Ok. I'm new to wiki, so this is going to be a mess. This seems to be about the most reasonable place to post (I'm more of a forum guy).

I want to develop an open source engine piggy-back controller. The idea is very similar to your project here, except I want to minimize initial tuning by taking inputs from the stock ECU. My target application is the Dodge SRT-4. We already have 4 different very well tuned ECUs. Many hours went into their testing and I want to preserve much of that. However, I want flexibility to tune my engine based on my modifications.

So, the plan is to have inputs for the fuel injector and ignition drives from the stock ECU and modify them slightly as needed.

For example, adjusting fuel injector pulse widths to trim out excess fuel at WOT when using W/I.

I don't know if maybe I'm re-inventing the wheel and there already is such a project underway, or what... Perhaps a modified GenBoard could perform this task?

Anyway, if you really interested in details, check out my long-winded thread at srtforums.

http://www.srtforums.com/forums/showthread.php?p=2033955

The first page summarizes most of the project.

thanks. sorry for the mess.

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Doing that as a piggy pack controller seems both very cool and overly complex. I wonder if you'd be better off a) making a plug'n'play loom set to run a native VEMS ECU, or b) using a simple input (eg, MAF) interceptor to adjust fueling. Eg, [here] and [here].

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Thanks for the info! Good ideas.

A. I could run VEMS full stand-alone, but I don't really feel like going through all the re-tuning. I have a good tune as it is, I just want minor changes. Plus, I'd need to wire up a lot more sensors. Perhaps someday I will.

B. We don't have a MAF sensor. The ECU determines MAF from MAP, temp and RPM.

Perhaps what I might like to do is re-layout the GenBoard to change some of the extra injector drivers to be inputs instead of outputs. We only have 4 cylinders and it will stay that way. Also, change half the ignition drivers to be inputs. I'd also need to add some DACs. I'm not sure if I saw any on your design.

Is it possible to get copies of the schematics and PCB layouts in their native format? I'm not sure what capture program you are using, but I can probably get it or use it at work.

I'm an embedded software developer and I've done PCB layouts before. It shouldn't be hard for me to tweak your design to my purpose.

Thanks!

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Why not add control for 2 or more fuel injectors per cylinder.

This would allow for the accurate dosing at idle, but also give the capacity for a large enough dose to be administered while the inlet valve is open during the induction phase, thus enabling sequential injection right up to maximum rpm.

Combine this with an O2 sensor for each cylinder in the exhaust manifold, and we can potentially obtain close to perfect stiochemetric combustion on a cylinder by cylinder basis (and could also allow for better detection of misfires/burning oil etc).

This combination could also be able to detect and cope with injector failure and fouling problems, providing fault tolerance in the fuel injection system.