LarryF_in_Ca

Checked Cold Start injector, if sprays beautifully. Problem when checking cold start injector (Temp was around 50 degs here in Calif).

The damn car seems like the ignition switch is bad, but only when cold.

After getting the car started, I was able to drive is around and let it idle, it idles dead on "first tick mark" before 1000 rpm.

After the run, I shut off the car, and the injector cooling fan started to run, I immediately checked for the turbo water pump, no go, and the radiator fan also wasn't working. I then shorted the water temp switch leads, and the radiator fan and turbo cooling pump both work.

QUESTION:
What water temp switches if not working, will make the car hard to start up cold and warm??

Has anybody used those electrical relay contact sprays, and if so what success if any have you guys had with using these cleaners?

I think I need to go through each and every electrical connector and make sure the there is good contact.

Any Suggestions??

audiqv8

Go to the following link and scroll down until you see the picture of all the sensors mounted to a turbo engine.

I guess the one of the more important sensor is the engine coolant sensor which tells the ECU the engine coolant temperature.

"I then shorted the water temp switch leads, and the radiator fan and turbo cooling pump both work." I guess you know that this sensor might be bad or just needs to be cleaned. Remove the sensor and see if it is cake on with gunk which is acting as an insulation.<ul><li><a href="http://www.sjmautotechnik.com/trouble_shooting/10vcoolt.html#coolt">Sensors</a></li></ul>

JAMS6

My car was hard to start both cold and hot...or maybe not hard to start but hard to keep running. When cold, the car would run only if I fluctuated the throttle for a minute or so and would stumble and not have power until it warmed. When the car was hot started, it would stumble similarly to when it was cold started. I went through the cold start circuit and found everything working correctly.
Anyway, my wrench/friend found that the mixture was too lean. He richened the mixture and the car is completely different. There was also a hesitation when boost came up as well.
Anyway, hope this helps you. Sure would be nice if its that easy for you as well.

JAMS6

Another sensor I tested on mine. I think they rarely fail but are easy to check.

RussB

Just replace the after-run coolant temperature sensor. Any Audi parts vendor can supply them. I like to use Worldpac vendors such as sjmautotechnik but there are plenty of others.

Yes, contact cleaners (usually toluene or trichlorethylene + propellant) have their place but won't help you in this particular case.

Have a read of this post regarding protection of electrical connections:<ul><li><a href="https://forums.audiworld.com/v8/msgs/67373.phtml">https://forums.audiworld.com/v8/msgs/67373.phtml</a</li></ul>