nikj_dk

The car is a Audi Cabriolet 2.3E from 1993. When starting the motor from cold, revs are 800, but when it gets warm, it goes to 1200 revs. What could be the cause of that?
Regards.

Hendie

When your engine reaches operating temp (open loop)your ecu then starts taking signals from various sensors and uses that info to modify the fuel trim. Sounds like a possible defective sensor. Check engine light on with any codes? It runs fine untill it gets to operateing temp? Sounds like a open loop sensor issue. I'd test your O2 sensor(s) maybe a weak signal making the ecu think the engine is running lean so it gives it more fuel. And look for things that input to the ecu during open loop and test those as well (MAF, MAP ext...) Hope this helps some. These cars aren't really in my wheelhouse. But a engines an engine and I saw no one had replied to your post yet. I'd look into a Bently manual if you don't have one and plan on doing the work your self. My Bently manual saved me thousand$ in labor cost, thousand$! Don't forget to search the forum😁 Good luck and post any engine trouble codes you may have, stored in the ecu.