mochamedics

question for testing purpose how do you delete 02 sensor ?i think i read you disconnect it and ground it is this correct the wire to the computer.

Jon F

Just undo the sensor plug. Don't ground either end of the disconnected wire.

tuk_928

This worked fine for my 87 535is since it runs so lean anyway...but what about 928s?

PorKen

If you ground the oxygen sensor wire to the ECU, it will richen the mix.

Works as a band-aid fix for a big bore exhaust if you don't have an adjustable FPR (and don't care about gas mileage).

tuk_928

Ken...

What do you mean...."...DON'T CARE ABOUT GAS MILEAGE in a SHARK???? With TODAY'S FUEL PRICES" ???

Currently my Shark and 535is (unplugged O2 sensor...until I can get a new Bosch "Ford Mustang" sensor...$45 vs. $150 ) get the same gas mileage...

Best,
Tim

Thom1

Tim,

Is there O2 sensor interchangeability from Mustang to 928?

ViribusUnits

There are universale sensors. They're all the same, excepting the connecter to the computer.

So you simple cut the old sensor off, and splice the new one to the old connecter. They're like half the price.

Thom1

Specifically anyone?

ViribusUnits

Go to your local auto parts store and ask for a "Universal 3 wire O2 sensor."

IIRC, the part number is 13913 by Bosch. It's about 50 bucks.

All just about all of the O2 narrow band sensors work the same.

splice the wires into the old connecters, and your good to go.

Thom1

Thanks,... now how do ya' know when it is bad?

ViribusUnits

Get the car good and warmed up. You will need two people for this.

Pull the lead to the sensor, if it returns 0V, then it's probably bad. Get a propane torch, and blow propane into the engine. The sensor should rapidly start returning 1.2V or better. Nearly instantly. Be careful!

Next, go up to the brake booster, and have someone pull the hose for it. The O2 sensor should rapidly fall to 0 V.

If it's slow falling, or doesn't do eighter of the above, it's shot.

tuk_928

Thom1,
Sorry...hadn't checked-in 'til late tonight...see what ViribusUnits said. He knows more than I do with respect to the interchangeability of O2 sensors for the 928. I was speaking from my BMW side of the brain. Thanks VBU...
Best,
Tim

Thom1

Thanks again.

Does the car put out black smoke, run rough or something to point to a bad sensor?

2V4V

Thom,

Car _might_ run slightly 'off', have less than stellar gas mileage, idle poorly, but most obviously will have higher emissions, esp. if your state/locale does the dreaded 'chassis dyno rolling road' wherein some goober gets in your car and plays with the loud pedal as a computer indicates. (As you may surmise, we have to do that where I live.)

Results of a failed/failing sensor vary by car, but for $50, I would replace it if I was not absolutely sure of it's age/condition.

VU is partially correct, 90+% of all O2 sensors work the same.

There are 2 notable exceptions in some (not all, IIRC) Chrysler products (they output differently than all other narrow-band O2 sensors) and the wide-band O2 sensor- which generally has 5 wires and is only found on 1 older Honda Civic lean-burn motor, a coupla newish VW products and in test equipment like WBO2 meters. For the moment anyway. Look for more of the WB stuff to hit the aftermarket as the price continues to drop - it actually allows you to run very accurate mixtures other than 14.7:1 in a closed loop fashion - this is most useful, esp. on a force-inducted scenario.

While we're on the techie side of things, a narrow-band O2 sensor is really just a stoich indicator. It is reliably accurate ONLY in around (varies a bit) the 14:1 to 15:1 fuel/air mix range. It is most accurate at (surprise) 14.7:1 (lambda).

Once you leave it's very narrow band of design, the outputs are completely non-linear, and in fact, are often damn-near random.

Disconnecting your O2 sensor is a guarantee of unpredictable and unreliable results, which will, at best, be bad.

HTH,

Greg

Aguila

VU:

Can you point me to some pictorial illustrations on doing the test? blowing propane to engine with a blow torch conjures up image of fire destruction to my shark...

Thanks