Cal

I've seen lots of posts lately concerning the O2 sensor. Is there a way to
check them? I don't have any error codes, but I think that the downstream
sensor close to the cat converter is not working. I have a '97 GC. thanks!

TJim

Why do you think that?

--
Jim
98 TJ SE
90 SJ GW
http://www.delawareja.com/gallery/JDJeep98


"Cal" <codom1@triad.rr.com> wrote in message
news:CYVeb.17738$xB4.13406@twister.southeast.rr.co m...
> I've seen lots of posts lately concerning the O2 sensor. Is there a way
to
> check them? I don't have any error codes, but I think that the downstream
> sensor close to the cat converter is not working. I have a '97 GC.
thanks!
>
>

TJim

Why do you think that?

--
Jim
98 TJ SE
90 SJ GW
http://www.delawareja.com/gallery/JDJeep98


"Cal" <codom1@triad.rr.com> wrote in message
news:CYVeb.17738$xB4.13406@twister.southeast.rr.co m...
> I've seen lots of posts lately concerning the O2 sensor. Is there a way
to
> check them? I don't have any error codes, but I think that the downstream
> sensor close to the cat converter is not working. I have a '97 GC.
thanks!
>
>

Cal

Even after a 50 mile or more warm up period, my 'catalyst' monitor is never
ready with a scan tool. I would like to be able to test the O2 sensor
downstream from the converter to see if it is bad. I think this may have
been a problem for a while. It may be related to a carbon problem I seem to
have on occasion. My dealership has had this jeep for up to 2 days (when it
starts to misfire) and they have never been able to correct it. A bottle of
good fuel injector cleaner always 'fixes' it though. I have had thin, hard
carbon deposits on several plugs in the past, and suspect that incorrect
data from O2 sensors and rich fuel is probably to blame. I know there have
been lots of comments about 'ordinary people' having scan tools on this
site, but, apparently, some dealerships don't need them either.
"TJim" <jim@ranlet.nospam.com> wrote in message
news:MDOdnVZF6I8gseGiU-KYgg@comcast.com...
> Why do you think that?
>
> --
> Jim
> 98 TJ SE
> 90 SJ GW
> http://www.delawareja.com/gallery/JDJeep98
>
>
> "Cal" <codom1@triad.rr.com> wrote in message
> news:CYVeb.17738$xB4.13406@twister.southeast.rr.co m...
> > I've seen lots of posts lately concerning the O2 sensor. Is there a way
> to
> > check them? I don't have any error codes, but I think that the
downstream
> > sensor close to the cat converter is not working. I have a '97 GC.
> thanks!
> >
> >
>
>

Cal

Even after a 50 mile or more warm up period, my 'catalyst' monitor is never
ready with a scan tool. I would like to be able to test the O2 sensor
downstream from the converter to see if it is bad. I think this may have
been a problem for a while. It may be related to a carbon problem I seem to
have on occasion. My dealership has had this jeep for up to 2 days (when it
starts to misfire) and they have never been able to correct it. A bottle of
good fuel injector cleaner always 'fixes' it though. I have had thin, hard
carbon deposits on several plugs in the past, and suspect that incorrect
data from O2 sensors and rich fuel is probably to blame. I know there have
been lots of comments about 'ordinary people' having scan tools on this
site, but, apparently, some dealerships don't need them either.
"TJim" <jim@ranlet.nospam.com> wrote in message
news:MDOdnVZF6I8gseGiU-KYgg@comcast.com...
> Why do you think that?
>
> --
> Jim
> 98 TJ SE
> 90 SJ GW
> http://www.delawareja.com/gallery/JDJeep98
>
>
> "Cal" <codom1@triad.rr.com> wrote in message
> news:CYVeb.17738$xB4.13406@twister.southeast.rr.co m...
> > I've seen lots of posts lately concerning the O2 sensor. Is there a way
> to
> > check them? I don't have any error codes, but I think that the
downstream
> > sensor close to the cat converter is not working. I have a '97 GC.
> thanks!
> >
> >
>
>

Jerry Bransford

The downstream 02 sensor, unlike the upstream 02 sensor, has no ability to
adjust the fuel mixture or for that matter, anything about how the engine
runs. Its sole function is to check the cat for proper function and display
a Check Engine light if it detects that the cat has gone bad.

