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E-throttle and isc sol on a v12 engine, setup help

Tommy Luhr

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Hi! I'm building a Lambo replica and i have tuned a M120 Mercedes v12 engine with itb's on it. Engine is stock by now.

Running Bmw m3 Accutators/servomotors for the E-throttle, got two of this.  I got a own engine dyno and roller, trying to tune idle with this setup but it is hard to get stable without take some help from idle ignition. 

When i boost ignition at idle the engine missfires and there are some trouble to get clean exhaust gases.

Need to get perfect exhaust numbers to get pass the car inspection.

But my last idea is to only use E-throttle as servo assist for pedal and don't use them as idle control. Instead i mount isc solenoids and running them for idle control.

Running a Thunder on this and got room for adding isc solenoids.

When i setup this funtion in the software, "open/closed loop sol idle control" ask me if i got a 4 or 6 wire stepper. I thougth i could use 2 pin solenoids?

I think i will need one stepper for each bank of the engine, total of 2 solenoids.

Can i run two 4 pin stepper as paralell to one output? can the drives handle that?

I have never used 4 pins steppers before, maybe i cant't use them on the same setup.


What should you do in my situation?


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  • 5 months later...

I would avoid a stepper motor, but two solenoids connected to the same output should be fine - just check they dont pull more than 2A total.  

The common 2 wire Bosch ones from BMW etc would probably be plenty big enough.

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  • 2 weeks later...


Came across this by accident.

Guess your using 2 Banks of BMW S54 M3 ITB;s ?

On the std M3 set up the Stepper motor only works from approx 1800 rpm.

The MS S54 DME uses a cold air inlet valve for Idle and low rpm.

So the ITB's are shut until around 1500 rpm. [Emissions and idle speed]

As this CAV closes under load so the Stepper Motor takes over for the ITB's from  approx 17/1800 rpm onwards.

In Std Mode its almost linear from Throttle Pedal to TPS on the ITB's and then in Sport Mode its

around 75% TPS to approx 50% of Pedal.  [ I may still have the TP / TPS graph] 

Std M3 Throttle Pedal only opens the ITB's to something like 96%.

I am looking to do something similar with the M120/ITB's hence how I came

across your thread.






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  • 2 years later...

Hi! Back on this  after some time! I'm running motorcycle 1tb's. Could have done something similar to this setup as Bmw doing if i hade a way to make it work in the map. I don'r really want to tune the engine against pedal position. Why? 

With separate idle solenoid running as a throttle up to 1800rpm before itb's opening. There will be a custom table for this with ect as one axis and some sort of throttle position that make sense on another. Here is the problem. I mapped the engine after throttle main position (that way i can scale pedal position just how i want) I can't use that source to drive the idle solenoid first 6 procent of throttle. I have to be using pedal position to get this to work.

Are you guys se anuthing other way to set this up to get it to handle smoother?

I can ad a second idle valve just keep idle good. There should be an option for this in sw with egas. Turn idle motor to throttle before real throttle take over/add up on.

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