Hesitation at Start Up 2008 Colorado 5 cyl
2008 Colorado 5 cyl Z71 138000 miles
Problem: Sometimes at start up after engine is at operating temperature and is shut off for a length of time (greater than an hour), which seems to vary based on outside temperature. Engine will hesitate at startup. RPM drops to almost zero jumps to 2000, back to zero up again and finally settles in at a little less than 1000 slowly drops to around 650.
Replaced Mass Air Flow
Replaced Camshaft Solenoid
Replaced Throttle body and sensor (Dealer replaced)
Cleaned PVC valve
Doesn’t exhibit problem when cold, never a problem with first start in morning.
If engine is shut off when hesitation starts it will not exhibit problem when immediately restarted.
Can shut off and restart multiple times and it will not exhibit problem.
Seems that it’s related to temperature of engine or related parts.
Never have seen a Check engine light