Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Do you still have a catalytic converter? Have you checked the fuel pressure?
How old are the spark plugs and wires?
You cannot ever count on the CEL that is something that I will promise you right now. I have seen some things you would not believe. Anyways this is where I am at with it. I am pretty experienced when it comes to this stuff and saving you money on false repairs. Replacing the spark plugs I would do along with wires if everything else checks out. If that is not it we need to look at timing as a possible issue there. Note this is the least expected cause. Lets begin with the exhaust, Check the catalytic converter, on the "suspect" bank of the engine, for a restricted (plugged) exhaust system to that side of the engine. Disconnect both front O2 sensors, re-set the fuel trims and see if the problem goes away. If gone with the O2 sensors disconnected, then swap the sensors side to side and see if the problem follows the O2 sensor. If it is not an issue with that cat than I am almost positive you have a weakened fuel pump which is actually EXTREMELY common. I wish I could tell you how many people say well it has fuel so I dont believe you, but when I connect a fuel pressure gauge it is not within spec, come to find out the electronic pump is just not performing like it should. I believe autozone will rent the fuel pressure tester free but if not they run about 20 bucks. With your vehicle it will fit it right out of the package without an adapter. Just look under the hood follow the fuel rail to a little cap like a tire gauge but bigger this is the port. The pressure needs to be EXACT or within 1-2 PSI because gauge could be off. These are extremely sensitive Check the fuel pressure during the lack of power. At wide open throttle, the fuel pressure should be at or near 63 PSI. If not, verify the filter is clean. Verify the good power and ground to the pump assembly. If pressure is still low during the problem, replace the fuel pump. This in my professional option is what I would do. Most of the time no CEL will ever be present when it is the fuel pump usually it is when it is related to the ignition system.
Not a problem, if you need anything just let me know. If you wouldnt mind accepting or rating I would appreciate it. You can always still reply if needed.