I did my longtubes over a year ago and due to an issue with the wiring for my O2 melting on the header while waiting for an extension, have been running with no O2's ever since.

I finally got around to buying and wiring in new Bosch O2's today, and my car has been running bad ever since. The idle is really rough and almost sounds like I'm running an aggressive cam. Also, whenever I slow down and put the car in neutral, the engine drops to around 300-400 RPMs and slowly makes its way back to 800 while puffing out black smoke. Taking off in the car is also horrible, with first gear stuttering the whole way through unless I have it floored.

I was wondering if there was any possibility that since the car hasn't had O2's for over a year now (although it wasn't driven for 8 months of it while I was deployed) it is just taking a while for the car to get used to having O2's and is making adjustments for them, or did I just wire them up completely wrong (they are wired directly since the connector on one of them had melted off, I went by the wiring diagram from ALLDATA)?

I cleared all my DTCs before installing the sensors, and these are the ones that came back:

P0135
P0141
P0155
P0161

All of these codes are for the O2 heaters as far as I know.

The car is a 2004 coupe by the way. Any help would be appreciated.

 

Sounds as though you may have the 02's criss crossed.
Switch them & see if that may be the issue.

 

Criss-crossed as in left O2 in right bank and right O2 in left bank?

 

JB,

I am a Product Specialist with Walker Products, a manufacturer and worldwide distributor of oxygen sensors. I believe that bumble is referring to having the front and back sensors switched, as the front two are the same part.

It sounds to me that your engine is running very rich. As you said, you may have wired the sensors incorrectly. Where did you put your upstream sensor bungs at? If they are too far down from the exhaust ports, your sensors may be getting a lean reading, causing your injector to add too much fuel. I would also check for an air leak in your exhaust system, perhaps around your header gaskets, though you probably would have noticed this before installing the O2's.

 

Yes.
Happens quite often.

 

I am definitely running rich, I can tell just from smelling the exhaust. I know that the O2s are hooked to the front sensors because the wiring coming from the motor side has male connectors for the front and female for the rears.

The bungs for the O2s were there from the factory, they are right after the collectors. The headers are TSP longtubes if that helps.

The only wiring that I think I could have messed up is the heater wires, the Bosch O2s said that the heater wires were interchangeable but the wiring diagrams said that one wire was heater low and heater high side.

I didn't think to check for exhaust leaks I'll take a look after I get off work today but I have never noticed any leaks at all.

 

As Bumble-z said, try switching the 02 sensor sides before you do anything else. They are counter intuitive in the way they go together. The one that has the wire running down the side of the bank two pipe actually gets plugged into the bank 1 pipe and vice-versa. Switch them, clear your codes and see if the issue returns.

 

I'll try that today as soon as I get off work

 

Just for clarification... I'm talking about the REAR O2 sensors.

 

One final piece that I need to share J_B. In checking with our engineering team, your 2004 Corvette is equipped with an ECU programmed for Oxygen sensor heater current monitoring (RCOHT). RCOHT stands for Resistance Calculated Oxygen Sensor Heater Temperature. If the heater inrush & stabilized current does not match what is programmed into the ECU, it will set heater codes. Your vehicle probably was equipped originally with a 5.1 ohm Heated Isolated Ground Sensor. If you used a "UNIVERSAL" Sensor with different heater and grounding characteristics, this also could be part of your problem.

 

I have no rear O2s so I'm not worried about the rears.

 

I'm going to take my car to a buddy of mine with EFI Live and scan the car see what the O2s and heaters are doing. Thanks to you and everyone else for the help

 

Just so it is clear. The front O2 sensors connect to the plug on the same side as the header installs to. Passenger header, passenger O2 sensor and passenger side plug for the O2 sensor. Same on drivers side.

On some headers the front O2's install so the wiring end points to the opposite side and then the person connecting them runs the wiring up the opposite side of the car and connects to the harness on the opposite side, swapping the O2 sensors and it doesn't run right.

 

Ok thanks for the clarification, I have them connected to the right plugs then.

I just got done scanning the car, 25% fuel trim and the O2s are showing 0 mv so I apparently wired something wrong, is there any way someone could post up a schematic for the O2 wiring in case the one I got from alldata was wrong please?

Also, I got the rear O2s turned off, which seemed to help a little bit but not much.

 

My general observation has been that there are 2 of the same color wire for the heater and then the lighter of the 2 remaining wire colors is the sensor negative and the darker of the 2 remaining colors is the sensor positive. It seems to me the wire colors on the sensors can vary depending on the sensor make and the year it's made for.

I don't know the wiring on the car side.

 

It sure sounds like your sensors are crossed.

 

In case anyone cares, I had the wrong wiring diagram. Thanks for the help

 

Took a while, but good to hear.