Re: UrQ Cold Driving Problem

[Robert Houk - WorkGroup Server Firmware <Robert.Houk@East.Sun.COM>]

   This problem has plagued me since owning the UrQ, or was it since having
   it chipped by TAP?

If you're running the stock cam, I shouldn't think it's anything that
TAP did (assuming they didn't do anything really, um, strange).

                       When I start the UrQ it starts right up but requires
   a couple of very light taps on the throttle, light enough to not blip

I often see this with mine too; I accept it as part of life.

   the engine, to keep running. Once started it runs perfectly even in the
   coldest weather until approximately 3 minutes after starting, at which
   point it idles very roughly and will stall if I don't raise the idle
   speed a little.  This happens with a hot or cold engine, but occurs more
   rapidly with a hot engine that has sat for more than 15 minutes. It does
   not happen to a hot engine that has sat less than 15 minutes.

   When I look at the duty cycle, the problem occurs right as the car goes
   into open loop (OX is working). After a few more minutes of behaving
   like this, it drives and idles fine but I always come to a stop light at
   the bottom of my hill in the morning right at the problem time and it's
   a PITA. The car backfires or pops lightly when decelerating during this
   period (I have a very open exhaust, sleeved kitty, etc so it's always a
   little more noisy on decel) The duty cycle goes from the preset value to
   jumping around in the 90's and when it settles into a good idle again
   it's near 50% and jumping around like it should. RDH told me that the
   UrQ has too short of a warmup period, but how do I correct this problem?
   Should I set the idle speed to the correct value, tune up the car and
   then raise the idle speed to 1000 rpm? Please help, I can't stand this
   problem.

What's your "fully warmed up" idle? I target mine to 950, with the
ECU ROM targeting 920 (as I recall) minimum (stock is 820, I think???)

If, fully warmed up, your duty cycle is holding 50% (+/-), then your
static mixture is pretty good.

Stock, the ECU goes closed loop when the block temp is circa 90F (and,
of course, O2 sensor responding); I extended mine (Schrick cam) to
around 130F before going closed loop. I suspect the stock cam might
like the extension, but it shouldn't require it.

I would tend to suspect either your control pressure regulator is
"warming up" (leaning out) too early (as indicated by the duty cycle
being ramped way up), or your aux air valve is "warming up" (closing
off) too early. Does the idle speed "drop precipitously" during this
rough idle period? If so, I'd suspect that the aux air valve is not
opening enough (and/or closing too early). It's adjustable (some-
what), try opening it up a little. I tend to crank mine all the way
open in winter, and 'bout halfway during summer; all the way open
typically results in a fast (1200RPM) idle for a minute or so after
a couple of minutes of driving [cold start, drive two minutes, idle
is "high"; cold start, no drive, just let engine idle/warm up, then
the idle is "normal"]. It's unfortunately a totally "static" system,
no feedback control, so it's a matter of picking the set of compro-
mises that works least badly...

Good luck!

					-RDH