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Discussion Starter · #1 ·
Got a 93' LX 1.9L with an interesting idle problem, and I also just failed emissions for high NOx, really high actually like 3-4 times the limit. I think the idle problem may be related to the high NOx and was curious to see if anyone here has had simliar issues. This forum has always been a huge help.

With the idle, when I come to a stop after driving it will hold steady at 900rpm for 10-15 seconds and then will start to lope and droop pretty hard. It will go rapidly from like 400-700 rpm and I end up having to keep my foot on the throttle while out of gear to manually hold the idle up or it seems like it will stall- it has stalled a few times where I don't use the throttle to hold it.

Some older posts suggested that the EGR might be the problem and to test by unplugging the DPFE sensor. I found that unplugging it made the idle stay smooth for longer when stopped, but eventually the loping would come back- but it wouldn't drop as far as when the DPFE is plugged in and it had a kind of steadier 600-800 rpm lope.

I found one post from 2016 mentioning the same problem and said the reason the loping only happens after a delay while stopped is because if the EGR valve is stuck, the idle lope won't show up until the exhaust gas is diluted from not moving for a while.

I'm gonna do all the normal checks like for vacuum leaks, clean out the EGR tube and check it for operation, check the O2 sensor, and whether the Cat is hotter on the outlet than the inlet, but has anyone else had EGR problems that lead to the same symptoms, and success fixing it? If the EGR really is the most likely problem I can focus there first and hopefully save some time.
 

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Be sure to try a replacement Idle Air Control Valve, and check for a leaking brake booster - it has a large rubber diaphram inside it which can be leaking. It is also possible to replace the fuel pressure regulator that is under the intake manifold. My 95LX has an idle so slow that it dies at most traffic stops, like stop signs or traffic lights; though it runs smoothly when being driven.. I still havent found the root cause of mine, and it wont pass the annual safety inspection as it is. So it now sits while I use my other 2nd gen Escorts.
 

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Discussion Starter · #3 ·
Ah interesting I wouldn't have thought of the brake booster, thanks I will check that out as well. Hopefully it's not anything fuel delivery related as I've found it's a huge pain to disconnect the lines. I'm going to be working on it this weekend and will post back with results.
 

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Another common vacuum leak is caused by a perished rubber elbow on the PCV plumbing where it connects to the intake manifold.

It does seem like high NOx would seem likely to be caused by vacuum leak, which would lean out the mixture, especially at idle where the air flow is at a minimum.
 

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Discussion Starter · #5 ·
Did some diagnosis this morning and it looks like there are multiple things going on at once.

I do have a vacuum leak where the EGR meets the intake manifold. Sprayed carb cleaner in there and the revs jumped. I was hoping this wasn't the case but I'm not surprised because the top EGR bolt felt like it was crossthreaded last time put it in but it was too late by the time I realized it and so I just tightened it as best I could and hoped for the best. I'm guessing I'm going to have to take the intake manifold out and heil coil the threads before reinstalling.

I also checked the EGR function itself with a vacuum pump. The valve itself seems to be working as if I apply vaccum at idle the engine dies, and when i apply vacuum with the car off I can hear the valve opening/closing.

But the EGR vacuum solenoid is doing nothing- I held the throttle open at like 2000 rpm and got zero vacuum coming from the EVR solenoid, it's not sending anything to the actual EGR valve. I will check the rest of the forums but if anyone can link to a post on how to test whether it's the EVR solenoid that's broken or if it's the DPFE that's not sending the right signal I'd greatly appreciate it! I would bet that it's the EVR because I know the DPFE at least functions because when I unplugged it the check engine light came on.
 

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The DPFE is exposed to all the soot and crap from the exhaust.

In my experience 8/10 times it's a dirty DPFE. I would just replace it personally. Wouldn't be surprised if it immediately threw an "p0401 insufficient EGR" code afterwards, or just immediately runs better.

All ford's 90's-2000's with a DPFE like this; I just replace it. Taurus, ranger, explorer, mustang... Whatever.
 

