So my 1986 Camaro IROC Z with 305 TPI has this problem where when it starts up, me engine sometimes "surges" it will rev all the way to 1500 rpm and down to 400 rpm and almost stalls. It does this for a good 15 seconds until it levels out. It also has slight hesitation. Many suggested the fuel filter and the fuel filter no doubt needed replacing, so much dirt and crap came out of the stock on. Replacing that fixed my stalling when braking or simply letting my foot off the throttle issue but not the surge issue. Doing research on other Chevy forums for the C1500s, Blazers, Tahoes, etc. Many reported the surging issuing as being a bad 02 Sensor issue. Fair enough.

Problem is, I can't find mine. Other threads on here insist that it is on the driver's side manifold collector. Well about 6 years ago, I had a shop replace my old rusty/leaking exhaust with a full Hooker set up (Shorty Headers, Y-pipe and muffler). Could they have deleted the 02 sensor?
Threads keep saying trace the purple wire by the driver's side firewall to the 02 sensor but I can't find a purple wire. Much less any wire on either side of the fire wall that's running to the exhaust. I'll crawl under the car again. Maybe I'm just missing it.

 

The original location is indeed on the driver side exhaust manifold.
If the sensor was there, I'm sure you would see it...

 

Not without a COMPLETE retune.

The O2 sensor tells the ECM how its present fuel metering is working so that it knows whether to increase or decrease the amount that it feeds. Without it, the ECM is "blind".

Leaving it out will set a code, as will connecting it but leaving it hanging in free air, because the ECM will either not see it at all, or will not be able to vary its indication by its action. It can be "eliminated" by using a pure S/D tune, much as an older carb didn't require it to work; but that would require extensive dyno time etc., to program in every possible scenario the remaining sensors (TPS, MAP, etc.) would present to the ECM.

You no doubt still have one. Just follow the exhaust system, it'll be there somewhere. My guess would be the driver's side collector, as far forward as possible after the 4 primary tubes meet.

 

I don't know if I am blind as hell, but I cannot find this 02 Sensor for the life of me! I've checked all up and down my exhaust and nothing! On the driver's side header there is a port for it but it's sealed with a bolt. I can't find a wire anywhere. I've check the passenger side, further back along the straight pipe, up front, etc. No 02 sensor anywhere!
Does anyone have a picture of the wire and where it runs to underneath the hood? Maybe I could trace it? Or does anyone with a full hooker exhaust system have a picture of where it is?



Looks like a port for the 02 sensor but it's not there!

 

This is where it goes...

 

I get that but I have headers. As you can see from my pictures my header just has a bolt plugging it up. Where does the wire lead to on the firewall of the engine? Where does it run to?

 

I found this under the engine. It has a purple wire and it runs to the Fuel Pump/MAF/MAF Burnoff relays. Nothing is plugged into it. But the pig tail from my new 02 sensor fits it perfectly! Could this be where my 02 Sensor belongs? Could the old shop have deleted it and some how my car ran normally for 5 years and only now it's running poorly (rotten egg smell, surging idle, low power)?
Or perhaps I still have a bad 02 sensor in another location (not sure where) would it be safe it plug my new 02 sensor into this pigtail and screw it into the port on the driver's side header?

What does that long pigtail go to?

The wire itself runs to the Fuel Pump/MAF/MAF burnoff relays.

Is this for the 02 sensor?

 

Is the wire purple? Might want to run a afs74 acdelco

 

It looks purple but where is the 02 Wire suppose to lead to under the engine? Does it go to the Fuel Pump/MAF/Burn off relays? I don't know if that's the correct wire or not.

 

It goes back to the ecm through the passenger side pass through connectors and ends up where you pictured next to master cylinder.

 

The wire for the O2 sensor would come from the passenger side fender apron, not the firewall. It is part of the ECM wire harness...

 

Do you have a picture of what it looks like? I can't find anything. The manual is no help either.

 

Do you have a picture of what it looks like and where it comes out from?

 

D7 of ecm, ground and ohm then disconnect from
ground and will see a open circuit. I’m sure you have it pictured.

