The carb computer

[A20A1]

Well I've been dabbling into programming for windows... and I got to thinking what if I make a program to at least map out readings from:
- Wideband A/F gauge
- RPM
- Fuel PSI
- Manifold Vaccum hg

*Dependng if the Carb has ports for these*
-- Pri-Sec Port Vaccum hg
-- Pri-Sec Throttle Vaccum hg
-- Pri-Sec Venturi Vaccum hg

*If I can get the basics working I may add this*
--- Throttle Position Sensor

Problem is I can do simple programs in windows... but I have no clue how to make something that will give output and how to make a program that will interpret the input and then display it.

I was basicly wanting to make a carb tuning box... that will then need a laptop to be useful or I guess it could store the data somehow so you could move it to the desktop.

I know digital vacuum gauges exist, and wideband O2's I can get, I already have a tach... I just don't know what I need to pull data from the voltage singals thay put out.

Any help would be appreciated

[mouchyn]

i don't understand the purpose of such a device. is this just for data collection so you know what adjustments you need to do the carbs?

it almost seems easier and cheaper to move to FI... then you have reliable, tested, documented, and inexpensive tuning tools available already.

[A20A1]

I know programs like this exist but I want to know, you know. Like how to build it a make sure I can add new sensors and adjust the program accordingly. With someone elses system you get what you get most of the time and then you're stuck with no way to add more sensors for specific outputs.

[A20A1]

i don't understand the purpose of such a device. is this just for data collection so you know what adjustments you need to do the carbs?

it almost seems easier and cheaper to move to FI... then you have reliable, tested, documented, and inexpensive tuning tools available already.

Yes it's to help carb tuning.

I also wanted it to test other carbs, larger ones, so I know if the carb is simply too big or if it simply needs a little fuel adjustment.

I see your point about EFI, but I'd rather stick with carbs.

[mouchyn]

well, something like a pocket logger will read and record anything the ECU takes inputs from.

beyond that, things like fuel pressure and vacuum pressure can be monitored with standard gauges. those aren't really variables you need to monitor full time.

what other kinds of inputs/sensors would you need to monitor on a carbed motor?

[A20A1]

...beyond that, things like fuel pressure and vacuum pressure can be monitored with standard gauges. those aren't really variables you need to monitor full time.

what other kinds of inputs/sensors would you need to monitor on a carbed motor?

But I'm thinking with a carb Vacuum is a full time variable cause it's what the carb needs to run.
If venturi vacuum is too low at certain RPM's then you know you need to get more restrictive venturies / booster venturies or simply drop the bigger carb for a smaller one.

A tps readout would be nice maybe two tps's one for the primary throttle and one for the secondary throttle... they you could manualy adjust when the secondary opens and see how that affects things on the readout.

The problem is I can't monitor everything with standard gauges cause it will be too much to look at all at once. I'd like something to print onto a graph or table.

[A20A1]

well, something like a pocket logger will read and record anything the ECU takes inputs from.

i'm working from scratch though... I doubt I can pull anything out of the stock carb ECU which probly isn't even an ECU, more like a simple control box.

[mouchyn]

well, tps voltage, O2 sensor voltage, vacuum control valve control, RPM, and some other things can be taken from the ECU. you know those wires go right to the ECU -- even if you tap the wires before they get to the ECU. that's what feeds into the pocket logger.

as for carb vacuum control, you would have to use some kind of digital vacuum gauge for every source. that could get expensive...

[Vanilla Sky]

so, you basically want to set up an OBD system for the carb? i would start looking at places like www.mouser.com and www.allelectronics.com and other electronics and electronics surplus suppliers for parts... if you need help sourcing harder to find parts, PM me and i can help

[AccordEpicenter]

i like your idea a20a1, im sure you can do it, im not sure how well its gonna work though. If you really want tunability/driveability your still not gonna beat efi though.

[A20A1]

You guys. This isn't for controlling the carb really.
It's just to get a easy to read display of the voodo going on when you press the gas.
Assuming I have the funds, I could tune a carb just fine running a few road tests... but not everyone knows what to look for, and when you can't drive the car it's hard to diagnose whats going on quickly over the net.
I'd like to provide a visual aide to help with carb tuning.

[mouchyn]

well, you're either going to make the computer for yourself or you're going to make something reproducable so other users can benefit from it.

if you're doing it just for the sake of learning, that's awesome. more power to ya. we can help you figure it out.

if you want to make something reproducable, i think it might be a pipe dream. i'm sure most users would rather spend money on other parts/mods.

if you just want typical scenarios for accord carb tuning, you could look around the internet at other car sites that use engine sizes and carbs similar to ours. i'm sure they have already provided graphs, information, and tuning techniques...