'04 running rich

For those of you who like diagnosing strange problems I have a doozy
for you.

The symptoms are as follows: Very rich smelling exhaust, inside of
tailpipe VERY thickly coated with soot, badly carboned plugs.

I have checked the following: Manifold vacuum (20 ish in/Hg at idle in
gear), done an aceytelene test around the intake and throttle-body
gaskets/assemblys. The OBD system reports NO PROBLEMS, the mpg figures
are all over the map over the past 2 months I have gotten from 14 to
33! mpg using the same brand/grade of fuel driving the same routes
every week. I have made NO changes to the vehicle WHAT SO EVER.

This has me stumped.

How about you.

On Tue, 22 May 2007 20:58:35 -0300, wrote:

>For those of you who like diagnosing strange problems I have a doozy
>for you.
>
>The symptoms are as follows: Very rich smelling exhaust, inside of
>tailpipe VERY thickly coated with soot, badly carboned plugs.
>
>I have checked the following: Manifold vacuum (20 ish in/Hg at idle in
>gear), done an aceytelene test around the intake and throttle-body
>gaskets/assemblys. The OBD system reports NO PROBLEMS, the mpg figures
>are all over the map over the past 2 months I have gotten from 14 to
>33! mpg using the same brand/grade of fuel driving the same routes
>every week. I have made NO changes to the vehicle WHAT SO EVER.
>
>This has me stumped.
>
>How about you.
Gee, how to reply to my own post, DUH.

Just some more info, the engine is a 4.0L (242 CID), with less than
50,000 km hooked to a 4 spd auto trans with a 3.55 ratio rear end.

One more note there appears to be NO loss of power and NO smoke out of
the tailpipe.

Strange eh?

Kevin

02 sensors and map sensors come to mind first

wrote:

> For those of you who like diagnosing strange problems I have a doozy
> for you.
>
> The symptoms are as follows: Very rich smelling exhaust, inside of
> tailpipe VERY thickly coated with soot, badly carboned plugs.
>
> I have checked the following: Manifold vacuum (20 ish in/Hg at idle in
> gear), done an aceytelene test around the intake and throttle-body
> gaskets/assemblys. The OBD system reports NO PROBLEMS, the mpg figures
> are all over the map over the past 2 months I have gotten from 14 to
> 33! mpg using the same brand/grade of fuel driving the same routes
> every week. I have made NO changes to the vehicle WHAT SO EVER.
>
> This has me stumped.
>
> How about you.

> wrote in message
...
> For those of you who like diagnosing strange problems I have a doozy
> for you.
>
> The symptoms are as follows: Very rich smelling exhaust, inside of
> tailpipe VERY thickly coated with soot, badly carboned plugs.
>
> I have checked the following: Manifold vacuum (20 ish in/Hg at idle in
> gear), done an aceytelene test around the intake and throttle-body
> gaskets/assemblys. The OBD system reports NO PROBLEMS, the mpg figures
> are all over the map over the past 2 months I have gotten from 14 to
> 33! mpg using the same brand/grade of fuel driving the same routes
> every week. I have made NO changes to the vehicle WHAT SO EVER.
>



I seriously doubt your Jeep can run rich and not throw an OBD II code as a
result. The O2 Sensor(s) are looking at the rich/lean condition, both before
and after the CAT.