V8 independent throttle bodies controlled by single E-Throttle actuator

[DerekAE86]

I've got a project on the backburner that is utilizing the 8 Throttle setup from the S65 BMW engine (from the E9X M3)

Typically these engines have an actuator to operate each bank and then an external TPS on each bank.

I am planning on fitting a single modifed Bosch E-Throttle that will operate both banks at once. My question is - what would the best way to go about the TPS1/2 signals?

I'm thinking leave the Bosch unit's potentiometers disconnected (so just provide it Motor +/-) and wire TPS1/Main to the bank1 sensor and TPS2/Sub to the bank2 sensor - that way the ECU could detect if one bank was different to the other due to mechanical failure of a single linkage, or if neither sensor was showing a movement when a motor drive signal was commanded due to mechanical failure of both linkages.

If done this way should one TPS be wired backwards so one bank1/main signal would be closed 0v -> open 5v and bank2/sub be closed 5v -> open 0v for example, or would that not matter?

I guess one of the Bosch unit's potentiometers could still be wired up to an analog input just so it's positional data is also captured.
But I'm not sure what you could do with that information.

[Adamw]

A sensor on the motor and one on the throttle shaft typically doesnt work because you need a near perfectly linear relationship between sub and main, and linkages that work in an arc rarely give a linear relationship.  

Provided the linkage to each side is close enough to mechanically identical then you could probably get away with a TP sub on the throttle shaft on one side and TP main on the other side.  However, I would probably just put a dual track TP sensor on one throttle shaft to keep it simple.  

[DerekAE86]

So in reality to keep things as linear as possible it'd be better to just not connect the individual TPS's up at all and just wire both signals to the Bosch EThrottle like in a traditional single TB setup?

Adding onto this - if I find that one motor just cant do it and have to go to two motors the G4+ Thunder is the newest ECU in the Link lineup that could handle that right? Nothing in the G4X range had dual Ethrottle?

I see the G5 features show it. Is it still tracking for a 2023 release?

[Adamw]

9 hours ago, DerekAE86 said:

So in reality to keep things as linear as possible it'd be better to just not connect the individual TPS's up at all and just wire both signals to the Bosch EThrottle like in a traditional single TB setup?

No, the sensors should be on the throttle shaft(s), this is the important variable to monitor for safety and you get better control without the linkage backlash in the feedback.  

9 hours ago, DerekAE86 said:

Adding onto this - if I find that one motor just cant do it and have to go to two motors the G4+ Thunder is the newest ECU in the Link lineup that could handle that right? Nothing in the G4X range had dual Ethrottle?

Anything from the Storm up can do it with the external module.  

[DerekAE86]

On 7/30/2023 at 9:24 AM, Adamw said:

However, I would probably just put a dual track TP sensor on one throttle shaft to keep it simple.  

Any suggestions on a dual output sensor?

21 hours ago, Adamw said:

No, the sensors should be on the throttle shaft(s), this is the important variable to monitor for safety and you get better control without the linkage backlash in the feedback.  

Would it be viable to have Main/Sub wired to the motor but wire the the shaft TPS wired to a spare analog input and use that as the tuning axis rather than TPS(Main). That way you wouldn't get any play in the linkages messing with the actuator's target/PID settings, but you still get the accurate throttle shaft position?

21 hours ago, Adamw said:

Anything from the Storm up can do it with the external module.  

Honestly I'd prefer to have an all-in-one solution with dual DBW and dual Lambda controllers rather than rely on more external boxes at this stage.
Think I'll just wait for the G5.

[Adamw]

2 hours ago, DerekAE86 said:

Any suggestions on a dual output sensor?

XPD-2832-811-214-911-00.

 

2 hours ago, DerekAE86 said:

Would it be viable to have Main/Sub wired to the motor but wire the the shaft TPS wired to a spare analog input and use that as the tuning axis rather than TPS(Main). That way you wouldn't get any play in the linkages messing with the actuator's target/PID settings, but you still get the accurate throttle shaft position?

It would possibly work, but there is a lot of engine control stuff linked to TPS and TPS delta, as well as you really want the ecu to monitor throttle position rather than motor position from a safety point of view.  I have always found it best to use the throttle shaft sensor(s).