FI systems do.

    Rack and pinion is exactly right.
    Nice write-up, Frederick.
    This Must Be The Place
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  5. #5
    apriliaforum expert deefred's Avatar
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    Quote Originally Posted by Befbever View Post
    ...and at all ambient temperatures, right? I'm just saying this because we have no seperate "choke" like the Nippondenso FI systems do.

    Rack and pinion is exactly right.
    Nice write-up, Frederick.
    I think it is only checking for engine temp actually.
    In tuneboy thats the only parameter for idle speed at least.
    74 degrees Celsius engine temp and higher, the idle speed is maintained at 1280rpm.
    2001 RST Futura in stream Silver.
    Mods: Modified Öhlins fork from mille R, EBC 320mm brake discs, HEL front brakelines, Carbon RS 250 front fender, Wiring mod for charging. Engine related:05 map, Iridium plugs, tuneboy, derestriced intake, old mille airboot, staintunes exhaust. Lambda bung hardbrazed in the "breadbox". Öhlins mille R rear shock with 110N/mm spring and the integrated hydraulic preload adjuster. LED Voltmeter installed inside the dash for monitoring charging. Duc 999 radial m/c for brake and clutch.
    NWS hugger. Equipment: Famsa tankbag,
    CBR 600 -07 MOSFET R&R FH008EE providing stable 14.4 - 14.5 V (with my wiring mod). Daytona heated grips with mccoi pwm controller and automatic chain oiler

  6. #6
    apriliaforum Member Smok3's Avatar
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    Please tell me if you had problems since you cleaned the stepper motor

    Thanks for advice,but it seems i`m have not solved anything
    when I cleaned,I think to replace... though I measured and it is good....
    -2001 RST Futura wearing Black.
    -Devil Magnum Exhaust ,Metal fuel line disconnect,Wiring mod done and waterproof conectors Reg/Rec Mod,Hepco-becker,Aftermarket Sliders,Onboard voltmeter,K&N inside but with the stok air box,HID = 1 X 35 W Low,2 x 55 W High,Saito heated grips,12 V Socket, SOLD @ 73 k KM and 11 k Mile
    - buy Honda VFR800 Vtec,Full Givi,touring windshield.....and that's all for now

  7. #7
    apriliaforum expert RobC's Avatar
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    Thanks Deefred, time to check mine as it's not making any 'funny noises' on start/stop.

  8. #8
    apriliaforum expert The Fixer's Avatar
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    Thumbs up

    Good info for the archives...thanks!
    “The road’s what counts...don’t worry about where it’s goin’."
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  9. #9
    apriliaforum expert bobdavis73's Avatar
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    Awesome post Thanks!!!!

    Bob


    "Although all men are born free, slavery has been the general lot of the human race. Ignorant - they have been cheated; asleep - they have been surprised; divided - the yoke has been forced upon them. But what is the lesson? ...the people ought to be enlightened, to be awakened, to be united, that after establishing a govenment they should watch over it.... It is universally admitted that a well-instructed people alone can be permanently free."
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  10. #10
    apriliaforum expert deefred's Avatar
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    Does it always idle high at all temperatures?
    Did this problem come suddenly?

    Have you checked your CO levels?

    Can be a lot of things, temp sensors, TPS not at zero with throttle shut etc.
    2001 RST Futura in stream Silver.
    Mods: Modified Öhlins fork from mille R, EBC 320mm brake discs, HEL front brakelines, Carbon RS 250 front fender, Wiring mod for charging. Engine related:05 map, Iridium plugs, tuneboy, derestriced intake, old mille airboot, staintunes exhaust. Lambda bung hardbrazed in the "breadbox". Öhlins mille R rear shock with 110N/mm spring and the integrated hydraulic preload adjuster. LED Voltmeter installed inside the dash for monitoring charging. Duc 999 radial m/c for brake and clutch.
    NWS hugger. Equipment: Famsa tankbag,
    CBR 600 -07 MOSFET R&R FH008EE providing stable 14.4 - 14.5 V (with my wiring mod). Daytona heated grips with mccoi pwm controller and automatic chain oiler

  11. #11
    apriliaforum Member Smok3's Avatar
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    Quote Originally Posted by deefred View Post
    Does it always idle high at all temperatures?
    Did this problem come suddenly?

    Have you checked your CO levels?

    Can be a lot of things, temp sensors, TPS not at zero with throttle shut etc.


    The only things that do not know how to do is to adjust TPS at zero,
    the rest I can handle to check thanks againfor advice.
    Can you help me with some advice on TPS ?
    -2001 RST Futura wearing Black.
    -Devil Magnum Exhaust ,Metal fuel line disconnect,Wiring mod done and waterproof conectors Reg/Rec Mod,Hepco-becker,Aftermarket Sliders,Onboard voltmeter,K&N inside but with the stok air box,HID = 1 X 35 W Low,2 x 55 W High,Saito heated grips,12 V Socket, SOLD @ 73 k KM and 11 k Mile
    - buy Honda VFR800 Vtec,Full Givi,touring windshield.....and that's all for now

  12. #12
    apriliaforum expert deefred's Avatar
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    Sorry,
    For the TPS to be set to zero you need to go to a workshop with the Axone tool or if you know someone who has the tuneboy cable.

