L67 Code P4201
#11
DINOSAURUS BOOSTUS
Expert Gearhead
Let me step in here for a moment. I've got a good amount of experience with that item in the picture, vacuum tubes and the code in question.
First, the picture is exactly as Dan mentions. The boost control soleniod and that'* a purge/vent opening that only ever gets a little foam filter over it.
Vacuum lines, fix them up now. There'* no reason not to have your car running tip top over a few low cost rubber hoses.
The insufficient flow code. Yes the letters EGR are in the title. Let'* stop and think a moment, you mention a crack in the tube. How is a vacuum leak insufficient flow? It would be excessive flow. Now that we've gotten that settled...we need to understand how the pcm monitors "flow". Flow is determined by the change in map pressure that the pcm sees on the map sensor. Right.. if the map sensor is not seeing the change in pressure the pcm says.. "hey.. the EGR didn't make enough of a change in the map reading when I told it to open". This doesn't mean the EGR is bad or broken. This means there wasn't enough of a change. Tons of large vacuum leaks can keep that from occurring as there would be a lot of flow all the time. A bad map sensor can be having trouble sensing the change and lastly..the EGR might not be opening.
Let'* dive deeper into this one. You aren't getting a code for incorrect pintle position or electrical etc on the EGR. Those in addition to this code would point us more toward a bad EGR. We aren't seeing that though.
I'd start right where Dan suggests with the vacuum tubes, clear the code. I'm thinking there'* a good chance the vacuum T under the charger snout (that feeds the map sensor) is one of the vacuum leak pieces.
First, the picture is exactly as Dan mentions. The boost control soleniod and that'* a purge/vent opening that only ever gets a little foam filter over it.
Vacuum lines, fix them up now. There'* no reason not to have your car running tip top over a few low cost rubber hoses.
The insufficient flow code. Yes the letters EGR are in the title. Let'* stop and think a moment, you mention a crack in the tube. How is a vacuum leak insufficient flow? It would be excessive flow. Now that we've gotten that settled...we need to understand how the pcm monitors "flow". Flow is determined by the change in map pressure that the pcm sees on the map sensor. Right.. if the map sensor is not seeing the change in pressure the pcm says.. "hey.. the EGR didn't make enough of a change in the map reading when I told it to open". This doesn't mean the EGR is bad or broken. This means there wasn't enough of a change. Tons of large vacuum leaks can keep that from occurring as there would be a lot of flow all the time. A bad map sensor can be having trouble sensing the change and lastly..the EGR might not be opening.
Let'* dive deeper into this one. You aren't getting a code for incorrect pintle position or electrical etc on the EGR. Those in addition to this code would point us more toward a bad EGR. We aren't seeing that though.
I'd start right where Dan suggests with the vacuum tubes, clear the code. I'm thinking there'* a good chance the vacuum T under the charger snout (that feeds the map sensor) is one of the vacuum leak pieces.
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DJ SHO
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07-19-2004 03:39 PM