Good afternoon everybody,

My name is Lucas, from the Netherlands and I own a 2000 323 BJ with the 1.5L ZL engine.
The car has 165.000km (just over 100k miles) and is in a very good state of maintenance.
It's idling at around 600 rpm which is too low.
it is objectively too low and it also feels like it's just a tad below where it is happy at.

I tried adjusting the idle according to the procedure explained in OEM mazda workshop manual.
It says, connect a wire to GND and TEN on the diagnostics port which puts the ECU is some sort of maintenance/adjustment mode I assume.
Then adjust idle to desired rpm and after that remove the wire again.

After I adjusted the idle to my liking (around 800rpm) and removed the wire as described, the rpm dropped again to earlier value.
When I connect again rpms go up again to the adjusted value.
But It doesn't want to stay at 800 without the wire connected.
What am I doing wrong here?

 

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