Fuel System (despite new parts):
* Fuel pressure regulator: A faulty regulator might not maintain the correct fuel pressure, leading to hesitation. While you've replaced the filter, the regulator itself could be malfunctioning.
* Fuel injector o-rings or seals: New injectors don't guarantee perfect seals. Leaks around the injectors can cause inconsistent fuel delivery.
* Clogged fuel lines: Debris might still be present in the lines despite the new filter.
* Faulty fuel pump (despite new filter): The pump itself could be weakening, unable to deliver sufficient pressure at higher RPMs. A new filter won't solve a failing pump.
Ignition System:
* Worn spark plug wires: These can cause misfires, leading to hesitation.
* Faulty ignition coil(s): A weak or failing coil can prevent proper spark delivery to one or more cylinders.
* Distributor cap and rotor: These components can wear, causing poor spark distribution. Carbon tracking inside the cap is a common problem.
* Ignition control module (ICM): This module controls the ignition system; a malfunction can disrupt spark delivery.
* Crankshaft Position Sensor (CKP) or Cam Position Sensor (CMP): These sensors tell the computer the engine's position, influencing fuel injection and spark timing. A faulty sensor can lead to hesitation or misfires.
Other Potential Issues:
* Mass Airflow Sensor (MAF): A dirty or faulty MAF sensor provides inaccurate air readings to the computer, leading to incorrect fuel delivery.
* Throttle Position Sensor (TPS): A malfunctioning TPS provides inaccurate throttle position information, affecting fuel and ignition timing.
* Intake air leaks: Leaks in the intake system can create a lean fuel mixture, causing hesitation and rough running.
* EGR valve: The Exhaust Gas Recirculation valve, if stuck open or closed, can impact engine performance.
* Vacuum leaks: Small vacuum leaks can significantly affect engine performance and cause hesitation.
* Computer/ECM issues: While less likely, a problem with the engine control module (ECM) could be causing the issue.
Troubleshooting Steps:
1. Check fuel pressure: This should be done at idle and under load (while accelerating). A pressure gauge is necessary.
2. Inspect spark plugs and wires: Look for wear, fouling, or cracks.
3. Test the ignition coil(s): A specialized tester or visual inspection for cracks might be needed.
4. Clean or replace the MAF sensor: This is a relatively inexpensive and easy test.
5. Check for vacuum leaks: Use a vacuum gauge or listen for hissing sounds around the intake manifold.
6. Inspect the distributor cap and rotor: Look for any carbon tracking or damage.
7. Have the car scanned for diagnostic trouble codes (DTCs): A scan tool can identify potential problems within the engine's electronic systems.
It's important to systematically test these components. Starting with the simpler and cheaper checks (like inspecting the spark plugs and wires) before moving to more involved diagnostics (like replacing sensors) is recommended. If you're not comfortable working on the car yourself, taking it to a qualified mechanic specializing in Corvettes is a wise decision. They have the experience and tools to diagnose the problem accurately.
