I have a 98 F-150 4.6, Ive replaced the egr valve, and the map sensor on it and its still throwing up code P0402 excessive EGR flow is what its saying when its pluged in. The only thing I have done to my truck engine wise is a volant cold air and a granitelli mass air sensor. At one point I thought I remember someone saying at the shop there is a sensor in the back of the intake that has to do with the egr but I dont really remember though.

 

did you reset the codes after the repairs???

 

Replace your DPFE sensor with a new Motorcraft unit.

 

I think I got somthing mixed up here, I changed the egr valve and the little black plastic box with the two rubber lines running into it that is mounted to the side of the throttle body assembly. Is that the map sensor or the DPFE? And yes I reset the codes but it keeps coming back again saying the same thing.

 

The DPFE (Differential Pressure Feedback EGR) sensor is mounted in front of the EGR valve and has the 2 hoses that connect to it (measures differential pressure). I don't know the 4.6L engines as well, but I thought they had a DPFE and not a map sensor... did you replace it with a Motorcraft? projectSHO89 stated to replace with a Motorcraft because after market brands tend to be very unreliable. You can test the DPFE sensor with a mulitmeter to be sure. Here is a link to a great website/resource on the whole EGR system: http://www.fordscorpio.co.uk/egr.htm

 

yeah that was the DPFE sensor that I replaced, so what/where would the map sensor be at?

 

I'm not certain, but I think a MAP (manifold absolute pressure) sensor and a MAF (mass air flow) sensor are essentially the same device and/or serve the same purpose. I didn't think your engine had a MAP sensor; just a MAF sensor. Maybe one of the more experienced and knowledgeable gear heads will confirm.

According to your first post, you already replaced the OEM MAF but never hurts to clean it.