URQ fuel pressure numbers

[Ameer Antar]

the warm control pressure sounds a little low, which would cause a rich 
mixture. Usually it's around 55psi or so, but not positive for ur-q. Check 
the plugs for rich running. Also check the warm up regulator harness for a 
constant 12V when the car is on. The regulator itself should be 17-21 ohms. 
Otherwise, the heating elements are probably too old and are not heating up 
the valve inside, causing low warm pressure.

But, sounds like something could easily be wrong w/ some sensor in the 
ignition/CIS system. It's very hard to tell w/o performing all tests 
following Bentley procedures. It could simply be a sensor cutting out, or 
could be a part that's actually bad. The frequency valve might not be 
seating properly or is seizing, giving you jumpy duty cycle. The duty cycle 
normally moves around, but you should be able to center it around 50%. The 
freq. valve is the one that actually changes the mixture according to O2 
sensor output. Also there might be some blockage somewhere. All these are 
hard to diagnose w/o a good manual. Another good book is the Bosch F.I. & 
Eng. Mgt. by Charles Probst. It tells you exactly how the system works. 
good luck.

-ameer

At 10:17 AM 10/27/00, you wrote:
>Thanks to Smitty, Ameer, & Phil for the quick responses.
>The readings I got from my car were;
>         warm (not hot, set 1.5 hours)   system-33 psi  2.27bar
>         fully warm                      system-49 psi  3.41bar (after app. 3
>min.)
>         fully warm                      control -89 psi  6.14bar
>         residual (20 min.)              system-35 psi  2.41bar
>Are those close enough or is there some tweaking to be done.
>The frequency valve will not stabilize. Two degrees either way on the 3mm
>allen screw sends it to 63.1 or 4.8. If I dial it into 49.1 it will stay
>there until driven and then migrate to one end or the other. The crackle on
>decel at the exhaust either gets worse or goes away, indicating mixture
>problem??
>FPR resistance is spot on, and O2 sensor is new. Car sometimes runs perfect,
>other times feels that it leans out and/or goes rich. I have wired the FV
>meter to the interior, and monitor it regularly.
>I'm sooooo close. It appears that some sensor isn't performing to spec. Temp
>sensor is also spot on for resistance values.
>Any ideas?
>
>Dennis