Running Rich - 92-4.0L

I have a 92 Wrangler, 4.0L that is running real rich. Plugs go black, black
smoke from exhaust.

I put a new O2 sensor in a month ago, but it is still running rich. I have
gone through and cleaned out the TB, and TPS & AIC sensors, still rich.

What else could cause this?

Les wrote:
> I have a 92 Wrangler, 4.0L that is running real rich. Plugs go black,
> black smoke from exhaust.
>
> I put a new O2 sensor in a month ago, but it is still running rich. I
> have gone through and cleaned out the TB, and TPS & AIC sensors,
> still rich.
>
> What else could cause this?

Cheap ones first.
- loose or broken vac line to the fuel pressure regulator?
That results in too high a fuel pressure under normal operation.
- Or too low a heat range on the plugs.
If they are running cold they will soot up.

Bad coil/weak spark that's not igniting each charge and letting some of
the fuel through. leaking injectors (but usually that's only on one cyl).
Clogged cat can result in backpressure problems.

Any fault codes?
http://autorepair.about.com/library/...l-dtcs-24a.htm

--
DougW

Intake air temp sensor.

Spdloader



"Les" > wrote in message
...
>I have a 92 Wrangler, 4.0L that is running real rich. Plugs go black, black
> smoke from exhaust.
>
> I put a new O2 sensor in a month ago, but it is still running rich. I have
> gone through and cleaned out the TB, and TPS & AIC sensors, still rich.
>
> What else could cause this?
>

A dirty air filter?

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Les wrote:
>
> I have a 92 Wrangler, 4.0L that is running real rich. Plugs go black, black
> smoke from exhaust.
>
> I put a new O2 sensor in a month ago, but it is still running rich. I have
> gone through and cleaned out the TB, and TPS & AIC sensors, still rich.
>
> What else could cause this?

> A dirty air filter?
>
Nope it's new
>
> Cheap ones first.
> - loose or broken vac line to the fuel pressure regulator?
> That results in too high a fuel pressure under normal operation.
> - Or too low a heat range on the plugs.
> If they are running cold they will soot up.
>
> Bad coil/weak spark that's not igniting each charge and letting some of
> the fuel through. leaking injectors (but usually that's only on one cyl).
> Clogged cat can result in backpressure problems.

Previous Owner cut a hole in the cat and clean out the guts. It does leak a
little, and I need to replace or bypass with a straight pipe
>
> Any fault codes?
> http://autorepair.about.com/library/...l-dtcs-24a.htm

No Codes


> Intake air temp sensor.
>
> Spdloader

Can these be tested with a meter?

Les wrote:

>> Intake air temp sensor.

> Can these be tested with a meter?

Yes. they are just temperature sensitive
resistors. (both mat and engine temp)
http://revbeergoggles.com/Fixes/diagnostics.html

--
DougW

"Les" > wrote in message
...
>
>
>> A dirty air filter?
>>
> Nope it's new
>>
>> Cheap ones first.
>> - loose or broken vac line to the fuel pressure regulator?
>> That results in too high a fuel pressure under normal operation.
>> - Or too low a heat range on the plugs.
>> If they are running cold they will soot up.
>>
>> Bad coil/weak spark that's not igniting each charge and letting some of
>> the fuel through. leaking injectors (but usually that's only on one
>> cyl).
>> Clogged cat can result in backpressure problems.
>
> Previous Owner cut a hole in the cat and clean out the guts. It does leak
> a
> little, and I need to replace or bypass with a straight pipe
>>
>> Any fault codes?
>> http://autorepair.about.com/library/...l-dtcs-24a.htm
>
> No Codes
>
>
>> Intake air temp sensor.
>>
>> Spdloader
>
> Can these be tested with a meter?
>
>

When the sensor goes bad, it reports a cold condition that causes the system
to go "full rich". Doesn't log a code, the computer just stays in cold start
loop. Very common on GM 4.3 engines too.
I don't have the operational parameters for testing with a meter, but
someone here will.

Spdloader

On 10/20/06 2:30 PM, in article Ts9_g.36203$iA5.20657@dukeread11, "DougW"
> wrote:

> Les wrote:
>
>>> Intake air temp sensor.
>
>> Can these be tested with a meter?
>
> Yes. they are just temperature sensitive
> resistors. (both mat and engine temp)
> http://revbeergoggles.com/Fixes/diagnostics.html


Cool, but its time to talk dummy language...

How does that table convert to an Ohms reading? My gauge (old needle type)
read from 0 to 1K.

Great Web Site!

Les wrote:

> Cool, but its time to talk dummy language...
>
> How does that table convert to an Ohms reading? My gauge (old needle
> type) read from 0 to 1K.

The table is in ohms, 0-1k is 0-1000. There is probably a scale setting
on your meter. Look for 10k or 100k. Worst off you can get a cheap digital
meter at RadioShack, AutoZone, PepBoys, etc.


> Great Web Site!

Les wrote:
>
> On 10/20/06 2:30 PM, in article Ts9_g.36203$iA5.20657@dukeread11, "DougW"
> > wrote:
>
> > Les wrote:
> >
> >>> Intake air temp sensor.
> >
> >> Can these be tested with a meter?
> >
> > Yes. they are just temperature sensitive
> > resistors. (both mat and engine temp)
> > http://revbeergoggles.com/Fixes/diagnostics.html
>
> Cool, but its time to talk dummy language...
>
> How does that table convert to an Ohms reading? My gauge (old needle type)
> read from 0 to 1K.
>
> Great Web Site!

You 'really' don't want the VOM anywhere near the computer sensors. The
load the meter puts on can fry computer circuits. Same for a test
light.

It's time to step up to a digital multimeter....

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)