Engine hunting at idle - first time it happened

I never had this type of a problem on my E36 or
my current E46 until now - while car was stopped at an intersection and at idle, the rpm dropped from the normal 750, and suddenly went up very high (over 3000 ) - happened a number of times - any clues ?

Thx,
Peter
'00 328Ci

if your car also feels a little under-powered in normal driving, it's probably the intake cam sensor.

If the sensor was broken, would that generate a fault condition ? Would the check engine light come on ? I have seen a procedure for older Motronics to get the fault codes by pressing the gas pedal 5 times - it does now work on E46 - any other way short of a ODB scan tool ?

Thx,
Peter

yes, you can get a fault code reader to check the codes, the code i'm reffering to is 41 i believe.

the check engine light may or may not come on. if you let it go long enough it will come on when the engine gets a low fuel level to the engine due to the cam sensor not working correctly.

you can purchase a fault code reader from www.turnermotorsports.com or www.bavauto.com. although just reading the code isn't going to do much. you could take it in, it's under warranty.

I have the Bently e46 manual - will read up on the cam sensor - having the scan tool even with the car under warranty might be nice - I may look into building one as I am an EE and have access to a microcontroller development tools - just need to find ODB2 protocol info - will do google search - maybe someone has good pointers ;-)

Thx,
Peter