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Discussion Starter #1
does anyone knows what the stepper does,, it`s the device that connect in the air box,, then goes 3 tube to each air entrance to the cyliinders, near the injectors.

can that affects the bike regarding the fuel ratio,, bike running rich
 

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What is described as the "stepper" is the (idle air control valve) it is a stepper motor ( that is a motor that moves in set increments, by recieving inputs from the electronic control module) The motor moves a rod in and out to open and shut the airflow from the airbox to the throttle bodies below the butterfly valves. The ecm is set to idle at say 1200rpm and it uses inputs from several sensors and then regulates the stepper and fuel injection and ignition.
The stepper could fail and cause rich and poor running. if you look in the airbox with the top removed the stepper can be seen on right side. if the engine is run the stepper can be seen to move if reved up and down. you can see a white plunger that uncovers the little ports to the outlet pipes.
Tuneboy has test for stepper, not sure if axone can do this, both may show fault code for stepper failure. Hope this helps to understand. Just remembered tuneboy not available for benelli with walbro ecm.
 

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Hi caferacer the stepper on the 1130 engines are to control the fast idle (choke) only and not the tick-over. The 1130 engines have a tick-over screw as the stepper is completely shut once engine is up to operating temperature. The stepper on the 900 engine does control the tick-over as colintornado has explained, Hope this helps :)
 

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Hmm thats interesting Dodgy, but when i looked in the manuals it does still imply the stepper is controling the idle. The setting is lower than the 900, but if setting the co on tnt1130 it tells you to check the stepper setting as the mixture is altered, to make sure it is on 10 to 15, and it says it is constantly altering, therefore controling idle to some point ? Perhaps the setup has been changed and the manual I have is incorrect ??, If the stepper valve was faulty or stuck i think it could be caferacers problem ? Triumph 3s seem to have trouble with the stepper valve.
 

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Good reply colintornado, The latest info on the 1130 motor says to set the throttle bodies at full operating temp as the stepper is shut and this provides a good point to set the butterflies
 

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Discussion Starter #6
(you can see a white plunger that uncovers the little ports to the outlet pipes) mine is completely close,,, and if i try to push it down, it`s very hard,,, and when i turn the key on ,, the things turn and close it tight.. the weird thing i`ve notice,, is every time u turn the key on,, it tries to close it again,, never goes down.. thus always closing all the little ports to the outlet pipe ..

when does they open in this case?
 

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HI, obviously from what Dodgy says the setup is a bit different on the 1130 compared to the 900 motors, but if starting from cold I would expect the ports in the stepper to be open,even if they shut completely upon reaching a set temp. I dont think you should be able to move the plunger manually.
If the engine runs too rich from cold and is ok if warm and the stepper is shut all the time then the stepper seems the cause. If your bike is under warrenty a visit to dealer may be required.
Just read your other post about dealer ! If stepper is not moving,you could check conections etc and you could check as per the manual fault diagnosis.
 

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Discussion Starter #8
i don`t think the stepper would affect the bike fuel ratio at high revs,, when i turn the key on, i can see the piston in the stepper go up and close the port if i push them down before,, the funny part is that it only go upwards,, even if it`s already up,,, i mean, if i turn off the key and back on again,, the piston will try to go up again,, when already up... that`s weird.

i`ve found that my power commander is playing up,,, i could check the TPS with my laptop when plugging it to the PCIII,, when u accelerate,, u can see the throttle position from 0 to 100% move,, thus i assume the tps is ok... the problem is i can`t change the map on the bike,, and sometimes can`t even read it,, if i send the zero map,, its says uncompatible 136!> 186,, something like that.... i`ll remove the pc III tomorrow and try the bike again,, it should run lean, as the airbox mod.. as been done... we`ll see what happen.. if there`s a change in behaviour of the bike.. and the fuel ratio of course.

thanks for the help,,
 

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Hi guys, I found many topics about stepper motor, but I didn't find any answer why those air hoses from stepper to throttle bodies are plugged on my TNT 1130 -08?
I bought this bike last autumn and I made a test ride without any problems. It also starts nicely (at least in warm garage). Could this cause some problems in future, what's your opinion
 

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Some people have disabled the stepper by plugging the hoses to the throttle bodies and going for manual tickover adjustment. Which is mainly a problem when cold.
 

