have a 97 z, jet hot long tube headers, hooker catless y-pipe, borla catback,,my egr system keeps throwing a code p0400, my dad hooked up his scanner to it, and it just says egr system,, he said i don't have enough back pressure to open up my egr system,,has anyone else ever had or heard of this problem?

 

Yes.... good analysis. EGR is a problem on many OBD-II cars with low back pressure exhausts.

 

The sealing materials used in the EGR valves in 97 were defective. There is a TSB out on it. GM has a new revised valve now. My 97 was throwing the 0400 code too and I didnt have headers. I replaced the valve with the new valve two years ago and the code has been gone since. My old valve was leaking so bad you could smell the fumes under the hood.

 

well, i put on a new egr valve, cleared the code, and then it came back on, i found a hose that cam off the purge selinoid,,cleared the code again,,,and the light is back on? my dad suggested porting the erg vlave a bit to help assist it opening,,???
thanks for the replies
-Jason

 

You need to make an EGR simulator like I did...it is the only way to prevent the P0400 code unless you have your EGR programmed out of your PCM.

 

Had the same problem with my 97 as well. It appeared that the EGR was good when I would test it. However, it kept throwing a P0400 like yours when I would hit 6th gear at low speeds (low vacuum). Replaced the valve with a new one, everything works fine... and no more codes. Good luck... you may have to program it out like many do when they have headers and/or exhaust.

 

This is true, but 96-97 cars with long tubes will most likely throw this code due to the exhaust pulses going from 4 to 1 going to the EGR. Make a simulator...it works.