Re: Heat & My ur-q don't mix

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

   We recently had a warm spell here in Southern Cal.  The temp probably got
   up to about 90-95.  I was returning from the Drive up Angeles Crest Highway
   with the local chapter of the Q-Club.  I his traffic and was moving at 5
   mph for about 45 min.  After being in traffic for a little while the car
   would not idle on its own.  I had heel and toe just to keep it running.  I
   have since installed a manual switch for the injector cooling fan and
   insulated the fuel lines running to and from the control pressure
   regulator.  The problem still occurs even if I run the injector cooling fan
   anytime I am below 20 mph.  The A/C was on until the car started running

Running the AC will actually help cool the engine (forces the rad fan to
Hurricane Force setting).

   rough.  When I turned it off it did not help.  The temp gauge was not

What do you have for a temp guage, and where is it connected?

   reading hot.  When the traffic cleared I had NO power.  The 0-60 time was
   about 2 min.  I could barely keep it at 60.  After driving in the slow lane
   for about 15 min hoping that I would not have to be towed.  The engine

Would it rev readily in neutral, or was it sluggish irrespective of
applied load? Could you tell if it was "obviously" running rich or lean?

   suddenly surged a few times and then all 160 hp was returned like nothing
   was wrong.  

   Any suggestions?

Wow, that's one even mine hasn't come up with (Quiet! you'll give it
ideas...)

   Would reduced voltage do something like that to the computer?

I should think that highly unlikely -- the ECU will most likely just
completely fu, er, ah, fail...

   Am I experiencing vapor lock. (where)

Doesn't really sound like it, especially if it took 15 (!) minutes of
driving to restore the system (vapor lock should just take a few seconds
to blow it (vapor) out of the injectors (assuming that's where the
vapor-lock occured).

Aside -- I've never seen any use for the injector cooling fan, hot
LA/SJ-valley summers, 100+, hot engine, it would never come on by
itself; installing a manual switch to force it on never seemed to make
any difference in restarting the engine either. I finally just pulled
the whole damn thing out. Makes it a lot easier to get to the plugs...

   Does the control pressure reg (fuel boiler) need to be attached to the
   block or can it be located in a cooler environment?

It needs the (lower block, away from the exhaust manifold) block to heat
it up properly (to set proper "warm engine" fuel backpressure) for proper
overall mixture.

Dunno quite what to say, other than some quasi-random speculations.

First, irrespective of this problem, I'd install a lower-temp thermostat
and rad fan switch (I'm running the 180F setup). But I really don't
think that's your problem here.

The "idle" problem almost sounds like air leak, but I don't see how
an air leak would affect performance across the board...

Maybe fuel pressure? Fuel pump?

It really doesn't sound electrical in nature...in my experience...I
think I'd concentrate on fuel delivery -- mount a pressure gauge to
monitor overall system pressure, and pressure to the injectors.
Monitor the Frequency Valve output (duty cycle) from the ECU to see
what the ECU is trying to do with the system (that'll tell you if
the mixture is going rich or lean; reading the O2 sensor directly
will tell you which way the ECU *should* be pushing the mixture),
that can tell you a lot, very easily. (Have you bought yourself a
SunPro 7678 yet? Do they even still make it? The duty-cycle readout
is invaluable for maintaining the UrQ (mid-80's) cars.)

I wish you luck, those beasts can be a real challenge!

					-RDH