Steve, KOER Code 31 may mean your EVP is reporting that your ERG did not close all the way.
If you have a replacement EVP the rod length could be incorrect.
EGR could be holding vacuum keeping it open a small bit.
EGR Solenoid/valve could be sticking in the open position.
Your new EGR could be defective (last choice).

 

LOL, that's as crazy as his rainyday issues.... Who in the hell, swapped those wires?
We will have to tackle that rainyday issue after he recieves his 4th computer........

He did fix his lift pump issue..... and Code Reading....

 

I adjusted curb idle speed. That code disappeared.

What remains is code 34 and 41.

With regard to 34, I thought I should test the voltage. There are 3 pins. One pin registers voltage of 5.0. The other pins register nothing. It appears one pin goes back to the ECM and one pin is ground? So I'm assuming voltage is ok?

If voltage is OK, then it's either sticky or not working. With engine running, if I disconnect the electrical connector there is no change whatsoever in engine performance. Also, I cannot feel any vacuum whatsoever if I put my finger on the inlet for the vacuum hose. Is this normal?

I'd like to remove it all together, but there's that PA inspection issue.

I found this procedure:

Testing Procedure:

1. Disconnect the EVP sensor connector. With the ignition ON and the engine OFF, measure the voltage between VREF and SIGRTN terminals of the EVP sensor harness connector. If the voltage is 4vdc-6vdc, the power circuits to the sensor are OK...goto 2.....NOK?...check VREF to battery ground....OK?...SIGRTN wire needs to checked for open condition....NOK?...goto 3.

2. Reconnect the EVP sensor. With the ignition ON and the engine OFF, measure the voltage between EVP sensor terminals EVP and SIG RTN. If the voltage reading is between .25vdc - .67vdc the sensor is okay....goto 4......NOK?...replace EVP sensor.

3. Check VREF voltage at alternate sensor (TPS or BP), sensor disconnected, Ign On, voltage should be between 4vdc-6vdc....OK?...trace EVP VREF wire for open condition in harness....NOK?...rerun KOEO and confirm failure code presence of sensor used for this test.

4. Ign Off, ECM and EVP sensor disconnected, check continuity of the EVP signal wire pin from the sensor connector to pin 27 at the ECM connector, resistance reading should be less/equal to 5 ohms....NOK?...trace EVP signal wire for an open condition and repair.....OK?.....bad ECM.

I'm not sure how to do procedure 2 - which voltmeter probe to which connector?

 

I also took off the EGR valve. It's not sticky and the rod from the bottom of the valve pushes up easily without resistance except the spring.

Voltage seems to be ok. I get a reading of 5.0 between the VREF and sigrtn and a reading of .4 between sigrtn and EVP.

How do I know if the sensor rod is not the right length?

 

Look at post #339 in this Thread. It is called EGO.

 

Yes. I found that. I see two connections to the ECM, one at pin 29 and one at pin 49. That confuse me because the O2 sensor has one wire coming from it that plugs into a white connector, and that has one wire running directly to the ECM. What am I to understand by looking at this? Am I to check the continuity? To pin 49?

 

That would not hurt. You could ground pin 29 using the paperclip method, then check the wire at the O2 to ground. Pos meter lead on O2 wire, neg meter lead on the "Y" pipe.

 

Note the diagram I used was for a 1986. A Truck 1985 may be different on the O2 sensor.

 

Do you think the EVP is old or new?
Do you have a Code 34 or 31 ?

The EGR does not open at Idle, only during normal acceleration.
You should be able to feel vacuum during acceleration.
Do you have a vacuum gage?

After you clear the 30’s codes, you can make a gasket, and block the hole between the EGR and Intake.

 

I was planning to take off the O2 sensor and clean off the soot. Could I just connect the positive wire to the base of the O2 sensor and the negative to the pipe? Is that with battery disconnected?

 

Well that would check the ground between the base and the pipe, but not check the wire to the ECA.

Anytime you remove the ECA connector, it is a good idea to disconnect one side of the Battery, for continuity checks, I would remove the Pos batt terminal.

I would not spray any chemicals on the O2 sensor.

 

OK the only EEC diagram (EVTM) I have for 1985 is for the E-series with the 4.9L and the truck 5.0L may very well be the same. It looks like all 5.0L & 5.8L engines in vans had carburetors in 1985.
The van 1985 EVTM 4.9L shows the EGO sensor goes between pin #29 and the other end has the ground symbol on it.

 

What are the colors of the 3 wires going to your the EVP sensor?

 

5.0 vdc is good.

 

They appear to be light brown, and two black.