Need some help with my troubleshooting of a code 327. I have a '93 F250 4X4, 351W. Without fail, the CEL light comes on as soon as the truck warms up, and remains on constantly. The only code I get is 327, "EVP or DPFE circuit below minimum voltage".

I have followed various troubleshooting suggestions from both here and my Haynes manual. I also removed and cleaned the EGR tube (was pretty clean to begin with). I am fairly certain the EGR valve and EVP sensor are OK. I'm now starting to point my finger at the EVR.

My understanding from another site is that the EVR should hold vacuum when applied to the shorter of the two ports with all electrical connections disconnected. It does not. It doesn't leak to the top port, but rather seems to be leaking somewhere internally. Is this a sure sign of a bad EVR?

 

The EVR does not hold vacuum with no power to it. It is designed to suck air all the time and modulate vacuum to the EGR valve as commanded by the computer. That's why it has a filter in the dome on top of it. So, that is not a sign of a bad EVR.

 

First off, thanks for the response.

I realize I came here asking for help, which obviously means I am less knowledgeable than others, but I'm a bit confused by your response. My Haynes manual says to do the following:

------
Conditions for test: KOEO, EVR electrical connector disconnected.

Remove the vacuum supply line from the EVR solenoid. Install a vacuum gauge to the EVR outlet port and using a handheld vacuum pump, apply vacuum to the manifold vacuum supply inlet port. Vacuum should hold and no vacuum should be indicated at gauge.
------

The only vacuum gauge I have is built into my hand pump. I *think* that when I run this test, I should see vacuum indicated on THIS gauge, which is how I would know that vacuum is holding. I do not; i.e. the meter never shows any vacuum.

Since I don't have a gauge to put on the outlet port, I put my finger over it. I do not feel any vacuum. So, it appears to me that the EVR is not sending vacuum to the outlet port during this test (correct), but it also is not holding vacuum on the inlet side (incorrect). Thus, I believe my EVR is faulty.

Is there something I am not understanding?

Thanks in advance to anyone that can help out here.

 

Maybe this will help: https://www.ford-trucks.com/forums/s...highlight=EVR+

 

Thanks for that link, good thread. I have never fixed my code 32 on my 1991 460 and look for info on EGR problems. Soon we will take another trip and I want the code 32 fixed before we go. I only get the CEL when the truck is heavily loaded and pulling hills, so I suspect a vacuum leak, but haven't found it. If you know of other good threads on this subject I would like to see them, thanks.

 

eds72, I ran across this a while back. I beleive the Haynes manual is wrong on testing that evr, because I bought a new one and it did not hold vacuum either. What I did was put my code reader on the truck and activated all the sensors and the old evr didn't click. So I did use the new one because it did. Just held on to it when I started the test and the new one clicked.

 

KOER attemps to cycle all of the actuators, EVR is an actuator. If you hook up your vacuum pump to the EGR side of the EVR and run KOER you should read vacuum, and feel it click, when the EVR cycles. You can use your vacuum pump as a vacuum guage. I am assuming your vacuum pump is like a mityvac. You should read less than 1 inch vacuum before the EVR cycles.

Good luck and please let us know what you find.

 

Thanks for all the advice. Here's where things now stand.

First, I pulled my codes again, both KOEO and KOER and this time got 327 and 328, both EGR related codes.

With the EVR removed from the vehicle, I energized it by connecting it directly to the battery with jumers. I did not hear it click or make any sound that indicated it was getting voltage. However, when I plugged the EGR side, and applied vacuum to the supply side, it DID in fact hold vacuum (sort of). I applied 20in of vacuum and watched it slowly decrease. It seemed to be losing about .75in/second.

Next, I put the EVR back into the truck, but with my vacuum gauge connected to the EGR side. I drove around for several miles and monitored the gauge. At idle, or WOT, I saw no appreciable vacuum. At part throttle, I would get a steady 5in of vacuum - never any more. As soon is I mashed the pedal or returned to idle, the vacuum would immediately drop to nothing.

This seems like proper behavior, except that 5in of vacuum seems like it might be low. I did check the vacuum supply to the EVR and it's around 16-17 in. So, I guess these are my concerns:

1. Is 5in of vacuum sufficient to operate the EGR system?
2. Should I hear some sort of "click" when I manually energize the EVR?
3. Is 16in enough supply vacuum to the EVR?

 

During KOEO or KOER test, I never heard a click from the EVR.

 

After posting last night, it occured to me that I could run a test myself to answer my question about ~5in of vacuum being enough to properly activate the EGR. With my ohm meter connected to the EVP, I slowly applied vacuum to the EGR. Sure enough, The resistance slowly dropped as I applied vacuum right up to about 6in. At that point, the resistance remained constant (200 ohms I believe) no matter how much vacuum I applied. Thus, it would appear there is no problem with my EVR.

