Annoying O2 Counter box?
 

Is this my culprit?
I have the opportunity to disconnect this annoying little sucker, I just want to make sure this is my culprit, first.
My old '79 SC didn't have this box, so I'm figuring it either has something to do with the cruise control or smog stuff.
One of the leads from it goes to the OX light on the dash.
Can I just unplug this sucker?

It sits just below the tach on the drivers side of the car. This shot was taken from the trunk looking back.

http://forums.pelicanparts.com/uploa...1074181751.jpg

Yep that is the O2 sensor counter. When the O2 sensor has been in the car I think for 30K miles it will turn on the O2 sensor light. This indicates it is time to change the sensor on the exhaust. Push the reset button and your good for another 30K. What has this poor little box done to receive your wrath?

Yep, disconnect it and the clicks will stop.

Well the whole way home on a 750 mile road trip from Seattle to Montana, I thought the clicking I was hearing was everything from a bad wheel bearing, to a screw in a tire, to a thermonuclear warhead timed activated detonation switch.

It drives me nuts, bottom line.
And, I have SSI's so I have no O2 sensor.

Cool, ... it dies tonight. ...sleeps wid da fishes....

I had the exact same experience, Leland. The simplest fix is to find the brown ground wire that goes between this unit and one of the instruments, perhaps the tach. Disconnect this, and the clicking stops. Tape it up good and it won't fall against a hot wire and start a fire.

Whatever you do....don't cut the red wire.....I know, heard that one before.....

The 914s had those too, was mounted under the floor boards in line with the speedo cable. Mechanical unit. Real PITA, like the seat belt buzzer.

I don't know how valid this is, but I was just talking to a race mechanic about a 911 I am looking at buying (not yet seen), that has a 3.0L later SC motor. We talked specifically about the O2 sensor, and he said something to effect that these models had a Lambda control, which is feed info by the sensor, instead of the smog pump. About 60% (his numbers) of SCs have this wire disconnected, but you'll get better performance by tuning the car into this "lambda window." This is just heresay b/c I have no first hand experience with this, but I thought I'd pass it along, FWIW. I know my old 3.0L car did not have this control unit, but that motor was a 1978.

You can disconnect the O2 sensor with good results, but *not* the Lambda computer/frequency valve.

And the counter behind the dash is not a sensor; just a passive clock that turns on the O2 service light.

That is correct. 78-79 cars had a smog pump and no O2 sensor. 80-82 had the O2 sensor with a control box under the passenger seat. Many people advocate disconnecting the sensor from the system, and setting the mixture slightly richer than stock.

That being said, this box is not related to the lamda system. All it does is count miles. When it gets to 30,000, it turns on a light telling you that it is time to replace your O2 sensor.

You hit the reset button and it starts counting again from 0.

Tom

I believe 1980 was the first year of the Lambda control box. But then again I might be wrong!

Hey Leland,
I had that lousy sound you described also, anytime it got cold. I could not figure what it was until your post.
I just took everything apart to get to the box, could not figure where the leads went, so I cut the brown wire at the plug. I just drove the car, it's 25 degrees here, and no more noise! :D I did get a high pitch sound that was not there before, sounds like my fuel pump. Please let me know how you make out with yours.
And what you did with your wires.

George, I just unplugged the whole shebang. I too couldn't find a single brown wire connection so I just unplugged the white connector.
Hope it still runs ok.

That's what that sound is! For months I thought my speedo was on the fritz and getting ready to blow! He he he, sometimes it really helps just browsing through other people's posts even if you think it doesnt apply to you :D

Matt, after I pulled everything off I did a search on the plug. John Walker had a good short cut, just pull out the tachometer and look down obout 10" and pull the plug. My noise stoped.
Good luck.

You talking about pulling the ground wire George? Or is it some other plug?

Matt, look at Leland post that shows the unit, pull the white large plug. That is what is recommended.

Let me know if you hear a noisy fuel pump buzz after you disconect the plug, my fuel pump got a loud buzzing sound after I cut the brown wire. I think it was a coincedense but just want to make sure that it was not related to cutting the wire.

Thanks,

You guys are great. My car (1981 911SC) was in the shop less than two weeks ago and one of the items to be tackled was fix and annoying 'click', 'click', 'click' while the car was moving. I was told that it would require an overhaul of the speedometer by the garage.
I saw this post and thought it was worth a try. I went the long route and pulled the blower motor just as a precautionary measure so that I could ensure I was pulling the plug on the right unit according to Leland's photo. Then I test drove the car and for the first time since owning it there was no 'click', 'click', click'. George, no strange noises from the fuel pump were heard.

Daryl, glad to hear the Click------ went away. It was a good thing Leland bought a SC again:)

If you want to get rid of the whole shebang (for those with mechanical gauges):
Nylon stock, dimensions 3.1" by 0.7", thread pitch 1.5. Take the shaft out of the original box and drill a hole for it in the nylon cylinder.

http://forums.pelicanparts.com/uploa...1074573134.jpg

Thanks guys, I pulled the plug from the speedo hole and voila, no more clicking! Just the sweet sound of my flat six ;)