Jerry
--
Jerry Bransford
To email, remove 'me' from my email address
KC6TAY, PP-ASEL
See the Geezer Jeep at
http://members.***.net/jerrypb/

"Cal" <codom1@triad.rr.com> wrote in message
news:ykWeb.17848$xB4.9228@twister.southeast.rr.com ...
> Even after a 50 mile or more warm up period, my 'catalyst' monitor is
never
> ready with a scan tool. I would like to be able to test the O2 sensor
> downstream from the converter to see if it is bad. I think this may have
> been a problem for a while. It may be related to a carbon problem I seem
to
> have on occasion. My dealership has had this jeep for up to 2 days (when
it
> starts to misfire) and they have never been able to correct it. A bottle
of
> good fuel injector cleaner always 'fixes' it though. I have had thin, hard
> carbon deposits on several plugs in the past, and suspect that incorrect
> data from O2 sensors and rich fuel is probably to blame. I know there
have
> been lots of comments about 'ordinary people' having scan tools on this
> site, but, apparently, some dealerships don't need them either.
> "TJim" <jim@ranlet.nospam.com> wrote in message
> news:MDOdnVZF6I8gseGiU-KYgg@comcast.com...
> > Why do you think that?
> >
> > --
> > Jim
> > 98 TJ SE
> > 90 SJ GW
> > http://www.delawareja.com/gallery/JDJeep98
> >
> >
> > "Cal" <codom1@triad.rr.com> wrote in message
> > news:CYVeb.17738$xB4.13406@twister.southeast.rr.co m...
> > > I've seen lots of posts lately concerning the O2 sensor. Is there a
way
> > to
> > > check them? I don't have any error codes, but I think that the
> downstream
> > > sensor close to the cat converter is not working. I have a '97 GC.
> > thanks!
> > >
> > >
> >
> >
>
>

Jerry Bransford

The downstream 02 sensor, unlike the upstream 02 sensor, has no ability to
adjust the fuel mixture or for that matter, anything about how the engine
runs. Its sole function is to check the cat for proper function and display
a Check Engine light if it detects that the cat has gone bad.

Jerry
--
Jerry Bransford
To email, remove 'me' from my email address
KC6TAY, PP-ASEL
See the Geezer Jeep at
http://members.***.net/jerrypb/

"Cal" <codom1@triad.rr.com> wrote in message
news:ykWeb.17848$xB4.9228@twister.southeast.rr.com ...
> Even after a 50 mile or more warm up period, my 'catalyst' monitor is
never
> ready with a scan tool. I would like to be able to test the O2 sensor
> downstream from the converter to see if it is bad. I think this may have
> been a problem for a while. It may be related to a carbon problem I seem
to
> have on occasion. My dealership has had this jeep for up to 2 days (when
it
> starts to misfire) and they have never been able to correct it. A bottle
of
> good fuel injector cleaner always 'fixes' it though. I have had thin, hard
> carbon deposits on several plugs in the past, and suspect that incorrect
> data from O2 sensors and rich fuel is probably to blame. I know there
have
> been lots of comments about 'ordinary people' having scan tools on this
> site, but, apparently, some dealerships don't need them either.
> "TJim" <jim@ranlet.nospam.com> wrote in message
> news:MDOdnVZF6I8gseGiU-KYgg@comcast.com...
> > Why do you think that?
> >
> > --
> > Jim
> > 98 TJ SE
> > 90 SJ GW
> > http://www.delawareja.com/gallery/JDJeep98
> >
> >
> > "Cal" <codom1@triad.rr.com> wrote in message
> > news:CYVeb.17738$xB4.13406@twister.southeast.rr.co m...
> > > I've seen lots of posts lately concerning the O2 sensor. Is there a
way
> > to
> > > check them? I don't have any error codes, but I think that the
> downstream
> > > sensor close to the cat converter is not working. I have a '97 GC.
> > thanks!
> > >
> > >
> >
> >
>
>

