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Joined: Aug 2002
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Hard-core CEG\'er
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Hard-core CEG\'er
Joined: Aug 2002
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I tried searching "personal facial vac", "personal facial vacuum", and various other combinations in both the new boards and archives with no luck. Can someone point me to this thread that gives instructions on how to vacuum test the EGR? My car just threw a P0401 code and I'm trying to figure out the source of the problem. Thanks.
Chris G.
~ 98 Mystique LS ATX
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Joined: Aug 2002
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Hard-core CEG\'er
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I found the thread; however, I'm still confused about what each effect (of sucking/crimping the vacuum hose) means.
Can someone clarify the various causes/effects for me?
Thank you.
Chris G.
~ 98 Mystique LS ATX
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Hard-core CEG\'er
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The applied vacuum pulls against a diaphram in the EGR valve and mechanically pulls a pintle out of its seat allowing EGR gasses to flow through the valve. When vacuum is released, the spring-loaded pintle returns to its seat and seals off the flow of EGR gasses.
EGR flow should occur only under the control of the PCM when driving conditions are such that EGR flow will lower combustion temps and keep NOx emissions down. The PCM does this by applying variable duty cycle power to the EVR (EGR Vacuum Regulator) solenoid. Depending on the duty cycle, a varying amount of vacuum will be switched through by the EVR solenoid to the EGR valve allowing control of the amount of EGR flow.
The computer uses the DPFE sensor to measure the amount of EGR flow by measuring the difference in pressure across an orifice that is exposed to the EGR flow. The greater the rate of flow, the greater the difference between the two ports of the sensor. The computer uses this feedback to achieve the desired amount of EGR flow.
If the ports in the throttle body clog (most common reason), the EGR valve will be opened fully but the DPFE sensor cannot sense any or sufficient flow. The PCM sees this and sets the P0401 fault code.
The other common failure is the DPFE sensor. It cannot measure the actual flow and sets the same code.
The purpose of applying vacuum to the EGR valve during idle is to see if the EGR valve will open and allow EGR gasses to pass all the way to the intake. This is indicated by the stalling or stumbling when the EGR valve is opened on a properly functioning system.
Steve
98 Contour SE Sport 2.5 Duratec ATX The wifey's car
89 Taurus SHO - 246K miles
94 SHO ATX - 190K
1997 F-150 5.4L ATX - The Workhorse 150K.
ANY THREAD WITH "OMG" or "WTF" ETC IN THE TITLE WILL BE IGNORED!
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Joined: Dec 2001
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Hard-core CEG'er
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Hard-core CEG'er
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for the most part
P0401 - tb passages need cleaning
P0402 - DPFE sensor is bad and needs to be replaced, make sure you get the revised plastic one also
- 95 Mystique LS - Zetec/5spd
- 99 Contour SeVT Sport - Duratec/5spd
Official NE-CEG Contour/Mustang Family
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Originally posted by BrApple:
for the most part
P0401 - tb passages need cleaning
P0402 - DPFE sensor is bad and needs to be replaced, make sure you get the revised plastic one also
It's not that simple.
A P0401 could be a number of things, the most common would be the TB ports. It an also be the DPFE sensor.
A P0402 could also be a number of things of which the DPFE sensor is only one.
In each case, additional troubleshooting is recommended. Failure to do so will greatly increase the odds that you will waste either time or money.
Steve
98 Contour SE Sport 2.5 Duratec ATX The wifey's car
89 Taurus SHO - 246K miles
94 SHO ATX - 190K
1997 F-150 5.4L ATX - The Workhorse 150K.
ANY THREAD WITH "OMG" or "WTF" ETC IN THE TITLE WILL BE IGNORED!
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