[urq] Lack of power untill up to temp

[Brandon Rogers]

Here are my thoughts-  Sounds like the computer doing it's warm up thing in
conjunction with the Warm Up Regulator doing it's thing-namely controlling
fuel pressure as the cars warms up.  Basically- At initial start-up the
motor is cold and the ECU fixes duty cycle at 49.9% - the motor idles very
nice and smooth here.  After a few minutes the system goes to the other mode
(I always get confused on Open vs Closed Loop) and starts to listen to the
O2 sensor.  This is when the DC fluctuates around trying to maintain the
proper mixture- this is also when it starts stumbling for a while.  I
believe there is code in the ECU that leans out the mixture for a brief
period to heat up the cats on the US models - enter stumbling.  You can get
rid of this leaning out period with custom ECU code - not sure who's doing
code for urq computers these days - I _think_ Steve Eiche no longer does urq
ECU code/chips...Ned Ritchie at IA?  As for the WUR it has a temperature
sensitive element that increases ( I think) fuel pressure as the car warms
up- if it's not working your fuel pressures get goofy and you get poor
running.  New they are $$$$, but you can get them cheap at salvage yards.
Hook up a fuel pressure gauge and check out the behavior before swapping,
IMO.

hth a little....

Brandon

----- Original Message ----- 
From: <MikeDes156 at aol.com>
To: <urq at audifans.com>
Sent: Tuesday, September 07, 2004 9:12 AM
Subject: [urq] Lack of power untill up to temp


> Here's what's been happening. Car (83 urq) starts fine as always, but
sounds
> a little like it's running on four cylinders for a few seconds, then it
> straightens out. (Maybe one of the injectors lets fuel enter the cylinder
while it's
> sitting.) The car will run fine untill I floor it, and then it seems to
> stumble (back to running like it's on four cylinders) with a change in
exhaust
> sound and power. Seems to happen around 12psi of boost. RPM dosen't seem
to be the
> same when it happens. But once I've driven the car for 10-15min, it runs
fine
> again. I can even let the car sit for an hour or so and it still runs like
it
> should. The last thing I did on the car was replace the igloo with a later
> type (for looks), but I don't think that should change anything.
Injectors, fuel
> pump, sensor, distributor?  Not sure where to start.
>
> Mike D.
> #900459 Gobi
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