02 sensor, ground strap, and fuel trims

[joebor1776]

Hi,
I recently installed a turbo-back exhaust system, and in doing so had to cobble together the ground strap such that the original ground strap is tied to a piece of copper wire, which is wrapped around the downpipe. I'm now seeing strange "stuck" fuel trims (like 139% on the high one, etc.) that do not change. I did a search on fuel trims and see that this can be an indicator of a bad 02 sensor. My fuel trims before the exhaust job were more around 100%. Do you think this could be caused by my jury-rigged ground wire, or more likely just a bad 02 sensor that coincidentally went out around the same time? BTW, I tried disconnecting the battery to reset the ECU, but the fuel trims are still stuck.

Thanks in advance!

 

[16gpoweredgsx]

You could have an exhaust leak before your o2 sensor causing in-accurate reading. Does your o2 still cycle at idle and while cruising?

 

[123212321]

Electronics do crazy things with shitty grounds. I would just double check it like crazy and make sure that the ground is good.

 

[joebor1776]

OK, thanks, that's what I figured--I will double check the ground. Just wanted to make sure I wasn't missing something. Thanks!

 

[luv2rallye]

Exhaust and downpipes are poorly grounded. Connect the signal ground to the engine or a wire you know goes to ground.

 

[joebor1776]

Thanks. I'm not sure what you mean. This is the front 02 sensor on a 1G, and the ground strap is just a steel mesh wire attached to the frame and then attached to the down pipe (I presume it's grounding the 02 sensor because the 02 sensor housing is connected directly to the downpipe?). How would I connect it as you are saying? Thanks!

 

[luv2rallye]

The O2 sensor housing is NOT GROUND! Use must use the wires. See
http://www.dsmtuners.com/forums/bolt-tech/171244-o2-sensor-wiring.html#post1431571
and
http://www.dsmtuners.com/forums/articles-electrical-wiring/244376-oxygen-sensor-wiring.html

 

[joebor1776]

Thanks! I had seen the one thread about which wires are which, but I figured that when I removed my stock exhaust (and accidentally pulled off the ground strap), that I just needed to bolt it back into the frame. But it sounds like the place it was originally bolted to was a connection to a ground wire to the 02 sensor itself. So I must have picked the wrong bolt hole when I reconnected it. I think I'm just going to replace the sensor anyway, so when I do I'll make sure its ground is going to the frame and not the exhaust. Thanks for your help.