Cal

Thanks!
"Jerry Bransford" <jerrypb@mecox.net> wrote in message
news:bvWeb.37369$gv5.16849@fed1read05...
> The downstream 02 sensor, unlike the upstream 02 sensor, has no ability to
> adjust the fuel mixture or for that matter, anything about how the engine
> runs. Its sole function is to check the cat for proper function and
display
> a Check Engine light if it detects that the cat has gone bad.
>
> Jerry
> --
> Jerry Bransford
> To email, remove 'me' from my email address
> KC6TAY, PP-ASEL
> See the Geezer Jeep at
> http://members.***.net/jerrypb/
>
> "Cal" <codom1@triad.rr.com> wrote in message
> news:ykWeb.17848$xB4.9228@twister.southeast.rr.com ...
> > Even after a 50 mile or more warm up period, my 'catalyst' monitor is
> never
> > ready with a scan tool. I would like to be able to test the O2 sensor
> > downstream from the converter to see if it is bad. I think this may
have
> > been a problem for a while. It may be related to a carbon problem I
seem
> to
> > have on occasion. My dealership has had this jeep for up to 2 days
(when
> it
> > starts to misfire) and they have never been able to correct it. A
bottle
> of
> > good fuel injector cleaner always 'fixes' it though. I have had thin,
hard
> > carbon deposits on several plugs in the past, and suspect that incorrect
> > data from O2 sensors and rich fuel is probably to blame. I know there
> have
> > been lots of comments about 'ordinary people' having scan tools on this
> > site, but, apparently, some dealerships don't need them either.
> > "TJim" <jim@ranlet.nospam.com> wrote in message
> > news:MDOdnVZF6I8gseGiU-KYgg@comcast.com...
> > > Why do you think that?
> > >
> > > --
> > > Jim
> > > 98 TJ SE
> > > 90 SJ GW
> > > http://www.delawareja.com/gallery/JDJeep98
> > >
> > >
> > > "Cal" <codom1@triad.rr.com> wrote in message
> > > news:CYVeb.17738$xB4.13406@twister.southeast.rr.co m...
> > > > I've seen lots of posts lately concerning the O2 sensor. Is there a
> way
> > > to
> > > > check them? I don't have any error codes, but I think that the
> > downstream
> > > > sensor close to the cat converter is not working. I have a '97 GC.
> > > thanks!
> > > >
> > > >
> > >
> > >
> >
> >
>
>

Cal

Thanks!
"Jerry Bransford" <jerrypb@mecox.net> wrote in message
news:bvWeb.37369$gv5.16849@fed1read05...
> The downstream 02 sensor, unlike the upstream 02 sensor, has no ability to
> adjust the fuel mixture or for that matter, anything about how the engine
> runs. Its sole function is to check the cat for proper function and
display
> a Check Engine light if it detects that the cat has gone bad.
>
> Jerry
> --
> Jerry Bransford
> To email, remove 'me' from my email address
> KC6TAY, PP-ASEL
> See the Geezer Jeep at
> http://members.***.net/jerrypb/
>
> "Cal" <codom1@triad.rr.com> wrote in message
> news:ykWeb.17848$xB4.9228@twister.southeast.rr.com ...
> > Even after a 50 mile or more warm up period, my 'catalyst' monitor is
> never
> > ready with a scan tool. I would like to be able to test the O2 sensor
> > downstream from the converter to see if it is bad. I think this may
have
> > been a problem for a while. It may be related to a carbon problem I
seem
> to
> > have on occasion. My dealership has had this jeep for up to 2 days
(when
> it
> > starts to misfire) and they have never been able to correct it. A
bottle
> of
> > good fuel injector cleaner always 'fixes' it though. I have had thin,
hard
> > carbon deposits on several plugs in the past, and suspect that incorrect
> > data from O2 sensors and rich fuel is probably to blame. I know there
> have
> > been lots of comments about 'ordinary people' having scan tools on this
> > site, but, apparently, some dealerships don't need them either.
> > "TJim" <jim@ranlet.nospam.com> wrote in message
> > news:MDOdnVZF6I8gseGiU-KYgg@comcast.com...
> > > Why do you think that?
> > >
> > > --
> > > Jim
> > > 98 TJ SE
> > > 90 SJ GW
> > > http://www.delawareja.com/gallery/JDJeep98
> > >
> > >
> > > "Cal" <codom1@triad.rr.com> wrote in message
> > > news:CYVeb.17738$xB4.13406@twister.southeast.rr.co m...
> > > > I've seen lots of posts lately concerning the O2 sensor. Is there a
> way
> > > to
> > > > check them? I don't have any error codes, but I think that the
> > downstream
> > > > sensor close to the cat converter is not working. I have a '97 GC.
> > > thanks!
> > > >
> > > >
> > >
> > >
> >
> >
>
>

bllsht

Actually, the PCM will use downstream O2 input to "fine tune" fuel trim in
addition to monitoring the cat.

The OP didn't say what engine he had, but there's a TSB for 4.0L engines
concerning decarbonizing the combustion chamber and revised valve springs.



In message <bvWeb.37369$gv5.16849@fed1read05>, "Jerry Bransford" wrote:

>The downstream 02 sensor, unlike the upstream 02 sensor, has no ability to
>adjust the fuel mixture or for that matter, anything about how the engine
>runs. Its sole function is to check the cat for proper function and display
>a Check Engine light if it detects that the cat has gone bad.
>
>Jerry