Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
So there are no codes at this time?
Does fuel pressure hold steady?
Any air or vacuum leaks?
Sounds like plugged exhaust. The easiest way to check for this is to hook up a vacuum gage to any vacuum source from the intake manifold. It should read about 17 to 19 inches of steady vacuum at idle. Upon snapping the throttle quickly to about 3000 rpm and letting off back to idle, you should see the vacuum gage go from steady 18 inches of vacuum to 0, back past 18 inches of vacuum, to about 23 or 24 inches of vacuum back to about 18. If it does not go back past 18 inches to 23 or 24 before returning to 18 something in the exhaust is definitely plugged up.
Or you can always pull the o2 sensors and see if it makes any difference. :)
CIRCUIT DESCRIPTION The powertrain control module (PCM) electrically erasable programmable read only memory (EEPROM) contains data which is essential for operating the engine and the transmission. The PCM continuously tests the integrity of this data.
CONDITIONS FOR RUNNING THE DTC The ignition switch is in the crank position or in the run position.
CONDITIONS FOR SETTING THE DTC The PCM is unable to correctly read the data from the flash memory.
ACTION TAKEN WHEN THE DTC SETS
The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.CONDITIONS FOR CLEARING THE MIL/DTC
The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. A current DTC, Last Test Failed, clears when the diagnostic runs and passes. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. Clear the MIL and the DTC with a scan tool.DIAGNOSTIC AIDS
IMPORTANT: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.
Replace the PCM even if this diagnostic trouble code (DTC) exists only in history
Thanks for the accept!