And I'll give you a different perspective...

I would derive all of my analog stuff using precision reference voltages or current sources. I wouldn't want to have to know what the battery voltage was unless I really needed to. You might be able to figure out a way such that you do not care what VBatt was at all. :bulb:

I'm assuming there's a good stable (maybe even band gap) reference source used by the on-board A/D's and D/A's? There's no way they're using the digital supply for conversions, right? Use the same or another good reference source to drive the sensors and the battery voltage no longer matters.

You might still need to know when it comes to the injector pulse because the opening speed is so influenced by system voltage, but other than that, I'm thinking you shouldn't care.

Subscribed to this thread! This is awesome stuff. Sounds like a perfect upgrade to my Z.

@Captain.

Yes, the bat volts is only for offsetting any sagging/excessive voltage that the injectors see. I did connect the AFM reference voltage wire to an a/d input, but I'm going to use it for MAF or any other analog signal we may need/want from the engine bay.

@CG.

Your avatar makes me jealous. If only the bottom of my car looked that good.

General Status Update.

- I'm firing injectors. (well five out of six, something on one channel has an issue I need to chase down) Woot Woot!

- Just for grins, I did a quick code hack to make the pulse width vary linearly with the AFM input. This allowed me to watch the injector PW on the scope vary as I moved the vane in/out. It's obviously not accurate at all, but for me was fun to see some actual real world feedback. I do have all three Injection methods (MAP, MAF, & stock AFM) simulated and tested on the PC but without any base map at all to start with, or half way close AFM calibration numbers, it's a moot point to try them in the car yet. Plus, I have a lot of cleanup to do on the interrupts that fire the injectors & general testing. I'm getting closer though!!! I was shooting for New Years Day to have the first in car test, but I think that's slipped now.

Len

I was shooting for New Years Day to have the first in car test, but I think that's slipped now.

We forgive you.

Great progress! You should video your test vehicle running for the first time on your Hellfire system.

Just curious: Would coil-on-plug be possible with your ignition management version? I think you said lost spark with flywheel timing would be possible.

Well, you've put in a great effort. You may now take the evening off, but be right back to work on it tomorrow!

Sarah,

I will definitely video the first start attempt & post for posterity. No cheating, I'll post it as it's shot. I have a high confidence that it will at least cough, sputter, backfire, foul the plugs, or in fact even catch fire!

And to answer your question on ignition... The HellFire Hybrid will be able to do COP. You would of course have to use an additional ignition harness (will be supplied with the HellFire Hyrbrid version). This harness contains the inputs needed as well for the Crank position sensor, cam if desired, ect. I haven't detailed yet exactly what the ignition harness is going to look like, but it will exit out the back of the ECU case and have an appropriate automotive style connector & appropriate cabling/ends. TBD COP is the ultimate goal on my personal Z so when I get it dialed in, I will most likely offer a complete kit as well with all coils, brackets, exact lengths of cables, and plug and play connectors.

I'll be back on job bright and early tomorrow morning....or maybe I'll just write code all night.

Len

Nice! I look forward to seeing the video!

Happy New Year!

Really cool Lenny! I'm going to talk this owner into doing this upgrade by spring. I'll get him teased by making his car run ok on your "Donor" ECU then sell him on the benefits of Hell Fire!!

Que evil slow voice and fingers tapping together...."Excellent."

Thanks JR. I'm glad the spare ECU got you farther down the road. I've been watching the thread & your follow on ignition woes. It sounds like you're just about there.

Lenny

Just a quick update that I've done nothing on the HellFire for the last week, save for a tiny bit of cleaning up the code. I should have more time this week I hope.

Lenny

LenNY! LenNY! LenNY!

Go, Lenny, GO!

Hi Lenny,

I forgot about some accurate AFM voltage measurements I took on a working 77 280z. They are near the bottom of this page in the tables. I also plotted and modelled a curve and its compact equation.

http://www.atlanticz.ca/zclub/techtips/afm/sizeupgrade/index.html

Blue,

Thanks for the link to that curve. I had read that page before but didn't remember that a curve was there. This should help in getting a starting point/sanity check for a Voltage VS Airflow table. When I hook the Hellfire to my running car, I can generate the same curve. In theory, while the absolute voltage will be different because I'm feeding the AFM wiper with 5V, the curve should be the same (assuming both AFMs are both not tweaked too far away from stock) I'll post & we can compare.

I still want to do a good flow bench test of the AFM vs cfm, but for now I have other priorities with the code & building a flow bench will have to wait.

Lenny