did a near complete tune up to get rid of a running rich prob(stalling and not even drivable)....with an o2, and a thermo sensor, tps and didn't help, then i finnally made the code checker and Im getting code 05 for o2 sensor....but its only comming up when the car is running, not with the key just forward. Thanks for anything....Im going to look at grounds.....especailly on the muffler

 

Yeah, if it was only the o2, you wouldn't having all thoughs problems. They've been ripped out all together and the car drives fine. Rember that the stock ECU is "dumb" & won't necessarily give you any info regarding the real problem. Trouble shooting is the best way.

 

You do want it working.
If not, the default mode wastes fuel.

The wire to the sensor has a co-axial shield that is grounded.
It's easy to short the signal wire to that shield when splicing in a new sensor.

 

Most likely the wiring harness is broken internally.
It's most likely broken somewhere in the engine bay, as the heat wreaks havoc on the wiring, and the O2 sensor wiring runs over the hot exhaust manifold (turbo?).

The O2 sensor is only used above about 2,000RPM and under very low load conditions (as signaled but the boost or pressure sensor).
It is not used during idle or higher engine loads, this is why you don't see the light trigger until after you're driving around a bit.

A bad or malfunctioning O2 sensor can decrease gas mileage up to 20% to 25%.
If you want your gas mileage back, I'd recommend to fix the problem.


-Ted

 

I am with Ted, on my 88 vert, it looks like the last owner replaced the entire wire from the ecu and now it is shorter than stock setup, a bear to unhook the connector.

ted, is it ok to solder some wire and extend the wire from the ecu? or should I just run a new wire altogether?
if a new wire, what guage? color (trying to keep sanity for next owner) should I use?