172 eratic RPM limiter

[Ronney]

Hi all I am new to this and the call for help is from south africa
I have a 172 that the rpm limiter is eratic sometime it will come in at 7000 rpm and some times at 6000 rpm .
This not water temp related as it does it even when at operating temp and no fault codes on the ecu.

thanks

 

[TimR26]

There's a cold limiter which should kick in at 6.8k then when up to temperature the rev limit is 7.2k.

I think the cold limiter is based on the water temperature so it could be a problem with the coolant temperature sensor or thermostat.