This is probably more for John, but on my 96 Vette, I've been getting a P0400 code - EGR.
I've taken the EGR valve off to see if it had carbon build up but it was actually in good shape. I still cleaned what I could and re-installed it. I drove the car for ~10 minutes and the SES (service engine soon) light came back on.
I don't think it's the solenoid because the SES light would have come back on as soon as I started the car (according to what I read on another forum):
the computer will sence a bad control valve during initial self test at startup, but it won't find the EGR until it goes into closed loop
eGoCeNTRoNiX wrote:Make sure there are no leaks where it connects to the intake. On my car the o-ring can go bad/has gone bad causing it to throw the EGR codes.
Good Luck!
eGo
No o-ring. Only a paper/metal type gasket which I replaced when taking it off. Here is what it looks like:
On my car, it's the tube going into the intake that gets clogged up. Every 5 years or so, I have to buy about 1' of 3/8" steel braid cable and hook it up to a drill. I then fray the end a bit and ream the hole out. I believe that running it in reverse will keep it from unraveling on you, but it's been a while.
What Norm said... I'd check the hose going from the valve to the intake.. Easy enough, just unhook it and try to blow through it.. No blow = clogged hose.. haha
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Fixed! I guess I did not take it all the way apart. After I removed the seat from the main body, I saw the culprit: the small orfice hole that was plugged as shown in this pic: The thin white wire is inserted into the EGR’s pintle exhaust back pressure drilled orifice. This tiny orifice allows exhaust back pressure to react with intake manifold vacuum to control EGR flow. This small port can become plugged and the EGR will hang open.
After I cleaned it with a brass brush and sprayed some brake cleaner, I drove it for 15 minutes and the light remained off. Good article here that discusses the technical operation of the EGR. http://tech.corvettecentral.com/2012/11 ... diagnosis/
