EGR workaround for 3.0 with composite manifold for emission testing

[Rangstang]

I needed to get the 99 Ranger with 3.0L and 2003 composite intake through emissions here in Arizona recently. Here they merely connect to the diagnostic port and check for codes in the PCM. They don't even pop the hood for OBD II vehicles (after '95). I bought the truck already modified and obviously without an EGR valve, I had a check engine light.

After trying a few ideas to fool the PCM, I thought about the way the system works with regard to the DPFE sensor looking at negative pressures and recalled a graph I found online that showed how to test the DPFE by putting vacuum on the REF port of the sensor and checking the voltage. When the vacuum increased, the voltage linearly increased. This got me thinking that I might be able to connect vacuum to the REF port through the EGR solenoid so that the voltage would automatically increase whenever the EGR solenoid receives electrical signal. Viola! it worked. I merely had to add a vacuum tee and 6" section of vacuum hose to the vacuum reservoir, then connect a hose from the tee up to the EGR solenoid and the other port of the EGR solenoid directly to the REF port on the DPFE sensor. Diagram below:

 

[Rangstang]

Driven the truck another 100 miles and still no codes.

 

[adsm08]

That's awesome. I never even thought of that.