The Ace

Anyone tried something similar ? Just taking a digital or analog (even better) volt-meter, configuring it in such a way that it reads maximum 1volt, then connecting it to measure the voltage off the o2 sensor. If its digital then you have no fear of ruining the volt-meter circuit, if its analog you can even paint the face of the gauge red, yellow and green to match the three "areas".

Not sure how this will work, going to buy a variable volt-meter (for 9-10$) and check it out...

davo22

Paid the 60 for mine long ago.
Technically all aspects of the cars function could be measured by voltmeters. Good luck.

The Ace

Now that I have all the data about the various pressure and temperature meters on the car (and the corresponding wiring in the ECU), I'm even thinking about installing a cool multimeter with a good switch, and wire it up in such a way that I can select what measurement I'm seeing at every given point in time. That way I can constantly monitor temperature of oil and water, pressure of oil, water and turbo, bypass the fuel-cut etc etc...

Just have to figure out a cool way of doing this, so it looks good as well as perform very well...

lenny

I was thinking about the ideal of creating a box that would read the voltage coming off of the sensors and send the info to a laptop via serial port. This would allow datalogging, or maybe even output to a DIN-sized LCD display that could function as a digital gauge.

Im not very good with electronics, but I can program the computer interface. Anybody interested in this?

The Ace

Thought about it myself, maybe with a Palm or a nice multimeter (you dont need the data logging except if you are heavily modded), but it is too much...Probably I'm going to install a couple of small digital (backlit, if I can find them) LCD meters, and have one for the A/F (tuned to 2V max) and one for various temps (tuned to 20V max). Gonna cost less than 20 bucks, and be much more "presentable" than simply throwing around various gauges...

lenny

could you send me any info about how to read the voltages coming off the ecu? I have a 3rd gen, so I dont know if it is different or not. I do have a factory wiring diagram book which contains some information about the signals coming off different wires, but with my limited electronics experience, it is a little bit difficult to know what to do with these.

I am afraid of building a circuit that will alter these signals and then cause my engine to behave improperly. Like I said, I am not very good with electronics, but this sounds like an interesting project to get my feet wet.

Maybe I could even add a g-force meter to it to display lateral acceleration?

tesla042

http://www.ggimages.com/rx7/afmon.html

Let me know if you get it to work...We couldn't get it to scale right (but, we sorta threw it together slipshod... Apparantly, that guy has it working.)

Either way, that has some a/f ratios with cooresponding o2 sensor voltages.

-Tesla

Want2race

radio shack sells 1. It connects to a pc and oyutputs constantly
I would want it to read voltage for rpm and a/f....

The Ace

Hey lenny, if you simply measure the voltage, you dont alter anything. All you do is insert a wire in the appropriate slot and you are done. No cutting, no splicing. Even if the wire is loose and at some point in time disconnects, all you lose is your ability to measure the voltage. As far as the pin output is concerned on the 3rd gen, I dont know, but I can tell you that in the FC, the o2 wire is the 2C (second plug, third wire from top left). Other useful pins are 2B (AFM), 2E (Water temp), 2F (TPS), 2H (pressure sensor), 2K/2L (air temp). Except for the o2 sensor (which is between 0-1V), all the others vary between 0 and 4-5V.

tesla042, the wiring diagram is correct, and it seems to be working, but the proper calibration would be tricky, and the whole setup needs a good box, while with the LCD meter you dont have to do anything. Granted, you dont have the LEDS, but if you know the range of the voltage, you are set. And I think that the numbers are a bit different: 0-0,3 is lean, 0,3-0,7 is stichiometric (another greek word ), and >0,7 is rich.

peejay

This is exactly what I do.

Analog won't work unless you get a special high-impedance meter. O2 sensors don't put out enough amperage to move a typical low-impedance meter. I actually "burned out" an O2 sensor this way, by hooking it up to an analog meter. So I stuffed my trusty DVOM into one of the center air vents and used that instead.

Now, to figure out how to put backlighting in the DVOM so I can read it in the dark. The DVOM will tell you things a 10-LED meter won't. At full throttle if you see the voltage go from .975 to .950 to .925, you know your car is starting to lean out. The 10-LED meter will show you... no change. It'll tell you if your voltage drops to .800 or .675, by which point your mixture has leaned out to about 13-14:1 and you're risking your engine (turbo only).

