revs are not idle revving up an down on its own..

[Lee Norris]

Hi
put a k11 march engine into my autograss car the engine is starting perfect ,the revs stay idle but when i press on the revs an take my foot off the revs go off on there own not extreme revving up and down stil doing it idle?? any ideas please help racing in weeks time so gotta get it fixed thanks lee.!

 

[Lee Norris]

anyone have a clue what it might be ..

 

[pollyp]

if the idle screw was open too far or the idle control valve was excessively out of calibration that the ecu can't control idle, it may cause the idle to hunt around

check this
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-19#post-446256

 

[Lee Norris]

what if i put in the ecu from the march shell which the eninge was connected to before ,because the last engine it before had the same problems ,i changed the throttle body but it had no difference i thought maybe the engine was wanked maybe .

 

[solarice]

what if i put in the ecu from the march shell which the eninge was connected to before ,because the last engine it before had the same problems ,i changed the throttle body but it had no difference i thought maybe the engine was wanked maybe .

Easiest place to start. Seeing as you've swapped out the engine and problem still exists between the two. Vac leaks would be worth looking for as well.