924Board.org

Kenodog · Joined: 25 Jun 2003 Posts: 2669 Location: Vancouver,B.C.

Can someone tell me what the shielding on the ox sensor wire on an 80 turbo is for and is it ok to cut it under the dash to splice in a wire for an a/f ratio gauge or do I need to run a new wire under the hood to the sensor itself?
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1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140

Smoothie · Posted: Fri Jul 08, 2005 9:47 am Post subject:

I don't know nothin' about any wire shielding. Mine only had a metal shield over the sensor itself. The wire's just regular old plastic coated wire.
A tip though: If there's a connector on the wire under the car about a foot or two from the o2 sensor, if you can, tap the gauge in somewhere between the sensor and the connector. That way you can have the o2 sensor unplugged from the lambda box and still get readings on the gauge.
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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

Kenodog · Joined: 25 Jun 2003 Posts: 2669 Location: Vancouver,B.C.

On my car it's a big fat bright green wire and if you slice alittle shielding off you see copper,but, under the copper in the center,is another green wire.

The only possible thing I can think this would be for is to shield against radio emissions from the engine ??

Crap,and after all the hard work I did just to install the gauges in the new a-pillar pod.This is some kind of sick electrical engineers joke.

geeks.
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1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140

Peter_in_AU · Joined: 29 Jul 2001 Posts: 2745 Location: Sydney, Australia

One thing to keep in mind is that the ox sensor only puts out a very small voltage (up to 0.7v) and a very small current. When you splice into the sensor wire don't cut the wire just strip back the insulation and wrap the wire for the A/F gauge around the sensor wire and solder up and insulate well.

If you accidently reduce the voltage going from the ox sensor to the computer by cutting the wire and joining it up badly your fuel mixture will get messed up.
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1979 924 (Gone to a better place)
1974 Lotus 7 S4 "Big Valve" Twin-cam (waiting)
1982 924 (As featured on Wikipedia)

Learn to love your multimeter and may the search be with you

Paul · Posted: Fri Jul 08, 2005 1:29 pm Post subject:

I believe the sheild provides a very good ground for the O2 sensor, so I always treat it like it's part of the circuit.

Smoothie · Posted: Fri Jul 08, 2005 3:54 pm Post subject:

According to the wiring diagrams for both series 1 and 2, the wire shielding doesn't extend all the way to the sensor. -And that agrees with what I have under my car - no wire shielding, just a single conductor plastic covered wire at the sensor end. It looks like the shielding is only that and doesn't actually ground the sensor. I'd run the gauge wire all the way out and tap in between the sensor and connector like I mentioned - this way it's handy to be able to disconnect the o2 sensor, but still get readings from the gauge (good for checking the basic air:fuel out of lambda closed-loop control).
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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

Mike924 · Joined: 12 Aug 2004 Posts: 2601 Location: IoW UK

Gram · Posted: Fri Jul 08, 2005 8:32 pm Post subject:

Where did you buy the A-pillar pod from..?
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'82 924 NA Euro (hers)
'98 Audi A4 TDI (ours)

924guy · Posted: Fri Jul 08, 2005 10:43 pm Post subject:

i wouldnt want to risk "corrupting" the flow of the existing wire, tap off the pull connector on the cross member under the car as suggested above. ideally , i think a second o2 sensor should be added. next time i have my exhaust off, im going to have a bung welded in just for this purpose, though id like to go with a wideband setup if i can get the cash together , much more effective tool imo...
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Eric
78 924
82 931 SE "smokey"
99' VehiCross
Y2K Honda Insight
http://www.cardomain.com/id/924Guy
Performance by Pasha

John Brown · Joined: 07 Nov 2002 Posts: 903 Location: Leesburg VA

I have installed a AF meter in the car. If I knew then what I know now, I would not do it again. Narrow band sensors are almost useless to tune.

If you look at the output of the sensor with a voltmeter you'll see it swings constantly. And so does the AF reading.
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John
80 931 - #931 44Cup
99 Escalade - tows track cars
gone but not forgotten: original 924.org car - 82