The Ace

"Hey peejay, where's the base ??"....

had to say it, attribute to the old-skool rap scene...

Anyway, already bought two small LCD meters, one for A/F and the other for water temp, and I'll install them right under the AIWA and above the ash-tray. They'll fit nicely, and I also need a way to lighten them up... like peejay. One possible way is a line-led, like the ones they use to make lit letters for hotels (but very smaller of course ). another way is to use a couple of leds in such a way that they are out of sight, but they can illuminate the whole area. Probably one over each LCD...color probably blue or lite red....

booosted

I got one brand new that I was going to put into my car but just got a regular one instead. It is form a company in australia and it is meant for cars. Comes with directions. Some guy I know got them in bulk and sold it to me. Would be pretty cool if you mounted it just above the steering wheel or going down the a pillar. Lots for choices. Only $13 shipped to you. I almost threw it away. Directions are with it. Pretty good too. PM me if interested.

gorockrx

You guys should check these links out:


http://gadgetseller.com/gauges/


AND



http://www.dawesdevices.com/air.html

Check these out! Just what you were wanting and made in the good ol USA!

The Ace

50 and 55 bucks for a setup that I can do on my own for a lot less than 10$ ? COME ON.....This is exactly why I want to do it myself. I can understand when someone wants to charge me 100 or 150 bucks for a leather steering wheel or 50 bucks for a titanium shift ****. But not 60 bucks for a simple backlit voltmeter!! Nah, just going to do it myself...

The Ace

And I just checked out more thoroughly the GadgetSeller site http://gadgetseller.com...:(

99$ for a backlit AF gauge, that is practically a voltmeter Can you spell "highway robbery" ??
And 50$ for a battery voltmeter Man, either this is some kind of joke, or these guys are dreaming.... They must have ZERO activity in their PayPal account...

gorockrx

.....

You asked if anyone has done it before......thats what the links were for. Yes...the meters being sold are expensive because they are trying to make too much of a profit.......

Of course you can make them yourself. The idea was to look at what they are making and then.....
MAKE IT YOURSELF.....Duh!!!

You can make your own fuel cut defender, boost controller, and A/F Meter too......and you can get the parts inexpensively from lots of places.....if you know what to look for and IF you know what you are doing when you construct them. A digital meter is not necessarily low-impedance so check carefully. It's very easy to damage the stock ECU (or engine) with junk from Radio Shack. Good Luck.....

The Ace

...and the links were very much appreciated, but the prices there were like SHIIIIITTTT OMFG

I already knew what products were out there. I wanted to know if someone had anything similar THEMSELVES and tried it on his/her car...

Already made my own FCD (see sig.). Going to make an A/F and a Water Temp "gauge" this way. Dont think I'll tamper with the boost just yet...Waiting to have more cash on the side, in case something goes wrong...

Hey, I'm an Electronic Engineer, do you think I know what I'm talking about ? :p

gorockrx

OK.....I understand now.
Me a tech and you an engineer.....I should have know

You know how techs and engineers are......it's like speaking Greek to each other

Anyway, I have a custom A/F Guage custom made from an Autometer that is calibrated (replaced a couple of resistors in the guage) to read a much narrower range of .79 to .99 vdc. It is much more usefull and gives a good reading at WOT. I am replacing my regular O2 sensor with a 4-Wire Bosch to get a little faster and more accurate reading. We will see how that works out.

There are NO shops here that will tune a car, and I am not going to buy my own Wide-Band ($$$!!) so this is the next best thing. I may go ahead and get an EGT guage too (or make one?).

Here is my poor car right now.....just got my custom driveshaft back and now I am going to get the ACT Clutch/Flywheel combo from John at the store.....gonna be a pain to get that nut off of there again....Uggghhhh! I hope I don't pull my car off the jacks again....
I can't wait to see how it all works when back together.
I have custom made boost and fcd check valves so that should be interesting too. Later...

lenny

I would like to know how you "calibrated" your autometer gauge. I have an autometer gauge and i would like to do the same. What resistors do you have to replace?

thanks