Mk1 mx5 Revs on its own

[Hudson66]

I’ve recently fully rebuilt my mk1 mx5 1.6 bbr turbo.


When i start it, it takes a couple of turns to come alive then continuously bounces between 1.8 and 2.3k revs on its own.

When I apply some throttle it will stay at the revs I’ve selected and not bounce around.

I’ve changed the throttle body and idle valve from an identical car that works fine and the problem still stays on my car.

Any ideas what I should look at next?

[Mazda Mender]

1.8,1.6? Auto ,manual, ?import,uk, ? standard,boosted?,
M-m

[Hudson66]

1.6, UK, manual, BBR turbo

[Mazda Mender]

I will check my bbr manual in the morning, as I am unsure if it did have a ECU or piggy back management system.
M-m

[Mazda Mender]

It's either an air leak or the ICV is on its way out, you can try taking it off and giving it a good clean , it sometimes works...
M-m