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Discussion Starter #1
where do I start with this one. My car has had a little bit of a rough idle. I have a 94 4.6 is there any easy way of changin this valve or what should I check first
 

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99.999% gaurentee it's your Differential Pressure Feedback EGR (DPFE) sensor. This sensor detects the difference in pressure between two sample tubes that connect to the main EGR feed tube. The sensor can not be cleaned, only replaced. Clear the code if you can and see if it comes back. If it does come back, the sensor will need to be replaced ... cost about $60-$80 and is very easy to do.
 

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Discussion Starter #4
how do I know that its this sensor and not the egr valve itself. Is there anyway of checking it. The egr valve itself is a pain in the *** it looks like to remove. I have a 94 where is this sensor and would having a bad sensor possible cause my slight rough idle. I have had the rough idle for a while now and when the check engine light finally came on I figured it could be the problem. I did drive the car for about 4 hours on the highway with no problems. I think that the car is running a little rich Im not getting the best gas mileage and the mufflers drip some water. I don't know if that is normal.
 

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Discussion Starter #5
the code that was thrown was P0402 I believe that the code description is excessive egr flow. Thanks for any help
 

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attach a small draw tube to the vacuum nipple and "suck" ... something should happen (internal diaphram opens/closes). If nothing happens, the valve is broken. Again, I highly doubt the valve is the cause ... could be, but doubt it. I have had this happen on all three Ford that I have owned! Each time it has been the DPFE sensor.
 

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Discussion Starter #9
would this sensor cause the car to act up. I have a little bit of a rough idle could that be the cause of it
 

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Like MyCarMods says

Just to further back up what he says the action of the valve when suction is applied is better observed when it has been removed. You can watch the valve move up and down which means you can see if it sticks or not. (the valve stem can get coked up)

Hope this helps

Chris...............

MyCarMods said:
EGR isn't supposed to be open during idle, only during partial load situations, so
yes, it would cause a funky idle is stuck in the open position.
 

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Discussion Starter #12
its a pain in the *** to remove the egr valve on the 94 though. Some guy told me you have to take off the whole intake. Or is there an easier way of doing it
 

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Discussion Starter #13
i tried the vacuum line suck trick that you said and it sounded like the valve was opening when i sucked. I also reset the computer and the code hasn't come back its been about 2 days and the light hasn't come back on. what should I do. Would a bad sensor cause the rough idle or would it just be a bad egr.
 
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