Rough idle at lights ~ EGR valve code

I have a 1999 Silverado Z71. Lately when I reach a stop light I've noticed the truck idling a little hard. Also, its getting worse. Now when i'm idling, the lights dim and the engine nearly stalls, then revs again, then seems to stall again. After about 10 min of driving once the engine gets up to speed, things seem to work just fine again. I got some of the following codes:

P0405 Exhaust gas recirculation sensor circuit low

P0440 Evaporative emission control system malfunction

P0449 Evaporativ emission contril sstem, vent control circuit malfunction

P1404 EGR valve closed pintle position

I'm tempted to just replace the whole dang EGR valve dealy but they run upwards of $150 and that sux. Is it the EGR valve thats crapped out? Should I replace it? Any thoughts would be helpful.

Aight.... well I replaced the EGR valve. Its pretty simple, just two bolts and the thing is on the front passenger side of the engine so its really easy to get to. $128 later and the problem is 95% fixed. The truck still does a tiny little rumble sometimes when its idling but i feel that its completely unrelated to the EGR vavle.

Well, I seem to be talkin to myself but feel free to chime in.

Truck was running well for the last two days since I replaced the EGR valve. All the sudden, the truck starts to shudder at the stop lights again. Not when I slow down, but when its stopped. It'd idling weird. What next?

Having same issue with 99 Grand am. Similiar Codes as well (P0440, P0405, & P0403. Had to replace infamous leaking intake manifold gasket 2 weeks ago, and seems to be where problems started. (Not sure however). Did notice loose vacuum line (after finally finding hiss from manifold leak) to EVAP Solenoid Purge Valve. Plugged line back in solenoid, and car immediatly stalled. Not sure how to test if solenoid is bad, but mine is only a $25.00 part from NAPA. May give it a try to see if it works.

I have a 1999 Silverado Z71. Lately when I reach a stop light I've noticed the truck idling a little hard. Also, its getting worse. Now when i'm idling, the lights dim and the engine nearly stalls, then revs again, then seems to stall again. After about 10 min of driving once the engine gets up to speed, things seem to work just fine again. I got some of the following codes:

P0405 Exhaust gas recirculation sensor circuit low

P0440 Evaporative emission control system malfunction

P0449 Evaporativ emission contril sstem, vent control circuit malfunction

P1404 EGR valve closed pintle position

I'm tempted to just replace the whole dang EGR valve dealy but they run upwards of $150 and that sux. Is it the EGR valve thats crapped out? Should I replace it? Any thoughts would be helpful.


I hope this helps:
As for your code P0405, cleaning it may have helped, but this code is usually an electrical problem inside the valve. By you removing the valve and banging it around, you may have unintentionally caused the sensor to work again, for how long, who knows.
Here’s a bit on this circuit, a little long but worth the read.
Dan.

Circuit Description
An Exhaust Gas Recirculation (EGR) system is used in order to lower Oxides of Nitrogen (NOx) emission levels. The EGR system accomplishes this by recirculating small amounts of exhaust gas back into the combustion chamber. High combustion temperatures cause NOx. Combustion temperatures are reduced when the air/fuel mixture is diluted with the exhaust gases.
The EGR valve is designed to accurately supply exhaust gases to the engine without the use of intake manifold vacuum. The EGR valve controls the exhaust flow into the intake manifold from the exhaust manifold through an orifice with a PCM controlled pintle. The PCM controls the pintle position using inputs from the Throttle Position (TP) sensor, the Manifold Absolute Pressure (MAP) sensor and, the Engine Coolant Temperature (ECT) sensor. The PCM commands the EGR valve in order to supply the correct amount of exhaust gas recirculation for the current engine operating conditions. This can be monitored on a scan tool as the Desired EGR Position.
The PCM monitors the position of the EGR valve through a feedback signal. The PCM supplies a 5.0 volt reference circuit and a ground circuit to the EGR valve. A voltage signal representing the EGR valve pintle position is sent to the PCM from the EGR valve. This feedback signal can also be monitored on a scan tool and is the actual position of the EGR pintle. The Actual EGR Position should be near the Desired EGR Position.
Conditions for Running the DTC
The ignition voltage is greater than 11.7 volts.
Conditions for Setting the DTC
 The EGR feedback signal voltage is less than 0.14 volts.
 All conditions present for 0.1 seconds.
Action Taken When the DTC Sets
 The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
 The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
 The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
 A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
 A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
 Use a scan tool in order to clear the MIL and the DTC.
Diagnostic Aids
Important
Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.
Due to the moisture associated with exhaust systems, the EGR valve may freeze and stick in colder weather. After the vehicle is brought into a warm shop for repairs, the valve warms and the problem disappears. By watching the Actual EGR Position and the Desired EGR Position on a cold engine with a scan tool, the fault can be verified easily. View the freeze frame data to determine if the DTC set when the vehicle was cold by viewing the Engine Coolant Temperature (ECT).

P0440: Gas cap may not be on tight or a hole in the line, bad sensor, purge valve, or vapor canister

P0449 says that the PCM is not seeing the voltage potential it wants to see when the vent valve is off or commanded on. Could be the solenoid, wiring or the PCM itself. PCM would be my very last choice, but it remains a possibility.

Do you have power at the pink wire of the vent solenoid connector when the key is on? If so, that leaves the control circuit as the suspect. You may have an open somewhere in that wire from the solenoid to the PCM. Or it could be right at one of the terminals in the connector at the vent valve or at the PCM. There's also an inline connector that's under the UBEC (underhood fuse box).


I hope this helps you