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andykrow,Have you pulled the spark plugs to see how the mixture is firing?
I really need a vacuum diagram for this thing....
I am having a hard time believing a malfunctioning EGR is causing the crazy spike I was seeing in NOx. Sure, EGR will reduce Nox but that much? I have known CO trucks to get through emissions with EGR disabled so I don't think that is my main issue. Sure, EGR could get me through but that may just be a bandaid.
@emsvitil Thinking more about that baffle, have you tested with and without? I do not understand why the EGR would need back pressure. It seems like once the valve opens manifold vacuum would suck the exhaust right in, pressure or not. Or is there some sort of exhaust scavenging at work? (Bernoulli's principle?)
I actually had it stock for the first test, 5 degrees BTDC with the test connector in. For this one I put it to zero, so less advance compared to stock. Should help lower NOx. After this test I got a little more HC, but it is still really low. I might go another click rich in the afm. Actually these emissions test are kinda like a cheap dyno pull. Sorta helping me tune the thing. Or that's what I am telling myself so I don't get raging pissed off.
Ok, scroll up.Snowtoy already posted picture of EGR with modular. The backpressure helps the modulator............It closes off the 'T' that has a vacuum escape at the bottom.
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