[V8] Fan runs when cold...

[urq]

.... not so sure about the brake cleaner & WD-40 on the ISV, but that should
only impact the way the engine idles ... 

The comment that the electric fan comes on when the engine is cold causes me
to cast doubt on your instrument cluster (yes, the IC controls the rad fan)
.... so it makes me doubt the reported coolant temperature on the gauge.  As
Cobram pointed out you may want to back things up with a measurement using
an IR temp meter on the radiator to be sure.

The passenger side fan is connected on the serpentine belt ... when the
engine runs the fan is going to turn ... no matter if it is 40 below or 100
above ... it is just that the fan speed will be lower with the lower
temperature due to the viscous clutch.  I've never researched enough to know
whether or not you could notice a difference in the fan speed at idle ... I
always assumed it was at higher engine speeds where the difference would be
noticed.  

If you confirm that the engine temp is truly remaining at 70degC then you
may want to look at the thermostat.  

Do you ever see any fault codes in the ECU?  Given all the things you've
done I'd start to think about an intermittent flywheel speed sensor, or
perhaps some bad teeth on the ring gear.  

The ECU and Instrument Cluster are independent, so there is no way that a
problem with the IC should cause some sort of running problem in the engine
.... there are connections between the automatic tranny controller and the
ECU though ... perhaps you can try pulling codes from the TCU as well ... 

Steve B
San Jose, CA (USA)

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

       I think I just realized this, but it makes sense.  Anyway, here's the
deal thus far:  Have a rough idle and run, pretty much always.  It is
slightly intermittent, with only a brief moment of correct operation
randomly when I'm driving.  I've replaced the FPR, cleaned my idle stab.
valve, cleaned the Intake air temp sensor and MAF.  Used brake cleaner then
WD-40 on the ISV, MAF cleaner on IAT/MAF.  The IAT looks to be in good
shape, however, I did notice a small piece of the plastic insulation missing
from just behind the rubber boot , but the wires appear to be sound.  The
Spark Plugs are new Autolites, the plug wires appear to be in great shape,
and my ohm readings are odd, but all consistent (likely my meter has a
problem) and the Cap/rotor's appear to also be in good shape.

       Ok, so that's the background.  What I just realized, but noticed a
few times thus far, is that my car doesn't come to operating temperature.
Highest I've seen it get is about 70*C or so, and that's with an hour
driving with some of it at 55mph.  I also noticed working on the car tonight
and testing things, that when I start it up in the ridiculous extreme cold,
the passenger side (larger of the two, mechanical) fan flips on, then the
drivers side cylced on as well, and off, etc.  Just thinking maybe I have a
sensor of some sort bad, not sure.  And I'd guess that the fan sensor and
engine temp sensor are seperate, but hopefully someone can make a connection
I'm missing.

      On top of this, an 02 sensor is on the way, I'm splicing in a 4 wire.
I also picked up a new Dizzy cap for troubleshooting purposes, just incase
I'm wrong.