Hey guys I've tried searching but havent come up with anything that sounds like the problem I'm having. For the past month my car has been missfiring really bad. You can hear it at idle and when you accelerate normally it will run smooth until you shift, then it will stutter for a second then run smooth until you shift again. Anytime I go WOT it will miss right away and continue to stutter all the way through the rpm's...I usually can't even get to redline. My mods are GM stage 2 with a 2.9 inch pulley, intake, and full exhaust. My intake is just a cone filter on the stock piping though. It was that way when I bought it and I had no problems until that filter fell off and I found that it was in bad condition so I bought a new one. It was just a day or two after that i started experiencing the problem. I have cleaned the MAF several times, as well as the throttle body, supercharger inlet, and MAP sensor. The olny code I have thrown was the P0171. I was thinking maybe the filter was too free-flowing causing the MAF to read wrong so I tried restricting it down but to no avail. If anyone has any thoughts or ideas any insight would be greatly appreciated. Thanks guys

 

Heres some stuff to check

1)Operate the engine at idle.
Observe the Heated Oxygen Sensor (HO2S) parameters with a scan tool.

2)Visually and physically inspect the following items:
The vacuum hoses for splits, kinks, and proper connections

3)Inspect for the following conditions:
The HO2S for proper installation
Ensure that the electrical connectors and wires are secured and not contacting the exhaust system.

4)Inspect for the following conditions:
-Missing, loose, or leaking exhaust components
-Vacuum leaks at the intake manifold, throttle body, and injector O-rings
-The air induction system and air intake ducts for leaks
-The crankcase ventilation system for leaks
-The evaporative canister purge pipes for obstructions or plugging.

5)Still could be your Maf
Observe the manifold absolute pressure (MAP) sensor pressure parameter with a scan tool.

Worst case
6)If conditions were not corrected, a worn cam, worn intake or exhaust valves, or other engine mechanical failure may be at fault.

7)Test for fuel contamination. Small amounts of water can be delivered to the fuel injectors and cause a lean exhaust indication. A lean exhaust indication can also be caused by too much alcohol in the fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

8)The system will go lean if an injector is not supplying enough fuel.

9)A lean condition could be present during high fuel demand due to a fuel pump that does not pump enough fuel, a plugged fuel filter, or a restricted fuel pipe.