Here is what you need: A simple 10K Ohms 10 turn variable pot and a digital multimeter
How to do it:
1. Both wires will be dark green, the one we want is connected somewhere on the ecu. With a multimeter at the Ohm setting, find the green wire that reads 0 O Ohms at the ECU connector and EGR sensor. There are not that many Dark Green wires on the ECU connectors.
2. Cut the signal wire far away enough so you can splice both ends. See picture 2.
3. Connect the pot like on the first picture. You might want to extend the wires to the cab so that you can make adjustments while driving.
4. Turn pot all the way to one end and measure pin 1 and 2 on the pot with a multimeter, using the Ohm setting, to make sure it reads 0. If it reads 10 000, then turn the other way.
5. At 0 Ohms, the signal is unaltered and the EGR system running at factory settings. As you increase the resistance, the ECU thinks the vavle is less open than it really is, and will open it more, letting more EGR flow in.
6. While driving...Slowly increase the resistance. You might find that the car starts to be jerky and not as smooth. back off until all signs of erratic engine running is gone. Might be a good Idea to let someone else drive or increase the resistance. Remember: Safety First.
7. You are done. Congrats. Now measure your increased mpg.
The beauty of this is the way the system works, the ECU has no way to find out the signal is being altered (unless you ground directly the signal, then it would trigger a CEL). Another thing is that at normal highway speeds and Wide open throttle, the ECU uses no EGR whatsoever. It's only part throttle that gets EGR flow. That means this mod should give you better city and combined mpg. Enjoy.
Here is how to wire the pot:
Here is the wires you need:
This is what our EGR valve looks like, although this is from another car:
Now I have not tried this yet, but as soon as I can get my hands on a variable 10K Ohm pot, I will. They are kinda hard to find here. eBay should have tons though.