Volvo 240

[hameed]

Engine running eraticly i.e. idle speed changing from ~1550-500rpm,
Lambda light is on. Checked lambda sensor its working ok. Tried ECU
from a volvo 340 same problem. Vehicle has been inspected by BOSCH
Center they recommended ECU problem, can someone please help with any
other possible causes??

 

[James Sweet]

Engine running eraticly i.e. idle speed changing from ~1550-500rpm,
Lambda light is on. Checked lambda sensor its working ok. Tried ECU
from a volvo 340 same problem. Vehicle has been inspected by BOSCH
Center they recommended ECU problem, can someone please help with any
other possible causes??

Vacuum leak is the first thing I'd suspect.