Hello everyone this is my first post. I have a 1996 Audi A4 Quattro. When I try to start it up after it has been sitting for awhile it take a while to crank. When it starts upit lets out a poof of dark smoke. I know I have a fuel problem somewhere. The check engine light is on and it reads that the coolant temp. senor is bad. I got the car from my brother in law who said he put a new sensor on about six months ago. When it starts it runs fine, it just when it sets it takes a while to crank up. Where do I start? Thanks for the imput.

 

Replace the ECT Sensor again. When I had my 96 12v, I went through about three of them (in less than a year) because they seem to have a very high failure rate. If you go to the dealer for the ECT sensor, you might want to see if they warrantee the part, just in case the new one doesn't work.