i cut my cats off and i started getting the egr flow malfunction code po400 and i would have to clear this code once a week so i said what the heck and bought an egr valve and i still keep getting this code is this because i cut off my cats??

 

Well you will get a code, not sure which one, but you will get one if you remove the cats on a dual cat car. There are an extra set of O2 sensors on dual cat cars, and those measure how the cats are working. You'll get a code if the cats arn't there.

 

yes...mine does the same thing while on the highway...i can almost predict when it will come on...after cruising at a steady speed (~60-65) in 6th gear. i was warned before i took my cats off so i was expecting it.

 

I'm getting the same problem on my 97 z28. I took out my cats and installed some o2 simulators but the SES keeps coming on every few days when cruising. Let me know if you find a way to fix this.

 

Your O2 simms will take care of oxygen sensors, but won't do anything for the EGR trouble code. I had the same problem when I went with headers and an off-road y-pipe setup. I had the EGR reprogrammed out of the PCM by Madwolf. No problems with the SES since.

 

is the ses on? what happens when u gotta get smogged?

 

You won't pass. You wouldn't pass anyway if you didn't have cats.

As far as the EGR problem, it's pretty common with OBDII. I had the same problem and just ended up putting the cats back on, the cats FLP provides are high flow anyway. The only other solutions are either get the EGR programmed out or make one of those EGR sims I read about in a past thread.

 

i dont think they hook the obd 2s up to smogg anymore except maybe in cali., then again im not sure. they did here a few years ago, but when they switched how they inspected the obd2 cars, they no longer do the smog test on them. all they do is connect to your cars computer to read any codes basically. so as long as your computer thinks its running clean, the inspection computer will read that it is ok. at least that is the way i understand it.

 

The EGR code is triggered because you don't have enough back pressure to allow the EGR system to function correctly. It's common for this code to show up when the exhaust has been modified significantly. The only way to keep it out, is to program it out. I got the code intermittently after just putting a cat-back on.

 

crazy thing actually happened. i mentioned it in another thread but i mention it again here. this whole time i had an exhaust cutout right before my muffler so pretty much I was running w/ no muffler. I closed the cutout and the SES went away that night. Musta been the back pressure thing you talked about. =)

 

Can anyone verify what walkovaya is saying bout the obd2 and smog?

 

i know for a fact that is how it is in NC (no smog on the obd2 cars), i work at a dealership. i just dont know if it is that way in all the states mainly California (since they are so strict.)

 

Well I passed smog w/ a cutout wide open right before my muffler so who knows w/ the cats