[V8] 2ns Running Rich

[urq]

The instrument cluster cannot create anything that would cause the engine to
run poorly.  The one thing that seems to be characteristic of the PT engine
is that it can tend to run richer when the engine cools from idling for a
while (I've seen similar results with the I5T engines).  The last time I had
#2 smogged the tech actually let the engine run at 2500 RPM for a few
minutes before plugging in the probe and running the test ... the car passed
with its usual low emissions.  

If you've already done all of the standard tune up items (air/fuel filter,
spark plugs, caps and wires, OXS) you're going to need to dig in a little.
Have you verified the fuel pressure at the injectors?  It could be that the
FPR is providing too much pressure, so the engine is running rich.  If you
know the fuel pressure is good you will want to consider things like using a
VAG-COM or ProDiag setup to read out codes and verify things like the
coolant temp sender is reading the correct temp.  I'd also try "reading the
spark plugs (go out for a run and shut the engine down when the engine is
good and warm and hasn't idled very long ... now pull out the spark plugs
and look at the condition of the center electrode insulator to look for
cylinders that aren't running right).  You would also want to look at
compression and leakdown tests.  Another thing to do is to evaluate whether
or not the catalytic converters are doing their job.  

Now that I'm thinking about it, ISTR reading somewhere that the engine can
run more rich when the fuel tank is getting low.  This is not intuitive to
me ... has anyone else heard this?  I do try to make sure the tank is full,
and I usually put in some injector cleaner to push the emissions in my
favor.  

Good luck!
Steve B
San José, CA (USA)

-----Original Message-----

I have failed to get my car to pass emissions.  I replaced the 
Plugs(they were a wide gap), rotors, caps, Air Filter and the head temp
sensor. 

NOTE: the rotor  Bosch #04170 part firts perfectly and only $4.22 @ 
autohausaz.com.

I replaces the Ox sensor only 12,000 mi ago.  Could it be bad so soon?  
What is the Bosch part number for the 4 wire ford replacement? I'll but 
another one.

*** -> I have some gremlins with the instrument cluster, could this be a 
source of the problem?  Does the ECU use signals from the IC?

Any advice is appreciated.