Where does it plug in?

[bakerlaw67]

I'm beginning to wish I had my '65 Skylark back! I got my car back after a cheap engine rebuild (I have abandoned my previous plans and am focusing on having a decent-looking, well-running, stock-performing car). When I picked it up, the mechanic suggested a carb rebuild as it seemed to be running rich. In fact, sometimes when I shut the car off, there is a loud bang out the pipe on the side without a muffler (don't ask).

Anyway, I was poking around under the hood and I noticed a sensor on the up pipe (?) that was not plugged into anything. It isn't long enough to go very far, yet I can't seem to find where it goes. Of course, my '83 Chassis Service Manual is out being scanned to be put on CD, (not even sure if it would help since this would be the first time I would have opened it). I was already working on getting a used replacement carb to have rebuilt so that my downtime is limited, but I don't remember this problem before taking it in, and tend to associate the rich mix to the disconnected sensor. Please help (before I get parenthetical again).

Also, does anybody have a part number for the spring-loaded bolts that hold the downpipe to the housing. One seems to have fallen out and the exhaust leakage gives me a headache for my daily commute to/from work. Or maybe its the car and the little "quirks" that do it!

The thing that makes me so mad is that I love the way this car feels when I push the skinny pedal, even with the exhaust leak, rich a/f mix, lack of muffler on one side, and bald right rear tire!

 

[pat83t]

That sounds like the oxygen sensor. Should be a single wire pig-tail that goes to it. It is dark otherwise I would go out and see where it goes to so you could retrace it. That or take a digital pic and send it to you. let me know if you don't find where it goes.

 

[b4black]

Also, does anybody have a part number for the spring-loaded bolts that hold the downpipe to the housing.

BOLT Group 3.613, # 1256567
SPRING GROUP 3.613, # 587575

These are common exhaust parts, so you might be able to find them in a local parts store, naybe in the Motormite HELP section.

 

[bakerlaw67]

Thanks guys.

It IS a single black wire. A picture would be awesome, but if I knew where to look, (firewall, fender, carb, etc) it would be a start.

 

[b4black]

Look along the right side fender for a purple wire coming from the ECM. It should be near the MAP sensor or under the coolant recovery bottle.

Think twice about going back to a mechanic that recommends a carb rebuild before checking the condition of the O2 sensor. Missing the fact that's it's not even connected is amazing.

The disconnected sensor should have turned the Check Engine light on. I suspect the sensor has gone bad, and instead of fixing it, it was disconnected and the Check Engine light bulb was removed (or eventually burned out). Hopefully this is all it is.

I highly recommend getting a OTC Monitor 85 or 2000 (or similar) from ebay. It would have diagnosised this problem immediately. If you like the way it runs now, you be even happier when it's running right.

 

[turbofish38]

Part number 1256567 is now discontinued from GM. I've seen these bolts on the HELP rack at AutoZone. There are 2 or 3 different bolts that look alike, just make sure you use the correct length of springs with them. The early oxygen sensors used a black wire instead of purple. GM changed the color more than 10 years ago so it might be time to put a fresh one in.

 

[bakerlaw67]

I was NOT going back to this mechanic under any circumstances. Live and learn I guess. The Check Engine light does come on, but not until the car runs 10-15 mins. Thanks for all your help, but particularly, thanks for not making me feel like a moron (even though I'm sure its what you are thinking!)

 

[pat83t]

Never crossed my mind for a minute. Again it is dark but I will see what I can do tomorrow on that pic. As for the bolts and springs, now that they have mentioned it HELP! section of motormite does have them. If you are in Arizona check your local Checker/Schucks/Kragen. They don't stock it around zip code 85233 but they can order it. The motormite part # should be 03091. Sorry I was bored so I did alittle research. Apparently I never leave work even when I am home.

 

[bakerlaw67]

I FOUND IT!

I just started tracing wires on the right side from the firewall out and found the end stuffed under/around the battery.

I drove around for more than an hour and got no "Check Engine" light, and the car *SEEMED* to run better. There was definitely no bog when I went to WOT anymore.

I went to AutoZone, but they were closed. There is a 'Zone and a Checker Auto near work. I'll look for the bolts tomorrow. Thanks again.

I've got to get this car out of daily service so I quit this "keep it running" crap!

 

[pat83t]

Good job, glad to hear that it is running better. Still need the pic?

 

[b4black]

Originally posted by bakerlaw67
The Check Engine light does come on, but not until the car runs 10-15 mins.

Soemthing else seems odd here. With the sensor disconnected, I think it should throw the Check Engine light on as soon as it went into closed loop. My car goes into closed loop within a minute of start up. Maybe your staying in open loop to long? (This is were a shop manual would help you out. It explains in detail about how the ECM works). Closed loop in the normal operation where the fuel mixture is controlled via feedback from the oxygen sensor. Anybody know an easy way to confirm closed loop without a scan tool?

Since you seem to have a functional ECM, I would recommend pulling the stored codes (and write them down). Then disconnect the battery to clear them. Next time the light comes on, it will only have the new code stored.

Read this page on the Check Engine light written for the 86/87 engine:
http://www.gnttype.org/maint/malf.html

This page has the '83 codes:
http://home.flash.net/~rjgeorge/ecm.htm

 

[Peter]

Originally posted by bakerlaw67
When I picked it up, the mechanic suggested a carb rebuild as it seemed to be running rich. In fact, sometimes when I shut the car off, there is a loud bang out the pipe on the side without a muffler (don't ask).

even with the exhaust leak, rich a/f mix, lack of muffler on one side,

Any car that has exhaust leaks is liable to backfire, caused by the mixture [possibly over rich] igniting in the exhust system. The absence of a muffler will also not help this.

Check this before carb. rebuilding. Forget this mechanic.