1997
Mazda
MX3 (eunos 30 x in Australia)
1.8 V6
280 000km

At idle the rpm will race up to about 1500 rpm and then go back down to idle. It will then continue to race up and down. Sounds like im trying to race at the lights.
Has just had a service. The large hose from the air intake sensor to the engine was cracked so I replace it but this had no effect. No idea what to do next.
thanks for your help.

First make sure the engine is full of coolant....
You may have a bad IAC ( idle air control) but try cleaning the throttle body first. Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carb cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle. If it still has a problem, replace the IAC.




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