Hard start & rough idle when cold

[Huw Powell]

"The O2 sensor is new and reads .5v with very little fluctuation."

Then it's not reading (sorry not get to this earlier, thought of it 
while grocery shopping).  The wire from the ECU itself will read 0.5 
volts.  On a non-managed engine, the OXS will almost certainly read 
almost zero or almost one volt.  Are you sure it's plugged in properly? 
  Did this problem, um, start when you replaced it?

Try reading its output while revving the engine up and down a few times...

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/