 

I think it's it. I traced that pigtail with the purple wire a little more and it runs into this collection of wires that goes over the brake booster and under the distributor. I'm assuming it mixies in with the wires on the passenger side. If that is the pigtail connector and I can't find my 02 Sensor (i'm not sure if the car has one) would it be safe to install a new 02 sensor into the header bung and plug it in? Even if my car may have another 02 sensor somewhere?



This runs above the brake booster and under the distributor to the passenger side.


The purple wire with the pigtail leads to this.

 

Hey could anyone confirm if that purple wire and pigtail is the correct 02 Sensor pigtail or at least could someone take a picture of where the pig tail connects too?

Also if that is the correct pigtail would it be safe to plug in the 02 sensor, install it in the driver's header, even if I possible have another bad one somewhere?

 

I don't know what color it's supposed to be. The pigtail on my O2 sensor is black, but it is no longer being used.
One end of the wire you're looking for connects to the ECM and the other end to the O2 sensor...

 

What does the wire that connects to the 02 Sensor look like?

Is it possible that when my Hooker Exhaust system was installed 6 years ago, they deleted my 02 Sensor? Why is yours no longer being used?

 

It looks like a wire, about 18 gauge. As I said earlier, I don't know what color it is supposed to be, but the factory service manual may have that information.
Mine is no longer used because I deleted the ECM...

 

That's the problem, the factory manual shows a purple wire, I found a purple wire above that I posted in my pic, but I'm not sure if that's it or not (especially that it's pretty foward near the driver's side fender as where the manual has it more along the firewall) but it doesn't really show me where it's suppose to be or what the pigtail actually looks like. I'm really baffled as to where my 02 sensor could be or why it would be deleted. That's why I'm hoping I can see a picture of the pigtail it connects to and where that actually leads to. If I can find that, I can get this car fixed. I'm hoping someone can just show me a picture of their pigtail and wire.

 

Can anyone please show me a picture of their 02 Sensor pigtail and where it runs to in the engine? That would help a lot.

 

I am beyond baffled at this point. So I decided to to try and install my O2 sensor using that pigtail pictured above and the one I brought from the auto parts store. I removed that bolt that was in the exhaust bung and attempted to install the 02 sensor but it couldn't fit. There is a big chunk of metal behind where I removed the bolt. Like it's blocked by metal wall. The hole is filled in and nothing could get in. I assuming the bung is suppose to be hallow for the 02 sensor to read the flowing exhaust. As to why it's blocked I'm baffled. I've checked everywhere else on the exhaust and cannot find anything that resembles an 02 sensor or wires. I checked the straight pipe (since I know some cars have it by the cat but nothing).

The only thing that resembles a place is that bung by the driver's side and that pigtail on the driver's side. Now the mystery is how was my 02 sensor deleted and why having missing 02 sensor issues only started in the last month?

Here are pics for details. If anyone has another idea of where it could be. Please let me know. Or if you can post a picture of your pigtail and the wire, please do.



My only other theory. Could this bolt have snapped when I tried to take it out?

 

The only way you're going to find the wire is to open up the ECM wire harness shrouding/split tubing and trace it. That harness comes from the PASSENGER-SIDE fender well through an opening in the PASSENGER-SIDE fender apron near your A/C evaporator & blower motor. The O2 sensor is obviously missing which is probably why the car runs terrible, unless a previous owner converted the car to run without the ECM, which means a vacuum advance distributor and non-CCC carb...

 

I've owned this car for 9 years. I had the exhaust replaced 6 years ago. Wouldn't I have noticed bad the car running terrible by now? Why has it only shown this symptoms in the last month? That's what baffles me the most. It's been daily driving for 9 years. If it was driving without an 02 sensor, wouldn't the motor be shot by now?

I see a purple wire that runs into that tubing and comes out the driver's side near the brake booster, that I posted above. It's the only purple wire with a pigtail. If someone can just confirm that is the correct pigtail that would help a lot.

 

Yeah, if that were the problem, your car would have been running badly 6 years ago. Not sure what you have going on there, but I understand your frustration.

I think you're confusing the word "pigtail" with connector. The purple wire you are talking about has a connector on the end of it.
A "pigtail" is just a short wire or cable attached to a component (like the O2 sensor). Since your sensor is obviously not there, there is no "pigtail" for the O2 wire to plug into...