In SX Microcontrollers, SX/B Compiler and SX-Key Tool, RinksCustoms wrote:

Okay i know most of yall r a bit sensitive to critizism, but i'll try to be constructive... and i would like to formerly welcome you all to my thread i'll be starting on my version of a DFI in the Propeller forum.

Awesome effort here guys!! Good points made in this thread and there were some helpful formula's over on the BS2 linked thread. Both SX and BS2 ECU's would benefit greatly from a "wide-band" O2 sensor however, allowing precision readings that are alot more linear than the "cheapy" O2 versions. Think i'm full of BS? Look up the datasheets for a standard "cheapy" O2 sensor and look at the linearity curve for voltage vs temp, it's a joke for reading stoich smoothly! The curve is so steep it's more like a high-speed comparator than an accurate thermocoupling device, yeah T/C, it doesn't sense Oxygen levels at all in case you were wondering. It's just a calibrated "high speed" thermocouple, and the cheap ones are a poor one at that. 

A Wide-band version may cost more but the temp/volt curve is ALOT more linear giving you alot more presision that leads to a smoother running, better responding engine. I have a Buick Grand National on the stock ECU/block reading a wideband O2 provided through a bit of electronic conditioning and it runs very smooth, even if you "smack" it to the floor, currently the car is in the low 11's runing an 11.1 @ 121MPH w/a 60ft time of 1.5 sec, that's ~avg 550HP, i say average cause i was on/off the gas all the way down the 1/4, it's never been dyno'd, only calculated. I know now after looking at the numbers that the turbine housing was a bit small "choking" the engine causing it to break-up and mis-fire.

75MHz is not overkill for EFI, in fact, it's what most aftermarket DFI's are running close to, some are running @ 120MHz core speed "xFAST FI" or DFI i think it's called, it was at SEMA last yr - (Digital Sequential Fuel Injection). 

Please view my thread in the propeller forum on this project, or subscribe to it if you like. But i'm almost expecting some critisism on my efforts, I'm hoping all your suggestions will inevitably lead to improvements as a set of fresh eyes will always have a different point of view.

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