I have gone through so many threads to try to figure this out.
Replaced EGR Valve (new OEM part came with truck) and VSV. Modulator tests fine. Still getting P0401 (Insufficient Exhaust Gas Flow). According to the EGR System Test in the FSM I T'd between the Modulator and the EGR valve, and hooked into a mighty vac. I should get low vacuum with warm engine @ 2500 RPM. I GET ZERO. The FSM doesn't give IF this, then THAT scenarios. What does it mean? Clogged ports or vacuum lines? If so, which ones should I check? BTW, I checked the flow of the "P" and "R" lines going into the throttle body. Not great, but there is some flow. Also, replaced the lines. What other lines, if any, should I check? How can you tell if ports in intake or TB are blocked? Do you have to take them off or just throttle body? I have not messed with the temp sender since many say that is not likely problem. However, could that be the reason why I am not getting any vacuum as described above? How do you test it?
Other Questions:
FSM says to connect port "R" on modulator directly to the intake manifold. Anybody know exactly where on the intake manifold that should be?
Correct me if I'm wrong: The VSV turns vacuum on/off by opening or closing to atmosphere. Modulator controls the amount of vacuum applied to EGR valve which in turn opens up the spigot for the hot exhaust gases. Can anyone give me an explanation of the DIRECTION of flow of the system? I believe the vacuum comes from the engine sucking in air - more RPM, higher vacuum. But, where is the line that provides it, the "P" and "R" lines? Why two of them?
After I deal with this, I have to figure out why the CAT doesn't go into a Ready State.
Help,
help...I'm sinking
Replaced EGR Valve (new OEM part came with truck) and VSV. Modulator tests fine. Still getting P0401 (Insufficient Exhaust Gas Flow). According to the EGR System Test in the FSM I T'd between the Modulator and the EGR valve, and hooked into a mighty vac. I should get low vacuum with warm engine @ 2500 RPM. I GET ZERO. The FSM doesn't give IF this, then THAT scenarios. What does it mean? Clogged ports or vacuum lines? If so, which ones should I check? BTW, I checked the flow of the "P" and "R" lines going into the throttle body. Not great, but there is some flow. Also, replaced the lines. What other lines, if any, should I check? How can you tell if ports in intake or TB are blocked? Do you have to take them off or just throttle body? I have not messed with the temp sender since many say that is not likely problem. However, could that be the reason why I am not getting any vacuum as described above? How do you test it?
Other Questions:
FSM says to connect port "R" on modulator directly to the intake manifold. Anybody know exactly where on the intake manifold that should be?
Correct me if I'm wrong: The VSV turns vacuum on/off by opening or closing to atmosphere. Modulator controls the amount of vacuum applied to EGR valve which in turn opens up the spigot for the hot exhaust gases. Can anyone give me an explanation of the DIRECTION of flow of the system? I believe the vacuum comes from the engine sucking in air - more RPM, higher vacuum. But, where is the line that provides it, the "P" and "R" lines? Why two of them?
After I deal with this, I have to figure out why the CAT doesn't go into a Ready State.
Help,
help...I'm sinking