Sorry for showing you the dirty rag

I don't want you to feel uncomfortable seeing this but I want you to know how the throttle valve became

clogged by the carbon.

This is the throttle valve of my old Celsior UCF21. The lower half was just cleaned by the rag

above with alcohole. Still upper half is not yet cleaned. After cleaning all, the rag was totally

blackened and I'd better not to show it.

 

The reason why I decided to clean the throttle valve was too low rpm at idle. It was 400rpm or less sometimes. After running 145,000km, the car was aged and there happened some minor problems.

But still it runs great and I don't have any serious problem that I used to have when two German cars

were in use when I was younger  one in Japan and the other in US. I dare not mention which

company's car those were but I simply got a conclusion that no more German cars for me.

 

Anyway, after cleaning and removing the carbon clogged at the valve and the body, the idle rpm

went up higher than normal around 1600rpm at P and 1100rpm at D4 position. I tried to adjust

manually turning the screw that sets the home position of the valve but there was no luck.

But driving the car in the city for 30 minutes, everything became OK. The idle is 750rpm at P and

600rpm at P4. The ECU has studied the situation. How smart the car is.