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Post by redwoz on Oct 6, 2020 10:27:59 GMT
Hi Matt, Looking to use your project to power my ITB setup I'm building for a 1975 Holden Gemini. Plan would be to use 4 separate DBW ~44mm throttles, as I'd prefer not having to mess around with linkages/etc and having the performance gains of building a custom manifold to suit. Few initial questions: - what options would suit - i assume the PF-DI is the best/only choice considering the DBW
- what is the best way to control all 4 DBW throttles in parallel, as I see the PF-DI only supports 2
- is RPM vs TPS adequate for mapping for an ITB setup, or do I definitely require a MAP/MAF/AFM
- would i have access to the PF-DI source in order to apply my own modifications if required (more than happy to contribute should anything come of this)
I've built ECU's and done work on embedded systems in the past, so pretty keen to use something flexible and customizable where I have access to source code/etc. Look forward to your thoughts.
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Post by Admin on Oct 8, 2020 10:09:24 GMT
Hi mate,
PF-DI board has a 2 channel H-bridge motor driver but it can't be used for 2 DBW throttles because there are only a pair of TPS inputs and a pair of PPS inputs. Pairs are needed for each DBW and pedal (redundancy and error detection).
I guess you could control 4 DBW throttles with 4 separate controllers. To do that safely you would need at least 8 TPS signal wires so that can't be done with Rabbit ECU/PF-DI board :-(
Sure you can map against just TPS and RPM for an ITB setup. But I suspect you would need 4 separate fuel controllers in software because each DBW would never be as 'in sync' as 4 mechanically linked ITBs. Mapping off just one TPS might kind-of work but what if another DBW develops a 1 degree error? Or is slower to open and close? There would be a big difference in airflow at small opening angles between cylinders surely?
Sorry can't help a lot here - did you consider 4 mechanically linked ITBs driven by 1 motor and with 1 TPS that seems a lot less problematic!
Cheers,
Matthew
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