For 93GreenF150:

It seems like the CEL should at least come on some of the time when it is running. It may be that the EVP voltage is acceptable to the computer when the valve is supposed to be open, hence no CEL then. During KOEO, the computer is complaining that the voltage is too high at the sensor for what should be a closed valve. But then there is no hard and fast rule about when the computer will light the CEL. It does try to "manage" any problems it sees, and may not think the issue bad enough to "worry" the driver.

Code 21 means the engine isn't warmed up during KOER, or the ECT is bad.
Code 42 is oxygen sensor indicates always rich.

For Austinbronco:

If there is no functioning air pump, there is no point to the TAB and TAD vacuum lines. Leave the solenoids electrically connected so the computer thinks they are still there, or it will set codes. You can either plug the vacuum lines coming off the TAD/TAB, plug the vacuum line coming off the coffee can, or plug the vacuum line going into the coffee can.

I agree with your conclusion, for what you have a straight vacuum line from plenum to EVR and then from EVR to EGR valve should be all you need.

The obscured object in the diagram is the MAP sensor. I need to modify the diagram with photoshop so that the FTE logo doesn't step on it.

 

for austinbronco... our trucks are routed very similar, if not exactly the same... and it looks factory. not rigged.. but WHO KNOWS?? Fefarms, I have one more silly question about the EVR... Why would anyone build a solenoid that has a spring pushing it in one direction and an electrical coil to do the same... kinda like having two hot valves in the shower and no cold?

 

Regards to your code 41.. I had a code 41 KOER after having Trannsmission Inststalled. This relates to your O2 sensor . Went under the truck yesterday and noticed the wire harness was smashed. Pulled out the O2 sensor and sure enough there was a broken white heater wire. Patched it up and put it back in and running fantastic. apperently the Trans shop shovede the tranny and transfer case into it and did not notice it. Also have been having code 31 for a couple of years . Cant figure this one out.
Davud C

 

Routing the vacuum lines the way fefarms suggested has seemed to have gotten rid of the code 32. Hasn't thrown that code in a few weeks now. It was still throwing 41, though, so I replaced the O2 sensor. For a few days, it threw 41 even more frequently than before, i.e. every time I drove. It has since mellowed out a bit and gone back to throwing the code about once a day (I drive a lot.)

According to this page, http://www.dalidesign.com/hbook/2digit.html , 41 in the memory means the system ran lean for at least 15 seconds. I can't imagine my system is running lean. The exhaust smells very rich and my gas mileage is horrible (8 mpg in the city.)

 

Did you test the voltage going to the 02 sensor? It is the black wire. YOu have either 3 or 4 wire harness mine has 4 2 white wires ( called heater wires) 1 black ( hot) and 1 grey (ground) according to my cousin ( ford tune-up mechanic ) voltage should be < 1.0 volt . Optimal is .35-.55-volts.I put a needle through the black wire to get contact then tested with volt meter. I was getting real low reading which tells computer it is lean therefore computer gives it more gas which is why poor milage. After 02 sensor did you disconect battery for atleast 5 minutes? This will let the computer relearn.
David C
1990 f250 7.5 4wd and f150 5.0 2wd

 

Have very similar problem to above. EGR tests 5.0. Perfect. However, EVG has no voltage at all. FOrd f150 5.0. code 34 EGR problem. Idles rough.