89 200 tqa - resolution of idle problems

[Samir Shah <gofast1@home.com>]

I swapped out the 'new' coolant temp sensor I had installed a few months
ago when I bought the car, and put in the old one I had taken out. The
'new' one appeared to have a pin that could be rotated, so I suspect it
was giving an intermittent connection, even though the resistance when
cold and warm appeared correct. Well, idle problems are gone, and car is
moving along strongly. 

I also first discovered that the idle and a/c coolant temp wires were
swapped. Correcting them did not appear to do anything, now making me
suspect that the other sensor is bad too, and may be why the a/c is not
functioning properly.

I also ran a whole slew of chemicals though the injection system - 4
cans of Ventil Sauber Fuel Injection cleaner, 2 cans of valve cleaner. 2
bottles of Techron concentrate, all with less than 1/8 tank. This is
after reading about Motorvac. It appears to have helped make the car
start and restart easier, + idle more smoothly. I am hoping this takes
care of any injector leakage it might be experiencing. 

To determine if I am getting a vacuum leak through the injectors - on
BMWs we direct propane over the suspect areas (like injector seals). If
the rpms increase, you've found the leak. Can I get away with doing this
on the Audi? Or are the injector seals buried too deep. The car is
running fine now, and I don't want to deal with pulling the injectors
and replacing seals (as I was planning on doing) if I can avoid it. Any
thoughts? The car supposedly has 72k miles.

Thanks to Scott Mockry's wonderful site for many ideas. 

Now, back to the damn a/c problems. My wife is going to be pissed
tomorrow cause we have to drive 100 miles to NJ tomorrow afternoon
without a/c...Samir.