The Actron code reader said I have a 334 KOEO. Looks like a problem with the EGR...

334:
EGR Valve Position (EVP)
sensor – signal voltage
higher than expected
(closed valve position).

I got a 334 for the CM too.

The truck idle is smooth when warming up, but rough at idle when warm. It's been this way since I got it 4 years ago. I passed smog 2 times but the last time just barely. I need to pass again now.

What should I change, or should I take it off and clean any deposits. From searching it could be either the sensor or the actual plunger thing on top of the EGR.

Thanks for the help.

 

 

I cleaned the egr and cleared the code. The egr wasn't very dirty and the egr pressure feedback plunger moved freely. The truck ran great for a bit, shifted really nicely, but the code is back.

With a warm engine, I tested the voltage at the vacuum solenoid and I get 12+. I think I read that it's supposed to drop as the engine warms up, but I can't find the link someone posted.

What do I do next?

Thx.

 

My 96 FSB with 5.8 has a DPFE sensor (black about the size of a deck of

cards) located forward of the EGR.

I can't see one in your photo, anyway, can you locate yours?

 

I'm not sure about the voltage, but if you can, cap the line running to the EVP with a golf T. Or if you have a vacuum gauge, attach it to the line running to the EVP. If you are pulling vacuum above 1"-Hg, there is a problem with the EVR. There should be at least 10.5 volts on VPWR terminal with ignition switch in RUN position.

It could be the EVR is allowing vacuum through, therefore allowing vacuum to pull the pintle up on the EVP, pulling the plunger up on the EGR, allowing exhaust gases back into the intake.

Also note there are 2 different EVR's. One gray and the other black. Only replace with same color if diagnosing points to malfunctioning EVR.

 

The item in the photo is the EGR Valve Position (EVP) sensor. There is no pressure measured on the older style EGR position feedback. More than likely you have a faulty EVP, an open wire/connector, no vacuum to the EVR or a faulty EVR.

As noted before the VPWR supply to the EVR is always there with the key in the On/Run position. The PCM (computer) turns the EVR on/off by supplying a ground to the return side of the EVR. This on/off process modulates the EVR which in turn controls the amount of effective vacuum supplied to the EGR valve.

For reference:

Fuel Injection Technical Library » EGR Valve Position sensor (EVP)

Fuel Injection Technical Library » EGR Vacuum Regulator (EVR)

 

The OP has an 1995 model which uses the older style EGR position feedback. Yours uses the newer, and still used, DPFE (pressure) EGR feedback setup.

 

That's the page I was looking for...

I removed the green line and applied vacuum to the EGR and it held vacuum. I could see it move. The idle got rough and it wanted to stall.

I connected that back up and put the vacuum on the green line at the EVR and the gauge showed no vacuum.

From the library page above:
With everything connected and the engine running ground out the pin 33 side. The EGR vavle should open and the engine RPM should change.
Ford EGR valves will open 50% at 4 inHg of vacuum, and 100% at 8 inHg of vacuum.


Auto electrical is not my strong point. How do I do this?

 

Use a jumper wire attached to the Brown/Pink wire (This goes to pin 33 of the PCM) then momentarily touch the other end of the jumper to a good ground. This will activate the EVR to full ON. Do not leave the jumper on for more than a few seconds.

Use this for reference:

courtesy of oldfuelinjection.com

 

I hooked up a wire to Pin 33 and ground to the negative terminal of the battery. The EGR opened. I could see it and the truck began to stumble.

The EVR makes noises when I turn off the truck. Is that normal?

 

Some make more noise than others, but yes it is normal.

 

I'm still not sure which is causing my problem. If the EVR is working properly, it seems like the problem is the EVP.

How do I test this part? Nothing is mentioned on that fuel injection page.

 

Check resistance if the evp. I don't think it should be above 5k ohms when the pintle is resting and no more than 100 ohms when completely pushed up. I don't have my book, but will check this morning after work. I may have it opposite in regards to its position in ohms.

 

After reading the article, it says that, "At idle, the EVP sensor signal should be apprx. 5000 ohms(EGR valve closed), reducing to 100 ohms when the EGR valve is fully open."

Hope that clears my prior statement up.

 

You are much better off measuring the output voltage of the EVP. The values are listed on the page I linked to before.