My mods are in the sig below.. I have a low mile (11k) LT1 Z that runs great but has set this code a couple times now. It has run great all along but after a couple days of freeway driving (10-15) it sets this code. It still runs great but the light is annoying. I reset the code and drove it on back roads, city streets etc. With no problem... but today again at almost the same place on the freeway it tripped again. The EGR was replaced when the headers/cam/heads were installed. Anyone else had a similar issue with this code? I know it can be "tuned" out but have been having trouble finding anyone local that can do it. Thanks

 

I didn't know any long tubes had emissions connections for the EGR.

 

My Kooks have air and egr both.

 

When you replaced the EGR valve with the new headers, did you get a valve specifically for low back-pressure? Somewhere in the back of my mind, in the course of reading 10's of thousands of posts here, I recall that as being the solution with exhaust systems with headers and no cats.

The diagnostic only runs once per trip, and can only run under very specific, stable operating condition - throttle position, MAP reading and no change to TPS of more than 1% over a 1 - 2 second period.

I also recall several people using the EGR vacuum solenoid circuit to insert a specific resistance in the MAP sensor signal wire, to spoof the change in MAP (greater than 1kPa) that the PCM diagnostic is looking for when the EGR valve is closed.

 

The shop manual says the PCM looks for a change in MAP when it runs the test. Although I never seen a bad MAP sensor, is it possible it has some issue?

 

Since this only trips the code in a specific set if circumstances, freeway cruise, light steady throttle, over 85 degrees (it didn't set the code on the same trip to work in the much cooler AM). It is still the OEM EGR, do you think a low back pressure specific EGR would solve the issue or do I just have a bad EGR? Thanks for the input guys.

 

It could be the low back pressure in your exhaust system, or it could be anything that prevents the exhaust gas from flowing:

Vacuum line(s) loose or broken

EGR Vacuum solenoid not opening (would have to be a mechanical problem. An electrical problem would set P0403)

EGR valve faulty

EGR pintle plugged with carbon

Riser tube from #8 primary cracked or loose

To check the vacuum/solenoid related items, with the engine idling, provide a ground to the EGR vacuum solenoid (gray wire). If the engine runs rough or stalls, the vacuum connections, the solenoid and the EGR are fine.

 

I'm running Kooks with EGR and AIR. I've got the dual cat y-pipe and a flowmaster 17133 system(catback with 80 series muffler).

I've had no codes with the EGR system and they are enabled.

Do you have cats?

 

I have the exact same set up you do except I have a Corsa catback. I'm thinking it's the EGR is bad or the stock EGR is operating outside the stock parameters (lower back pressure) but don't want to change out to a new EGR and have it trip the same code again. My Corsa is pretty loud and pops some while decelerating in gear. How loud is your Flowmaster and does it pop too? Maybe your catback is a little higher back pressure.... just guessing.

 

When revving it cold, it will pop just a little, after it's warmed up it does not pop and revs cleanly.

 

Where would I find a "low back pressure" EGR?? Thanks to all of you that have contributed the input.