924Board.org

[rcoble]

I have a 78 924 and would like to install an <air/fuel ratio gauge> to keep track of when the car is running rich or lean. These are connected to the oxygen sensor, which I don't have on this early model 924. Question is, can I just install an oxygen sensor into the exhaust just to use with the gauge? Or will the sensor require some sort of power/electronics to get a signal out of it? I'm just tired of running around under the hood and would rather have the info all in one place, ie a fuel pressure gauge, vaccum, sensor indicators etc. Just seems like an easier way to trouble shoot the dang thing. Or it could be my computer engineering background made me an information addict.
Thanks
Robert
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78-924 red , my first real car at age 44.
80-928 black, bought from turbo924.
83-928 black, My current effort.

[Raceboy]

no problem there, you should prefer sensors with 4 wires (heating, more accurate reading) or 5 wire (Wideband). You can use regualr voltmeter too as a gauge, but if you have A/F meter, there's no problem.
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'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

[Smoothie]

My car already had an o2 sensor, so I just had to tap into the wire from it to feed the signal to the air:fuel gauge. If you have to add one, you can get a fitting called a "bung" , drill a hole in the exhaust somewhere within the first couple of feet after the exhaust manifold and weld the bung in. If you have to put it further away, you might have to go for a heated sensor, but if you're not too fussy, a single wire sensor mounted close'll work fine - that's what I have. No special electronics required - just provide 12V+ and ground to the gauge plus the signal feed directly from the sensor.
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"..it's made in Germany. You know the Germans always make good stuff."


'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

[rcoble]

Thanks, that sounds easy, I cand weld no prob. What would the other wires be for on a four or five wire sensor? and any recomended sensor that might be economical and easy to get the bung for?
Robert
_________________
78-924 red , my first real car at age 44.
80-928 black, bought from turbo924.
83-928 black, My current effort.

[Smoothie]

I use the single wire universal Bosch sensor. The last one I bought was from thepartsbin.com at approx $19. JCWhitney should have them too. They should all be the same thread size and whether heated or not, the signal output is the same (the sensors respond the same and return the same signal voltage whether heated or not)(the only differences between the Bosch Universal and the 924 specific Bosch version are one is ~$19 and has to be spliced into the connector from the old sensor, while the other goes for something like $60-$70 and comes with the correct connector already attached.)
As far as I know, a wide band sensor can only be used with a wide band gauge or display.
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"..it's made in Germany. You know the Germans always make good stuff."


'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

[rcoble]

Where is the oxygen sensor usually mounted on 924 cars that have them. The pict in Haynes is not too clear. Or, where would you drill the hole if you had the choice, as I am about to pull out the tools.
_________________
78-924 red , my first real car at age 44.
80-928 black, bought from turbo924.
83-928 black, My current effort.

[Lizard]

small H pipe between the 2 runners on the factory down pipe
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3 928s,

[speedsta2003]

if you want a light show than you can use your stock 02 sensor. But if you want an accurate reading to really know if youre running rich or lean then youll need a wideband 02 sensor. A wideband 02 will only run you around 50, plus however much a gauge is.
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My Old Porsche Thats Sold
http://members.cardomain.com/jatbballboy15

[rcoble]

Ok Fuel Pressure gauge and Air Fuel Ratio Gauge going in, but will have to wait till Tuesday, I have a four day race starting Thurs. (bicycle)
_________________
78-924 red , my first real car at age 44.
80-928 black, bought from turbo924.
83-928 black, My current effort.

[dpw928]

Why the fuel pressure gauge? Your CIS system actually has three pressures. Pump pressure, system pressure and control pressure. To monitor one pressure won't tell you much.

Dennis
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

[rcoble]

I just had that gauge with the air/fuel gauge so what the heck. It's a nice remote sensor type (no fuel line in the cabin) .
_________________
78-924 red , my first real car at age 44.
80-928 black, bought from turbo924.
83-928 black, My current effort.

[dpw928]

If you install the sensor between the fuel filter and distributor you can measure your pump pressure and detect if the filter is plugging or the pump is going bad.

Dennis
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

[rcoble]

I'm on the road now but I seem to remeber in the Haynes book they have you hook up a fuel pressure gauge between the fuel dist. and the controll pressure regulator? I think that was part of how you adjusted all of the fule mix/supply. I'm probably wrong, I just read the book once, and haven't started finding all these parts in real life yet. But, if this is as I remeber would'nt it make sense for me to install the gauge/sensor in this position?
_________________
78-924 red , my first real car at age 44.
80-928 black, bought from turbo924.
83-928 black, My current effort.

[Smoothie]

Well, that would give you a reading of control pressure which is good to know, but for a dash gauge and if you have to pick one place to read from, I'd think some place that gives you system pressure (aka primary pressure) would be more useful.
Then again, if you can't decide, get a second sender, wire the two senders through a switch then on to the gauge so you can flip the switch and view the reading from sender A or sender B as you choose.

Fuel pressure readings actually aren't used to set air:fuel mix, but they will help you troubleshoot and find faulty components that can in turn screw up the air:fuel.
_________________
"..it's made in Germany. You know the Germans always make good stuff."


'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

[rcoble]

Thanks, thats a great suggestion. I'll have to re-read that section on the CIS system when I get back.
I'm mixed up on the "Control pressure regulator" and the System Pressure Regulator"
_________________
78-924 red , my first real car at age 44.
80-928 black, bought from turbo924.
83-928 black, My current effort.