The center LED is approximately 14.7:1. DO NOT try to assign AFR values to the LED's. If you want something accurate, save your money and buy the LM-1 or build a DIY-WB. This meter is merely meant to give you a better idea of what's going on and how your ECM operates. It will help you in tuning, but it will NOT give you exact or even approximate AFR's other than 14.7:1. It simply follows the stock sensor's curve more accurately than any current aftermarket meter.

Keep in mind that the rich area changes in coordination with EGT.

 

Keep in mind that this is *not* a wide-band O2!!!

 

What email/account should I send the paypal to?
Ed

 

Can you run it on the same O2 sensor the system is using?
No problems with an additional load on the signal?

 

ken7382@hotmail.com

 

Yes, you can run it with the ECM - that was the idea behind the design in the first place. Most other AF meters put a small draw on the O2 sensor and it screws with the ECM. Ours does not.

 

Just reading some new posts on the A/F meter.

What I wanted to ask is if you are LEAN will all 10 LEDS light up on the LHS and if you are RICH will all 10 LEDS light up on the RHS?

Or will it depend on how LEAN/RICH you are that maybe only 1-10 LEDS will light up?

I think maybe this is what Mangus was talking about?

So if I am only a little lean will all 10 LEDS Light up or will only say 3 of them light up?

 

No.

Yes. That's the whole point of the meter in the first place. To give you an idea of HOW rich or HOW lean you're running.

 

Sweet I was not sure after reading all the replies Can't wait to get mine woohoo.

 

Found a A/F metrer here for sale but going by the description not really sure what it is capable of. Also seems to be set for a specific EGO Probe. Just thought I would post it up for you guys to have a look at it.

A/F meter

 

Yep, I actually *bought* and *assembled* that one. Not only is it just as inaccurate, but it also updates VERY slow; about twice a second. For that price - what's the point?

 

Hey Ken, my PCB was delivered Saturday… pretty sweet, thanks… now only to find time to work this in with the rest of my projects…

 

Just a new note:

I made it up to Grumpy's this weekend and paired my AF meter up with his DIY-WB (do it yourself wideband, for those of you not familiar.) While it was obviously nowhere near as accurate, it was definitely adjustable to where it probably will be semi-close. The resistor values for the gap and top/low end in reality aren't "set in stone" (hence the spreadsheet.)

I *KNOW* they need tweaking to be a little more accurate, but I'm going to need use of a wideband to get it close. The good news is, it's just a couple of resistors that are easy to solder out/in.

 

And this is using a narrow band lambda? Heh, cool… I was just hoping for something that would give me a hint of where I was at, something approaching accurate is a bonus. I’m not sure why no one has ever tried to do something that scaled with the output curve of the sensor before, seems obvious.

Keep us updated on the new values, I suspect that it will be a couple of weeks before I have time to assemble mine, so I might as well go “latest and greatest” with it.

 

Keep in mind, that the output of a lambda O2 sensor varies significantly with EGT, so resistor values developed one particular car may not necessarily carry over to others.

What would be better, is to compare it to a WB on the actual car it's going to be used on, to get an idea of how it compares. Even then, keep in mind that the limitations inherent in lambda O2 sensors still apply -- Ken & Bill's meter is cool, but don't expect it to make a NB into a WB!

(BTW, got my boards, and ordered parts last night )

 

Not always! Lots of digging and research.

Dave is very correct about EGT affecting the sensor curve, but it's generally the upper (rich) portion. We might make a compensated one later, but it's STILL not going to be accurate like a Wideband.

 

Here's a chart that pretty much spells it out.

From "Internal Combustion Engine Fundamentals", by John B. Heywood.

 

Question about assembly,


Do all these capacitors have polarity?? Or can they just be placed in either way.

 

Guys,

Quick question about assembly of this unit.... I finally got around to soldering everything together and when I powered it up the only LED that lit was the center 'stoic' LED? Is this working properly or should all the lean LEDs light up with power to the board but no O2 sensor connection? I haven't had a chance to hook it up to the car yet, so I'm just wondering. I triple checked all the solder points and everything looks good.

Thanks for any help,
Rob

 

sounds like you got some LEDs in backwards, the green and red are opposite mounted.

 

Oh, so the led's have to go in in a certain direction?? I didn't realize there was a positive and negative leg. How do I determine which way to install them?

Thanks,
Rob

 

http://www.interq.or.jp/japan/se-inoue/e_diode.htm

 

Thanks guys. I put all the LED on the board in the same orientation so I'm sure I have all the 'lean' LED's backwards. I'll get some more and put them on in the other direction and I'm sure it will work fine then.

Thanks,
Rob

 

Just switch 'em around. You didnt blow 'em up.

 

Your BOM is for 10 yellow leds but your pic shows 10 green and one yellow besides that I'm gonna use a sharpie to blacken them it reduce blled through. Kewl meter the pcb is a bit fineky when soldering.
Ed

 

For dealing with the LED bleed through, I ended up just using some black enamel paint on the sides of the LEDs. Doesn't take that long, and seems to work better than an ink marker.

If that's not enough, glue on some squares of metal foil

 

I just used a Sharpie. Worked fine for me.

It's definitely a pain to solder, an Optivisor or loupe helps immensely in making sure you don't have bridges.

The BOM discrepancy is just a color preference; Bill wanted 10 yellow, I wanted 10 green. (Green for power, red for lean.) You can use any color combo you want; green in the middle, red on the ends.. it's entirely up to you.

 

Just one last question on the LED polairty... On the LED's, one leg has a flat depression while the other does not. It this leg the anode or cathode side of the LED? I can not go by length of the legs since mine are already cut.

Thanks,
Rob

 

Easiest way to find out is to put it on a diode checker...

 

Yep, put a DMM in "diode" mode and put it across the LED leads...when the LED lights up (very dimly) then the positive meter lead is on the anode and the negative lead is on the cathode. The "depression" on the leads means nothing.

 

WTB a kit or two. Are they still 40 shipped and how many do you have avail can would you do 3 for 100. A buddy saw mine now he wants two.
Thanks
Eddie
P.S. These are great visual feedback for SOTP tuning lol
Edfirebird68@aol.com

 

Ha, I dumped $140 or so when I had to buy that book (in hardcover) for a couple of classes, and other than that O2 table, its worthless. It has no thermodynamic cycle analysis to speak of (of ANY of the cycles diesel/otto/atkinson/miller), ignores geometry factors such as bore/stroke and rod/stroke, and doesn't really hammer home the point that (ideally, with no tuning issues) the peak VE point is the peak BMEP point is the peak torque point. That book is one expensive door stop.

I kinda want one of these kits but it'll be a couple weeks and I have a question: Is the output of the sensor a log function, or is this setup just sort a good approximation to get started tuning with?