I came across this thread where someone with EGR problems eventually traces it back to a component of the A/C vacuum system. So, when visually inspecting vacuum lines, I found one that is suspicious. It is about 4" long and connects to a tee near where the source line comes from the manifold. The opposite end connects to the large, black plastic box attached to the firewall. The hose pushes straight down on to this box very near the dipstick for the tranny.

Anyway, this hose appears to have a pin sized hole poked in it right by where it connects to the large black plastic box. I removed the hose and applied vacuum to each end. When I applied vacuum to the end nearest the hole, it leaked right out (this is the end connected to the plastic box). When I applied vacuum to the side attached to manifold vacuum, it held vacuum as if it was plugged!

I do have occasional problems with the A/C blowing out the defroster, but it usually flips back over fairly quickly. It never occured to me that these problems may be related?

Should this line have a hole in it? Should it be plugged from the manifold side? I can't imagine it should be anything but a regular vacuum connection, but if anyone knows otherwise, please enlighten me.

 

Youe EVR is functional, the 327 and 328 refer to the EVP voltage which should be about 0.50 volts to the PCM at EGR closed. You probably need either an EVP sensor or an EGR valve or both.

 

Let me present another possibility. I think you may have found your problem or part of your problem. If your system is activating the EVR and attempting to move the EGR but vacuum is insufficient to move it, due to leaks, the EVP would get an unexpected reading and throw a code.

I suspect a similar problem with mine because I usually throw a code while climbing a long hill with a loaded truck, so my throttle is somewhat open, vacuum is probably low and with vacuum leaks my EGR doesn't work right.

BTW the EVP clicking is something I repeated out of another post, I don't know that it must click to work, some of them may be quiet.

If there is supposed to be a leak there it should show on the vacuum chart.

Did you read where some replacement EVPs do not work with some EGRs?

Thanks for that link.

 

Well, I think I may have had a breakthrough.

I took a step back and followed the Haynes procedure from the beginning. I had tested the EVP previously, and all appeared OK. When performing the continuity test, I looked VERY carefully at my meter (I have a really lousy old Radio Shack cheap analog multimeter). I noticed that it read somewhere around 300 ohms when I manually depressed the pin all the way. The Haynes said it should read 100 ohms or slightly over. Since I really don't trust that meter, I took the EVP with me to AutoZone when I went to get a piece of vacuum hose. They allowed me to borrow their digital multimeter, and sure enough, resistance never went below 300 ohms on my old EVP. After careful visual verification of pin length on the EVP they stocked, I put the multimeter on it. It read 5000 ohms with the pin extended, and 120 with it depressed.

I went ahead and purchased it and installed it in the truck upon returning home. I took the truck out for a drive, and was very disappointed to get a CEL within a very short time. In fact, it came on even sooner than it does normally. I returned home and pulled the codes. The first thing I noticed was that I didn't appear to get any codes from the KOEO test. I would always get 327 or 328 (or both) before. From the stored codes, I got the usual 327, 328, but also a 332, which is "Insufficient EGR flow detected". So, I cleared the codes and took it for another drive. Almost immediately, I got a CEL. Returned home to pull the codes, and got only 332 from the stored codes.

So, my theory is that I have fixed the problem with the sensor, but now have some blockage in the EGR. I'm guessing it wasn't being reported because if the EVP was saying the EGR wasn't opening all the way, it wouldn't expect much in the way of EGR flow. Now that it's reporting full opening, it realizes it's not getting sufficient flow.

One of the first steps I took to deal with this problem was to remove the EGR and inspect it. It looked pretty good to me, but I was unaware of the small openings that seem to be the source of people's problems. I just checked the large pipe, which looked pretty clean. So, I'm now off to search the forums to see exactly what these small ports are and what is the best strategy for cleaning them.

I think I see some light at the end of the tunnel. Thanks to everyone that has pitched in with suggestions and information in this thread. I'll be sure to post the final outcome; perhaps it can help someone in the future.

 

Yes, the A/C out the defrost thing is usually a vacuum problem.
Could there be a check valve in the manifold side of that line making it seem plugged?

 

Not sure about a check valve. I don't think so, though - It just looks like a crappy hard plastic line with a hole in it. It's bent 90 degrees, and appears as thought it has gotten hot and perhaps fused together on the inside. There's a hole poked in it just to the non-manifold side of where it appears to be "kinked". I replaced it with a new line last night.

After searching last night, I became disappointed with what I found. It looks like trucks from my year ('93) don't actually have any way to measure EGR flow other than how far it thinks it is open (EVP). Thus, I'm now skeptical that cleaning my EGR will do anything. I'm also confused - why are there different codes for "Insufficient flow" and "valve not at expected position"? How could it possibly differentiate between these 2 conditions?