Just Dumped Codes...Advice ?\\?

[shootshescores]

I've owned my 89' for 7 years now. I bought it completely stock with the exception of a removed air silencer and an offroad H-pipe. The previous owner was still utilizing the stock mufflers so soon after buying the car I got a set of 40 series flowmasters. Not very long after the new mufflers, my check engine light started acting up. The light isn't constant, it comes on sporadically while driving, and very rarely at idle. After a poor performance at the dyno (203hp/270tq) I decided I would look into it.

So I dumped the codes using the jumper wire technique.
It dumped a 67 ,because I accidentally left the car in gear, and a 31.
The 31=EGR Valve Position/Pressure Feedback EGR Circuit Below Minimum Voltage

Can anybody give me some pointers on what to do next to fix the problem?

 

[HISSIN50]

Check the KOEO voltage at the EGR position sensor. It should be below ~0.50 volts.

You can also pull the sensor and check dynamic voltage as you depress the plunger.

Then give a quick check to the vac line to the EGR itself. This line being screwed up should generate a code 33 but a weak vacuum signal could create only a 31.

Good luck.

 

[jrichker]

CODE: 31 (KOEO) - EVP circuit below minimum voltage. Vref (5 volt reference voltage supplied by the computer) missing or broken wire or bad connection in circuit. Use a DVM to check for 5 volts on the orange/white wire. If it is missing, look for +5 volts at the orange/white wire on the TPS or MAP sensor located on the firewall near the center of the car. Use the black/white wire for the ground for the DVM.
With the sensor removed from the EGR and still connected, press the plunger and watch the voltage change on the brown/lt green wire. Pull the passenger side kick panel and measure the voltage at the computer. You will need to remove the plastic cover over the wires and probe them from the backside. A safety pin may prove very useful for this task. Use pin 27, EVR input (brown/lt green wire) and pin 46, signal ground (black/white wire) to measure the voltage. The orange/white wire is Vref and should always be 5 volts -/+ .25 volt. Be sure to measure Vref at the EGR sensor to rule out any broken wires or bad connections.
Measuring the voltage at the computer helps you spot broken wiring and intermittent connections.

 

[shootshescores]

I checked the orange/white wire and it was at 5 volts, so that checks out good.
I checked the vac line to the egr and it is in good shape.

I have not removed the EVP sensor to depress the plunger while checking the brown/lt green wire.
What voltage should I look for when doing this?
Will I have to replace any gaskets after removing the EVP?

 

[HISSIN50]

The sensor should baseline under 0.50 volts (if they are above that but below the min threshold, that can lead to drivability issues).

 

[shootshescores]

The sensor should baseline under 0.50 volts (if they are above that but below the min threshold, that can lead to drivability issues).

After removing the sensor off the back of the EGR and checking the EVP sensor on the green/brown wire, it read zero volts during the check. Zero before depressing the plunger and zero after. Also, I removed the EGR from the throttle body and noticed a lot of carbon built up around the post that depresses. I checked out a new one at the auto parts store a few days ago and it depressed easily. Mine did not depress easily like the new one.

What do you guys think:
I still have to purhcase a new throttle body for my CAI & RPM II combo. Should I bother to replace the EVP/EGR or just get a throttle body with EGR blank and remove the entire system?

 

[shootshescores]

Anyone?

 

[jrichker]

Try cleaning the 10 pin salt & pepper shaker connectors.

 

[HISSIN50]

After removing the sensor off the back of the EGR and checking the EVP sensor on the green/brown wire, it read zero volts during the check. Zero before depressing the plunger and zero after. Also, I removed the EGR from the throttle body and noticed a lot of carbon built up around the post that depresses. I checked out a new one at the auto parts store a few days ago and it depressed easily. Mine did not depress easily like the new one.

What do you guys think:
I still have to purhcase a new throttle body for my CAI & RPM II combo. Should I bother to replace the EVP/EGR or just get a throttle body with EGR blank and remove the entire system?

Testing at the sensor itself: if you have 5 volts into the sensor and nothing egressing it, there's an issue (you did leave it plugged in, we assume). If there's input and no output, that sounds like an issue with the sensor itself.

 

[shootshescores]

I definitely left the sensor plugged in during testing. It sounds like a bad sensor to me. Voltage coming in but nothing coming out. Since I need to pick up a new throttle body anyways, now I'm leaning towards deletion of the system. Since it hasn't been operational for years, I really won't be missing anything. I'll just have to get the computer flashed to erase it. Any ideas how much a quick flash runs these days?

My other option is to purchase the kit from ford racing that includes a new EGR valve w/EVP sensor, a coolant temp sensor, and air charge temp sensor all for $45.00.

If the flash is going to be more expensive than the sensors I think I'll just go that route. What do you guys think?

 

[HISSIN50]

Part of FMEM is to have the EGR function shut off if a hard EGR code is logged. I haven't been able to confirm this in real time on an aero fox however.