Originally Posted by Mathias
HI!
When I start my 4x4 Sierra the idle speed is increased (normal
when the engine is cold), after a few seconds it drops to ~900rpm
and then it starts to rise to appr. 1200rpm and will stay there.
Cleaned the ISCV but no change. What will happen if I disconnect
the ISCV? If it drops to normal revs will it mean that the ISCV
is not working properly?
If the ISCV is okay, what else can cause this problem?
regards
Mathias
May be you have an electronic problem. Hight idle speed (1.200 / 1.400 rpm) is a signal (only with L8 and P8) that something wrong on your sensors.
Do an autodiag.
Regards
Claude