DIY Air Flue Ratio Meter
Turbo Mini Forums

I don't really have the cash to splash on a fancy gauge, so something being better than nothing i am going to have a bash at making my own.

After a spot a research i thought i would let you guys in on the not very well kept secret. I am no electronics wiz all this info has being pulled from various websites so all this could be waste from bulls!

List of parts needed:

10X LED's 6 red 2 green and 2 yellow 50p each

10X LED holders 25p each

2X 2k ohm resistor (red black red gold) 17p each

1X 1N4007 diode 16p

1X chip LM 3914N £4.70

a small section of blank circuit bored stuff £2 ish

few bits of wire

a nice box to mount the lot in, i will be mounting the LED's straight into the dash and the gubbins in a box behind them.

All the bits are available from Maplin.

and this is how to wire it all up:



you want the LED's in this order running from left to right, RRRRRYGGYR


This is the Lambda i have, i think it is from a mpi mini. It has 4 wires i am not 100% but i believe Black is the signal the the meter, Grey is earth and the other 2 are the heater wires. This is where i become unsure and need a spot of help from you guys...

Do i just run a 12v feed to one of the white wires and earth the other? I don't think if it was wired into a ECU it would be heated all the time, so can i run the earth to a switch on the dash? (switched on meaning it is allowed to be earthed) and will it matter witch is witch? I think not as they are the same color.

Also dose anyone know of the top of there head the thread size of this baby?



I am off to Maplin tomorrow to pick up the rest of the bits if i am allowed by the Mrs. If i am very lucky i may get chance to wire it up and stick up some more picks.

Thanks for any help and please let me know if i am talking out of my ass?

Someone posted up recently some links to a cheap wideband solution with a display.
In my opinion it's worth spending a bit of money on a proper wideband to see everything is ok than having to fork out for a new engine.

mac , you can do it a bit cheaper , get a digital voltmeter ,and just read off the black wire in millivolts .anything nr 1 volt is richer than 14.7, anything lower than 500 mv will be in the leaner than 14.7 area .

this sort of sensor ,you can connect the white wires to 12v and earth , it doesnt matter which one of the white wires goes to which.

another choice for greater accuracy would be a wide band sensor from jaw .

this sensor your using will be usefull in that it lets you know if your richer or leaner than 14.7 :1 but apart from that its a bit limited ,but definately better than nothing .

regards
robert

Edited by robert on 13th Feb, 2010.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

[quote=maccamcvey,13th Feb, 2010]Also dose anyone know of the top of there head the thread size of this baby?
quote]

M18X1.5 I think.

Luke

Sturgeo, i did come across that thread and it seams the conclusion robert came to is the link at the bottom is the cheapest. Dose a wide band sensor work the same way as a narrow? kicking out between 0-1v? if so i could use one of these with the same meter.

robert, i hear you want between 12.5 and 13:1? the problem with the meter i have the plans for i have no idea where this will be at the moment. its obviously intended to be when the green led's are lit, and its not gonna be hard to switch them around once i have being on the rollers and know where it is. It would also make sense that there being 10 led's and 1v each led would be 100mv but this is pretty useless because i dont know what 0 and 1v is lol

and cheers luke

http://www.amazon.com/Bosch-17014-Oxygen-S...04800291&sr=8-1

luke ,the narrow band sensor is a little like a switch ,anything a bit richer than 14:1 or leaner than 15:1wont change the voltage much,.

it varies from sensor to sensor ,but to get an accurate setting in the 12:1 ranges ,youll need a wideband ,which i think uses a a 0-5v range.if i remember correctley .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

The output from a wideband system is typically 0-5v, but this is conditioned and can be set to what you like. As for how to condition it I have no idea.

Out of interest I am about to get my NA998 back on the road and want to do some DIY tuning. I have a narrowband and a wideband, but am a bit nervous about using the wideband on a carb'd car. What is the risk, can it kill the sensor?

http://www.twin-turbo.co.uk
http://www.hillclimbandsprint.co.uk/default.asp

A man without a project is like a like a woman without a shopping list.

that lambda from a rover is a narrow band, ive been replacing the one on my other car, i presumed it was a wideband, but it appears it isnt

Wil, i would have thought you would be fine using a wideband on a carb car, are you using any additives though?

Edited by Nic on 14th Feb, 2010.

The wideband sensor needs some sophisticated electronics to get a 0-5v signal. The sensor alone will not do that.

The AEM gauge comes with the controls in the back of the gauge, whereas, Techedge or Innovate have separate controllers.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Try www.14point7.com

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

top link cheers mike, may have a bash :)

Hi, why don't you call David Hampshire @ Canems Engine Management Solutions 01724 331688 or 07903 396294 & ask him about the stuff you require.
David has developed an fully mappable ECU etc for the Mpi & Spi Mini & can supply most of the bits you'll need or tell you who to buy which bits from for your AFR meter & display & he's not too expensive either.
I'm using a wideband lambda sensor (which you will need) & an Inovate LC1 which is the interpolator needed to send the correct signals for the ECU to read but your LC1 will send signals to your display. I bought mine from Burton Power 0208 5189136, controller & sensor 3769 for £150 in June 2008 so it'll probably cost more now.
The lamda sensor Bosch number is 930VW1120 which is used in the VW Caravanette I think but you should be able to 'google'it to find out which vehicle it was used on, then you'll need to drill a hole & weld a boss into the exhaust which you can get from Canems. Cheers, Laurence.