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That's done by people who don't know what they are doing. Put it back to standard and get the stepper working properly. It's likely seized, and rather than fix it, they bodged it. I had an RS here that had the same thing done to it. When I got it running again it would stall in the hands of the uninitiated, as many do, until I raised the idle speed by 100 and richened it up a little. It's been fine ever since.
Of course, the TNT has a manual idle speed control, so increasing the idle speed is a little simpler. To richen the idle up you'll still need an Axone or TuneECU, so you may as well raise the idle speed in the map at the same time, if it is prone to stall.
 

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Thanks for your replies. I think, I will check first if stepper is functional ( moving up when ignition on?) and then I try to connect hoses back to stepper and see what is the behavior.
If I understood correctly, problems will probably comes up when starting cold engine without this stepper which basically adjust a choke?
 

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... stepper which basically adjust a choke?
The stepper, a.k.a. Idle Air Control Valve (IACV) is much more than a choke. It is used to control the idle speed hot or cold. It also allows more engine braking since it can set up a complete shutoff of the throttle. A mechanical idle control can't do that.
 

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I finally had time to investigate stepper issue on my TNT and what I found was that there is no any visible movement at all on stepper piston when I switched ignition on. I also started my engine but still there wasn't any movement, so I have strong doubt that is the reason why hoses are plugged..
Is there any tricks try to fix stepper or just find a new one somewhere?
 

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I finally had time to investigate stepper issue on my TNT and what I found was that there is no any visible movement at all on stepper piston when I switched ignition on. I also started my engine but still there wasn't any movement, so I have strong doubt that is the reason why hoses are plugged..
Is there any tricks try to fix stepper or just find a new one somewhere?
Hi, I just bought a second hand triumph 955i stepper motor .A Straight swap for mine anyway and all my cold weird starting issues went away .
 

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Hi, I just bought a second hand triumph 955i stepper motor .A Straight swap for mine anyway and all my cold weird starting issues went away .
I was about to ask Triumph stepper part number, but then I found it from Engenia web page ( T1240888 ), thank you 👍

Is only difference that Triumph stepper piston is plastic, but if I order new Benelli stepper the piston is metal? (original on my bike is also plastic, but spare stepper has got new revision at some point?)
 

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I ordered second hand Triumph stepper and finally received it and then I installed it to my bike, but still no any movements when ignition is on or bike is running.. one possibility is already broken second hand part, but what else can cause this? Can I perform some measurements with multimeter to stepper or stepper connector to detect where the problem is?



Edit: I measured both stepper coil resistance and it is 50ohm between coil connectors. Then I measure voltage from connector when ignition was on, ~12volts for both coils.
After that I made a test with 9v battery and connect it alternatively to one coil of stepper and then other coil and yes I was able to move stepper piston by that battery.

So seems like a stepper itself it's not broken. Could there be some modifications done on ECU that stepper is disabled or is my ECU broken?
 

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Check the continuity from the stepper connector back to the ECU connector before you start worrying about the ECU.
 

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Check the continuity from the stepper connector back to the ECU connector before you start worrying about the ECU.
Thanks for your quick reply.
I think there is nothing to check with cables, because as you can see on photos, voltage comes till connector pins
36591


36592



Edit: checked also correct wire from diagram. English/Italy dictionary was useful..
36593


Is that some previous owner modification or what is that cross wired connector below seat?
36594
 

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Stepper motors don’t work by having a continuous feed. There are two coils and each can be powered with a different polarity, so by switching the polarity and the coil, it moves the stepper a very small amount each time. if You had a 2 channel oscilloscope you could watch the action.
 
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