1996 GMC Suburban Code PO306

JON HALE #1

MEMBER
1996 GMC SUBURBAN
V8
2WD
AUTOMATIC
205,000 MILES

I've replaced the valve stem seals, plugs, wires, cap, rotor, CPI fuel injector unit and it still runs rough when it's cold and idling. Any ideas?

Thanks.

Saturday, March 6th, 2010 AT 5:26 PM

1 Reply

RASMATAZ

MECHANIC
75,992 POSTS

Engine running rough or misfiring can be cause by the following:

1. Defective spark plug.
2. Inadequate spark/coil, defective spark plug wire.
3. Lack of compression
4. False air leakage.
5. Faulty fuel injectors.
6. Insufficient fuel pressure.
7. Contaminated fuel.
8. EGR valve that is leaking.
9. Oxygen sensors.