O2 sensor?/84 Carrera

[wolf76]

Hello. I was wondering if someone could tell me the location of the O2 sensor plug in the engine compartment. Is is on the same bracket as the cylinder head temp sensor?



Thanks,

Chris

[cgarr]

It should be clipped to the engine comp frame just below the fuel filter and its an inline plug, at least that's where it is on my 86

[wolf76]

Thanks Craig. I hope that's where it is on mine as well.



Chris

[efhughes3]

It will be. Be very gentle. There is a very good chance the plug will disintegrate due to age.

[shnewberry]

You can see the O2 sensor shield on the exhaust on my '84 engine.
Good luck.
Seth

[Hendog]

Here it is on an '87. EDIT: That's the CHT sensor plug!!!

[efhughes3]

That isn't an O2 sensor plug-in Henri.

[Hendog]

Originally Posted by efhughes3

That isn't an O2 sensor plug-in Henri.

Isn't it?

I pull that plug and measure my O2 sensor output at that point. Isn't that what he's looking for?

[efhughes3]

His O2 sensor will plug into a socket under the fuel filter on the LH frame rail.

[Hendog]

Originally Posted by efhughes3

His O2 sensor will plug into a socket under the fuel filter on the LH frame rail.

OOPS! You're right. I hate giving bad information. My pic shows the CHT sensor plug. I'll go edit that. In the meantime, here's a pic of the O2 sensor plug in the engine compartment (on an '87). I did change my O2 sensor less than 2 yrs ago; you'd think I'd remember that plug

Here ya go.

[rusnak]

I remember when I was confused about the O2 Sensor.

My 911 was failing smog, and I had to dive in and learn the system, then try to troubleshoot the problem.

The worst part was that the O2 Sensor plug was broken by the shop that was supposed to fix my 911.

Here's a pic of the two circuits for the 3.2 911 O2 Sensor. The plugs are located where Ed says, on the left hand side below the fuel filter.

I was able to glue the plug back together. Now I hold the O2 Sensor onto the plug with a zip tie around the rubber boot. I cut the rubber boot lengthwise to make it easier to remove next time without breaking the yellow plastic plug.

[wolf76]

Thanks everyone for the replies. With the help of the pictures I have located the plug in the engine bay. I am looking to disconnect it to see if it solves a flat spot issue I have. If the plug dissolves when I check it do I need to replace it or can I run the car without an O2 sensor and avoid damaging anything?


Thanks,

Chris

[efhughes3]

You can run it without it, but I'd plan on fixing it. Your car will not run optimally, except at WOT without an O2 sensor in place. I made a plug-in connector with new male and female individual wire connectors as mine evaporated beyond repair.

[wolf76]

Thanks Ed. Will do. Is there a difference between the stock Bosch unit and the after market one (bot hare sold by our host) ?


Chris

[rusnak]

Chris, if you buy a Bosch O2 3-wire sensor, then it's a sure thing. You won't have any problems.

But, I would not suspect the O2 sensor in flat spot or throttle response problem. When you disconnect the O2 sensor (the sensor circuit, not the heater circuit), the voltage to the dme from the O2 sensor will be cut off. This will cause the system to run in "open loop", or in other words, the dme computer will go into a safety mode of pre-determined ignition advance and fuel injector timing, based on temperature and throttle position. This will not fix your problem unless your dme chip image for closed loop running is damaged (not likely).

I would suspect fuel delivery pressure, or maybe a plugged cat or a muffler baffle that has come loose and is blocking the exhaust gas outlet.

Here's what I would do. Warm the car, then open the oil fill cap. The engine should stumble, then recover. Replace the cap, then disconnect the small vacuum line to the fuel pressure regulator. Should stumble then recover. The second test is the rich stop test. If there is no change in idle, then I would connect a fuel pressure gauge and test the pressure both running, and with the dme socket jumpered (engine not running). The do a fuel delivery test (volume of gas over pre-determined amount of time). All of this is covered in the Bentley manual.

If these tests show no problem, then I'd remove the cat and shine a strong flashlight in there. You should see faint light. If the tests show low pressure, then you can try running some Techron or some BG 44K in the gas tank with fresh clean Premium gas. Or you might have to replace the fuel pump, depending on how bad the pressure is or how bad the engine stumbles.