Quote:
Originally Posted by tasdrouille
As Christ pointed out, the MAP sensor will not sense it. I removed this part from my post.
EGR works as long as the pressure in the exhaust manifold is higher than the pressure inside the intake manifold. It is possible to have significant EGR levels at WOT and even at positive intake manifold pressure. In fact, diesel engines always operate EGR with positive intake pressure.
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I'm not understanding why this is. I'm cruising along at part throttle, so I have vacuum in the intake manifold. Then, I open up the EGR valve a bit. This is going to reduce the vacuum. The MAP sensor should see that.
At full throttle I could definitely imagine seeing positive pressure in the manifold, but I don't see that happening any other time than that. I guess I was also under the assumption that exhaust pressure was always higher than intake pressure as well.