sc.schultz

iTrader: (2)

I have a stock 97 SS LT1 that is throwing the following codes:

P0400 - Exhaust Gas Recirculation Flow Malfunction
P0403 - Exhaust Gas Recirculation Circuit Malfunction
P0443 - Evaporative Emission Control System Purge Control Valve Circuit

So far I have replaced the EGR valve and purge solenoid with no luck... Any ideas as to what this could be? I plan on getting headers/ory/tune soon, but until then I would like to get this resolved.

Thanks

sc.schultz

iTrader: (2)

Update: I just replaced the EVAP purge solenoid as well. Also, when I push in the EGR on the back of the intake, the engine stumbles/feels like its going to stall. So the intake passages aren't clogged.

Anyone have any clues?

sc.schultz

iTrader: (2)

I just replaced the EGR gasket thinking maybe the old one was leaking. Same problem. When I clear the codes, they come back after about 6 miles of driving (once my engine warms up). Has anyone had this problem, if so, how did you fix it?

It will actually throw 7 codes, a few of which are the same:

p0403
p0400
p0443
p0400
p0403
p0441
p0443

After removing the duplicate codes, this is what I'm left with:

P0400 - Exhaust Gas Recirculation Flow Malfunction
Plugged EGR passage which restricts the flow of exhaust gasses
Faulty EGR solenoid
Faulty EGR solenoid wiring/harness
Vacuum lines damaged/disconnected to the EGR valve solenoid or to the EGR valve
Faulty EGR valve
P0403 - Exhaust Gas Recirculation Circuit Malfunction
Bad EGR solenoid
Excessive resistance in control circuit (PCM controlled ground) due to an open, chafing or damage to the harness
Poor connection at the EGR solenoid harness (worn or loose pins)
Water intrusion at the EGR solenoid harness
Blockage in EGR control solenoid holding solenoid open or closed causing excessive resistance
Loss of supply voltage to EGR solenoid
Bad PCM
P0441 - Evaporative Emission Control System Incorrect Purge Flow
Bad vacuum switch
Broken or damaged EVAP line or canister
Open in PCM purge command circuit
Open or short in Voltage feed circuit to Purge Solenoid
Faulty purge solenoid
Restriction in EVAP solenoid, line or canister
Corrosion or resistance in purge connector
Bad PCM
P0443 - Evaporative Emission Control System Purge Control Valve Circuit
Bad purge solenoid (internal short or open)
Wiring harness chafing or rubbing another component causing short or open on control circuit
Connector worn, broken or shorted due to water intrusion
Driver circuit inside powertrain control module (PCM) is bad

luigiandme

iTrader: (2)

Check the fuse for the EGR Solenoid... Its in the Underhood Fuse Block. Fuse #2 15A Labeled ACTUATORS.

sc.schultz

iTrader: (2)

I was hoping that would be it... but I just checked and the fuse is fine.

SS#502

Sounds like a vacuum leak, are all your hoses and fittings good on all your emissions?

sc.schultz

iTrader: (2)

They look fine and I've checked most of them. I'll buy a vacuum gauge tomorrow and test it out.

EDIT:

For anyone with the same problem, this is what it boiled down to being for me:
https://ls1tech.com/forums/lt1-lt4-m...plug-into.html