exhaust gas analyzer.. buy or make one?

Obin Robinson · 05-01-2001, 11:19 AM

hello,

i KNOW FOR A FACT that the air/fuel is off in my 924. i also know how to adjust it, but i'd like to use an exhaust gas anlyzer to make sure i am getting the most precise mixture.

question: i'd rather not have to pay $1000 for one, and i know that i've seen plans to make one using an oxygen sensor and a voltmeter SOMEWHERE a long time ago.

anyone have one, or know where the plans are to build one. i think someone posted a link to a volvo or saab forum where someone said how to make one.

thanks!

obin

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A straight line is the most BORING distance between two points.

wolfrpi · 05-01-2001, 11:40 AM

4 wire O2 sensor and air/fuel gauge from just about anywhere (Halmeter, EFI, Autometer). I have a Halmeter if you are interested.

Erick

Obin Robinson · 05-01-2001, 11:43 AM

do you want to sell it or can I borrow it? also, it doesn't matter which 4-wire oxygen sensor... like one for an AMC eagle, or a Lamborghini Diablo... they'll all work the same?

thanks!

obin

[This message has been edited by Obin Robinson (edited 05-01-2001).]

[This message has been edited by Obin Robinson (edited 05-01-2001).]

wolfrpi · 05-01-2001, 01:59 PM

They work Excellent! The extra wire on the O2 is a ground which improves the accuracy of the signal. Jason at Paragon has them for about $40. You can have my halmeter for $50 if you're interested.

Erick

Obin Robinson · 05-01-2001, 02:08 PM

hmm, i might just take you up on that offer.

which halmeter is it?

thanks!

obin

vas deferens · 05-01-2001, 04:23 PM

How does the 02 analyzer get hot enough to function if your sticking it in the tailpipe? Unless you temporarily replace it in the same spot as the original O2 sensor for testing purposes.......what if one of you fine young automotive scholars were to provide the wiring schematic with the directions on this BBS. I would be interested in trying this......anyway it would only measure O2 and how would you measure NOX and CO2 like the "real machine" does?........this would be a great item to have in the garage if it flies.....Curious in Hawaii......

kaffine krazed · 05-01-2001, 10:41 PM

To tune an engine you should have at least a 4 gas analyzer CO, CO2, O2, HC, and get the exaust before the cat. I don't think a NOx analyzer would help much unless you have a dyno. You might want to call around and see if there are any shops in your area that have a dyno and an exaust analyzer. I belive the dynos around here charge between $100-150 for an hour.

If you just want to use a voltmeter and a O2 sensor just use the stock O2 sensor if you have one. All you need to do is hook your voltmeter up to the signal line and the ground wire if present if not then just ground the other end of your voltmeter to the engine. Most O2 sensors vary between 0V and 1V you want it to toggle above and below 0.450V if I remeber correctly it should be above 0.450V more than below but you still want it to toggle above and below 0.450V.

vas deferens: Do they check for NOx in Hawaii?

AMCPorsche924Powerhaus! · 05-01-2001, 10:52 PM

if you have an oxygen sensor model of 924, then all you need is a dwell meter.

don't know how much they cost, about 20 dollars maybe.

924.org has some posts on that subject up at the top i think.

wolfrpi · 05-01-2001, 10:53 PM

The 4-wire will be fine for an N/A. It even works exceptionally well on my 951. If you want to be real precise about measurements and look for an extra maybe 5 hp go to a dyno shop and get a Horiba o2 sensor ($4,000) hooked up for precise readings. On a non-programable car though the Horiba won't help much because you can not vary fuel tables at different rpms and loads as you can with many of the Japanese cars. On Supras, a good tech can actually reprogram the existing computer to get precise air/fuel at different temps, pressures, etc. Our cars, at least our computers, usually require a chip change to achieve the same results.

BTW when I was going to have my car dyno tuned, the techs weren't going to charge me for the tuning as this process consists essentially of adjusting a pot on the MAF to to modify the entire curve. When the car is closer to dialed in, I'll take it to a dyno shop though for an A/F reading throughout the powerband to ensure that there are no "lean" spots.

Obin, the meter is an AF30. It has 30 LEDs and is pretty expensive now that I checked it out ($130+). You can still have it for $50 though as I am using a different EFI gauge that also measures electronic injector duty cycle.

Erick

[This message has been edited by wolfrpi (edited 05-01-2001).]

Ehab · 05-02-2001, 06:45 AM

Obin, just use a voltmeter with your O2 sensor, as was mentioned earlier. The schematics and details are in a tech article on the pelican board (I don't know if it is still there)
The bottom line is that you want the voltage to oscillate between .2 and .8 volts continuously after it warms up. If it exceeds either limit, then you need to fiddle with the MAF to fix it.
Good luck.
E

Obin Robinson · 05-02-2001, 08:47 AM

wolfrpi.

you have mail

obin

vas deferens · 05-02-2001, 08:06 PM

kaffinekrazed
nope we have no smog certs in Hawaii. WE have though, saftey inpsections due once a year....you know....good tires, bumpers on the car, signals and washers working,......seems like baby squat to you guys but believe me, out here, there are alot of cars that don't even have headlights......hardy har har.....anyway eveyone has their own particulars in their corner of the world....vas deferens