[Shotimes] HEGO sensor trouble codes

[George Fourchy]

On Thu, 27 Feb 2003 13:14:02 -0600, Dave Kegel wrote:

>I'd look elsewhere for you answer.  If they're not throwing a CE light I
>doubt they'd cause the motor to stall.  I've never heard of even known bad
>HEGOs to cause stalling.

And....On Thu, 27 Feb 2003 13:14:23 -0600, Justin Schick wrote:

>I've read elsewhere that HEGOs never really "go bad", and to refresh
>them you just have to soak the tips in carb cleaner to eat all the caked
>on carbon junk off.

Lowrider went about 225K miles on its original O2 sensors.  As they wore out, the
MPG went WAY DOWN, almost overnight, in town, when I was doing a lot of engine speed
changes as I shifted gears.  On the highway, it stayed fairly close to what it
always got, but if I started fooling with the throttle, MPG would drop there, too.  
Putting in the new ones that I got with the SHOShop Y-pipe buy fixed it
instantly.... it's up at 25 mpg again.

I never ever got a CE light for them (or anything else..it does work...it comes on
KOEO). The reason they failed and that the MPG went down was they lost their ability
to switch back and forth fast enough to notice changes in the mixture and pass them
to the PCM.    

The Tbird Turbo I had before this car was the first EFI car I'd had, and I had heard
I was to change the O2 sensor about every 75,000 miles.  I did change the first one
then, and there was no change in mileage or any other parameter.  It went the rest
of the way to 200K with the second sensor installed.  Now I don't change them, or
recommend changing them, until they start to fail, noticable by a significant drop
in MPG for no other reason.

There shouldn't ever be anything "baked on" the sensors....as long as the rest of
the SEFI system is working correctly, there shouldn't be enough extra carbon down
there to coat them with anything....also they should be hot enough to burn off
anything that might settle when they are cooler.  Every time I looked at them during
the various repairs that required removal of the Y-pipe, which required removal of
the sensors, they were clean.

George