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undocumented routines, e.g. off idle position adder


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I’ve had a bit of experience working with several G4+ installations now. Something I have noticed is that there are things going on within the ecu that are not documented. An example of this would be the closed loop idle control, you get a certain amount of idle valve opening when the throttle is opened and you exit idle control. I'm guessing this is some sort of dashpot function however there is no mention of it in the user documentation.  For lack of a more detailed explanation, and having worked with different stand  alone and OEM engine management systems over the years,  empirically the G4 runs the engine very well, much better than many other other stand alone engine management systems I’ve used. Yet the user interface is fairly basic which, besides the idle valve adder that I mention,  leads me to believe there are other routines besides the idle control that are not documented. This would not be new within the standalone ecu market, as the old APEXi PowerFC’s had a lot of the control routines and related calibration parameters hidden and undocumented. I guess the philosophy could be that the manufacture figures reducing the amount of accessible calibration areas will make the tuning process more straight forward, which will also result in less customer support issues/costs. I would argue that it is a disadvantage, especially to experienced tuners that this information is not documented. I think it would be reasonable to ask Link to at least document these routines even if they are not accessible or editable to the end user within PCLink. It would also be an advantage to end users/dealers who request additional features withing the G4+ ecu.

 - Chris 

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Hi Chris,

You are correct, some functions do not have all possible settings, parameters, or information available to users. You have covered some of the reasons why this might be, another reason is to protect our IP. Generally I think we give a high level of detail of ECU functions in our documentation, many aftermarket ECU manufacturers provide nearly no support documentation. 


Edited by Scott
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  • 2 weeks later...

Scott, I understand your point, but I think in in certain areas, such as idle control, it makes sense to explain how all the routines work. Sure, for novice tuners your current approach makes it easier to digest, but what about your dealers or more advanced users who are used to and need full understanding and access to address and resolve tuning issues. 

As a start, could we add some additional idle related ram variables:

- base idle valve position

- P, I, D, and anti-stall corrections (I know that there is know description of a Integral gain, I'm just assuming it's undocumented)  

- the "hidden" idle position offset

 - Chris

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Hi Hexdmy,

what you are referring to I have a work around that most people use.

I use the Idle Ignition Table to overcome these issues.

With setting up the base throttle blade air gap and base chosen idle timing,i adjust my setup to the point of being able to totally do away with idle controllers completely.

There are many different processes to this but it is very simple.

I tune a lot of twin turbo Big Bloch Chev Race boats, these things run approx. 6" Hg at idle,

Through my setup process without any idle speed controllers, we can start these engines dead cold and have beautiful ide and pull the trans into low or second gear, (HIGHLY MODIFIED TURBO 400'S converted to 2 speed, NO TORQUE CONVERTORS, Just a direct drive plate setup.

Without any RPM change indicated by the MoTeC DASH or by feel or ear.

However your suggestions are fine, but sometimes these types of requests will not be prioritised due to the low volume of requests.

However all requests are governed by LINK themselves.




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  • 6 months later...

Hi Dave


Do you find doing the throttle ajar method reduces booster performance?


And 2, how does idle ignition control function any different to having ignition table columns for example 0, 400, 900, 1000 in your ignition map at -50MGP row reading 15 for cranking, 25 to raise idle drop, 20 for idle, 22 for acceleration takeoff, and with idle ignition control eliminating cold start trims, is that really a good thing? must one really waste a table allocation for this?






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