sod

This morning I went to check the ECT sensor on my son's 1990 Audi 100. You may recall you suggested that it my be the cause of the car's hard start when cold problem. You sent a link to show the sensor's location.

Well, now I am really confused. The car doesn't have a ECT sensor in that location. Nor are there any lose wires that would suggest that there was once a sensor and it is no longer on the car.

Any thoughts? And again thanks for the help todate.

audiqv8

That link that I posted was for a turbo engine. If you have a non turbo engine look for the ECT at the back of the cylinder head.

Have you tried blinking out the DTC codes??? Do you have a Bentley or Haynes manual???

Audifahrer

CIS III does not have the sensor on the back of the engine. The CIS-E (Audi 5000 1985-early 87) does. With CIS III the input comes from the temperature sensor on the coolant flange between engine head and the upper radiator hose. Now there are 2 of them, and it is the one on the top. The colder it is outside the temperature resistance reads higher. Information from it goes to the fuel injection ECU (passenger side footwell), which in return grounds the cold start valve and makes it spray fuel when cranking the engine. I had just fixed a friends CIS III, where it was the ECU at fault. Other than that it run just fine. If you do get voltage on the cold start valve connector plug, the ECU is fine, the sensor too. I had experienced in 10 years of Audi ownership failure of the actual valve itself too.
Zoran in Toronto