DIY AF Ratio Meter

[defcon1]

Starting this project. Actually very easy to build as the whole device is based on a single IC. I did it once before, but lost my notes so am going to have to research it again. Shouldn't take long as I know what to look for.

The final device would simply consist of a small pcb with a row of LED's consisting of 3 colours....red (lean), green (stoichiometric), yellow (rich)...

As for connections...simply connect to an existing O2 sensor...or if you are worried about tapping into the, by now, brittle wiring...get a second hand O2 sensor from the scrap yard and drill/weld a mounting into your exhaust...in front of the original cat converters.

It's the exact internal mechanism that you get when you buy an after-market AF Ratio meter for RM 250 - 400.

Heh...with 2 units...you could independently monitor both sides of the V...

 

[honggas]

Hehh ... so many DIY la Deffy .. when are you going to teach us DIY 5 litre V12 engine for ceffy

 

[defcon1]

Oh...that one ar...too easy lah....

Just drop in 2 V6 motors into engine bay...each with one drive shaft only...one for left wheel and one for right...and you have a V12...

 

[honggas]

Then based on the setup, we get something more than what we aim for .....

a V12 6 litre engine

Hehe .. jokes aside, forgive a young foolish padawan for asking, since the end product allows us to track the air fuel ratios, err what do we do with the information.

Sorry if the question is too simple, I really have no idea ...

 

[defcon1]

Well...allows you to fine tune your engine...keeping your af ratio at stoichiometric means your combustion is at optimum, so...cleaner engine, better torque, and better FC...

Also, for modders like me, I have a fuel pressure much higher than others...so, it helps me tune plus...if I add a safc...I can retune the fuel curve with great accuracy...

Plus...it looks cool on your dash...lol...

 

[honggas]

Well...allows you to fine tune your engine...keeping your af ratio at stoichiometric means your combustion is at optimum, so...cleaner engine, better torque, and better FC...

Also, for modders like me, I have a fuel pressure much higher than others...so, it helps me tune plus...if I add a safc...I can retune the fuel curve with great accuracy...

Plus...it looks cool on your dash...lol...

Ah, so if I were to utilize this great innovation of yours Deffy, then I would also have to learn the tuning part frm you ...

Any case, the "looks cool on your dash" part is really tempting ...

 

[defcon1]

Looks cool on your dash...heh...execution is important...

 

[defcon1]

This is what I intend to build. Anyone can help me with the components?

Parts List
1. DOT/Bar Display Driver - National Semiconductor LM3914N
2. Voltage Regulator - National Semiconductor LM340MP-5.010
3. 18 Pin socket
4. 20 Pin socket
5. Segment LED BarGraph (never seen this here. Can replace with a row of LED's but a BarGraph looks way nicer and more professional.
6. Multi Colored LED (GGGYYYYRRR)
7. Resistors (2.3k and 3.3k)
8. Mini Circuit Board
9. Misc Wires - probably lying around the garage / house.

Optional Parts:
2x 4.7k Ohm Potentiometer

Data Sheets
National Semiconductor LM3914N
National Semiconductor LM340MP-5.0

And this is what it is supposed to look like when complete. The unit on the left is the home-made unit, and the unit on the right is a commercial unit.

The most difficult part would be basically the soldering. I hate IC's...cos my eyesight is not what it used to be... :sad_smile:

 

[honggas]

The most difficult part would be basically the soldering. I hate IC's...cos my eyesight is not what it used to be... :sad_smile:

I was told by some electronic major friends of mine while I was studying, that there are some shops in Jalan Pasar which solder the parts according to your diagram for you.

Don't know how much they charge though

I would love to help, but never really hold a solder before.

 

[defcon1]

No no...that's not diy...that's diu...do-it-for-U!!!...

 

[honggas]

No no...that's not diy...that's diu...do-it-for-U!!!...

Ok ok .. see whether I can find someone who can solder things without burning their hand like I did

 

[defcon1]

Borrow Ong's gloves lor...

Just had a chat with my service dept manager. He'll look out for those components for me. Worst case, get my friend from SG to go find some and mail them to me...

 

[wizardboy]

can find it in m'sia la.

 

[defcon1]

If I had the time to go look for it, can lor...

But if you work 12 hours a day, 6 days a week like me...easier to get friend to get it for me from Simlim along with other things I need and mail to me...

 

[honggas]

If I had the time to go look for it, can lor...

But if you work 12 hours a day, 6 days a week like me...easier to get friend to get it for me from Simlim along with other things I need and mail to me...

To add to that, seems like you're spending another 12 hrs on your DIY stuff

Err .. you no sleep ka Deffy? Or you simply have more than 24 hrs a day

 

[wizardboy]

hang on, i asked my r&d engineer, there's a website (m'sia) where u can purchase all this components. i'll be purchasing 2 unit (estimate ard 50 ringgit for both).

 

[defcon1]

Er...sleep?...what's sleep?...

But seriously...I wake up at 6.30 am, get to office by 7.40am, leave the office anywhere between 8.30 pm and 10pm, Mon - Fri. Sat can be half a day or a full day depending on situation. So, by the time I am free to do things, Jln Pasar is already closed... :sad_smile:

 

[defcon1]

hang on, i asked my r&d engineer, there's a website (m'sia) where u can purchase all this components. i'll be purchasing 2 unit (estimate ard 50 ringgit for both).

That would be good info to have, Wiz...