Quote:
Originally Posted by BonzoHansen
Jon, IIRC, he failed inspection for high NOX. I thought he said he had a new EGR valve, but I wondered if it might have a bad EGR solenoid or other related part, or a coked up intake. I don’t know these setups at all or common failure points, so I'm going by what I've seen in the earlier ones. Thoughts?
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OK, didn't realize he was actually failing that badly.
Normally the EGRs go bad they stick open a bit, which noramlly doesn't throw a code. But more often they aren't closing because of build up then from having gone bad. You can sometimes feel the car "stumbel" at cruising speeds 35-45 MPH, or if you lightly power brake the car, and it stumbles the EGR is not closing all the way.
So having a clogged ERG track is actually more common then a bad EGR, it's a common failure point for emmisions. Because the LT1s pulled right from the exhaust header, as the engine gets older it builds up crap in the intake, plus if it starts to burn a little oil it gets pulled into the intake and baked into the manifold.
Dealer wanted some outragious price to remove and clean the intake. We've been able to fix it many times with a treatment of Seafoam, then replacing the plugs and O2s. instead of pulling the intake.