    It can not be done otherwise.
    2001 RST Futura in stream Silver.
    Mods: Modified Öhlins fork from mille R, EBC 320mm brake discs, HEL front brakelines, Carbon RS 250 front fender, Wiring mod for charging. Engine related:05 map, Iridium plugs, tuneboy, derestriced intake, old mille airboot, staintunes exhaust. Lambda bung hardbrazed in the "breadbox". Öhlins mille R rear shock with 110N/mm spring and the integrated hydraulic preload adjuster. LED Voltmeter installed inside the dash for monitoring charging. Duc 999 radial m/c for brake and clutch.
    NWS hugger. Equipment: Famsa tankbag,
    CBR 600 -07 MOSFET R&R FH008EE providing stable 14.4 - 14.5 V (with my wiring mod). Daytona heated grips with mccoi pwm controller and automatic chain oiler

  13. #13
    apriliaforum Member Smok3's Avatar
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    Quote Originally Posted by deefred View Post
    Sorry,
    For the TPS to be set to zero you need to go to a workshop with the Axone tool or if you know someone who has the tuneboy cable.

    It can not be done otherwise.
    Grrrrr service again
    are not good mechanic in Romania from Aprilia
    ...in service do not know guys from Aprilia the oil to change by the book last time had 4L of oil in engine,not all related to the air box,and I came home with 2 screws and lost on the way.
    That prefer to do my own thing to the engine and ask the forum here.


    Thanks again I see it as a follow up to solve
    -2001 RST Futura wearing Black.
    -Devil Magnum Exhaust ,Metal fuel line disconnect,Wiring mod done and waterproof conectors Reg/Rec Mod,Hepco-becker,Aftermarket Sliders,Onboard voltmeter,K&N inside but with the stok air box,HID = 1 X 35 W Low,2 x 55 W High,Saito heated grips,12 V Socket, SOLD @ 73 k KM and 11 k Mile
    - buy Honda VFR800 Vtec,Full Givi,touring windshield.....and that's all for now

  14. #14
    %@*#&! hank's Avatar
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    Now a sticky in the 1000cc FAQ section

  15. #15
    apriliaforum expert Motech's Avatar
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    Idle Air Control Valves (IAC) are often referred to as "stepper" motors due to the scope patterns they produce when activated. The patterns resemble the side view of a stairway. As Deefred's pictures show, they incorporate a plunger attached to a worm gear, which is moved in and out of a bore via DC motors and a rotary gear.

    Cleaning the IAC--any IAC--is usually a final attempt to salvage a malfunctioning unit. Sometimes it works, but it's always temporary; most time it does not. If the plunger and bore have become dirty enough to jam up and prevent the motor from smoothly moving the plunger in and out of the bore, the motor is usually compromised and needs to be replaced.

    Most IAC cleaning is futile, but since our bikes utilize a separate bore housing that allows total exposure of the plunger, it is not as tricky to service as most other types, and less likely to suffer additional damage from cleaning. This should be considered maintenance. If an IAC truly is binding, or not opening and closing as designed, additional troubleshooting is highly recommended.

    Commanding the IAC to close until the worm gear, plunger and spring are ejected is not a wise idea. As Deefred noted, it could easily result in loss of critical parts. It is also very easy to damage fragile threads of the worm or rotary gears upon reassembly, and these Aprilia IAC units are not so cheap. Cleaning inside the rotary gear/motor area is not a good idea either as solvents can seep into and damage weakened motor/circuits. A shot of WD40 won't hurt, but that's about all I would be comfortable with.

    Our Aprilias are built with GM style IAC valves that utilize a very common electrical connector that is found on Ducati, Moto Guzzi, Triumph, Harley Davidson, Buell, etc... and many automotive applications like Isuzu, GM, Saturn, Chrysler, Jeep, Saab and others. Therefore, there are remote testers available to fit this IAC that some skilled automotive diagnosticians will have in their toolboxes. This tester bypasses the ECU and plugs directly into the IAC, which then can be opened and closed using a hand-held controller, raising and lowering the idle speed at will. If you ever doubt your IAC integrity, seek out someone who has this tester. It takes a LOT of guesswork out of IAC diagnostics, and it has the added benefit of allowing you to custom taylor your idle speed at a fixed rate during tuning for more precise throttle body synchronization.

    BTW, I have never met a motorbike technician who has this tool, and those who have seen me use mine get pretty excited.

    IAC cleaning can be misleading. If you do it and still have your symptom, does that mean the IAC is bad? Or is the computer sending a wrong signal? If so, why? What inputs are fooling the computer? Or is there an open or shorted circuit somewhere between IAC and ECU, battery or ground? Did my cleaning wreck my IAC? (happens a lot) What's really going on here?

    I guess I'm not comfortable with DeeFred's recommendation to tamper with a component that was not malfunctioning. I believe in the adage that you don't fix what ain't broke. But hey, as long as it's your bike, and not a friend's or customer's... Or mine!

    But if there's a definite idle control problem with the valve, and if the bore and plunger are binding, cleaning can sometimes improve IAC performance. Guesswork sucks though. It's always better to know what's really going on.

    Motech

    EDIT:

    One last thing

    The most definitive diagnosis of a failing IAC valve is also the most unsophisticated. If you have an irregular idling problem, like stuck high or surging, access and rap on your IAC valve during the idling symptom with something like the handle of a screwdriver. Rap sharply a few times, but not hard enough to damage it. If your idle controls are restored, or the symptom changes a little when you strike it, it's your IAC or the connections.
    Last edited by Motech; 03-05-2010 at 02:53 PM.
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