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Discussion Starter · #7 ·
Thanks- I did take a look at the EVR to try and test it and found a couple interesting things. One is that when I tested the voltage going to the EVR with the key in the on position, it was only 10.6 volts. That seems too low- battery voltage is 12.6 so there may be some corrosion in the harness or something, which seems really intimidating to try and dig into.

I took the EVR out and did a few tests. There is resistance of about 50 ohms between the pins and although I broke part of the plastic on the cover taking it off, when battery power was applied to the EVR pins the metal post in the center gets magnetized, so electrically it seems good. But mechanically I think it's stuck because if I blow air through the EVR ports, a tiny bit bleeds through but there is no change regardless of whether it's energized or not- the air flow is exactly the same.

Since the EVR and the DFPE are both fairly cheap I'm going to replace them both. But does 10.6 volts sound like it would be enough to work? I would think it should really be battery voltage.
 

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Thanks- I did take a look at the EVR to try and test it and found a couple interesting things. One is that when I tested the voltage going to the EVR with the key in the on position, it was only 10.6 volts. That seems too low- battery voltage is 12.6 so there may be some corrosion in the harness or something, which seems really intimidating to try and dig into.

I took the EVR out and did a few tests. There is resistance of about 50 ohms between the pins and although I broke part of the plastic on the cover taking it off, when battery power was applied to the EVR pins the metal post in the center gets magnetized, so electrically it seems good. But mechanically I think it's stuck because if I blow air through the EVR ports, a tiny bit bleeds through but there is no change regardless of whether it's energized or not- the air flow is exactly the same.

Since the EVR and the DFPE are both fairly cheap I'm going to replace them both. But does 10.6 volts sound like it would be enough to work? I would think it should really be battery voltage.
Man it's been a while, but I feel like it should be ~5v
 

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Discussion Starter · #9 ·
Thanks; hmm well if it doesn't have to be battery voltage then maybe it'll be ok. One of the wires was loose in the connector but hopefully I can just push it back on the pin when I install the new EVR. Just got the new one and new DPFE delivered. Should have it installed by tomorrow.
 

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Discussion Starter · #10 ·
I installed a new DPFE and EVR. In an attempt to take the easy route to pass smog, I tried sealing up the edges of the EGR with permatex copper rather than taking it all apart and getting a new gasket to try and seal the vacuum leak.

Unfortunately, the only thing that is different now is that the check engine light is on, throwing code 327 "PFE circuit below minimum voltage" according to my haynes book. When I test for vacuum coming from the EVR with the throttle open, I get nothing. The vacuum is at 0 although the needle does twitch a little. The EGR system is still not working at all.

So I know I need to take the EGR off and seal it to the intake manifold correctly, and I still am getting a loping idle too, so really nothing is improved. I guess since the check engine light is on now, a sensor that was dead before is now working again. Does anyone know what code 327 typically indicates? Could my EGR pipe be clogged so bad the DPFE can't take a measurement and that's why it's below voltage? Or does the code mean it's a electrical issue and it's not getting enough voltage due to a wiring problem? Thanks for any help- searching online about code 327 is not too encouraging, it seems like it could be a lot of different things. I would hate to have to get rid of the escort, it otherwise runs pretty good and has been a great reliable car.
 

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Discussion Starter · #12 ·
Thanks, yeah when i check for vacuum going to the EGR I'm getting nothing so it's not getting signal to open.

I reseated the EGR valve itself on the intake and the loping idle went away, at least so far which is good. But it's still throwing code 327 so I gotta think it's a wiring or PCM issue. The EGR valve itself works fine mechanically and didn't have carbon blocking it or the pipe. It looks like the problem is electrical.
 

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Discussion Starter · #13 ·
And now that I'm thinking about it, the check engine light comes on immediately after startup with a cold engine, when the EGR should be closed. So anyone smarter than me please correct me if I'm wrong, but the problem probably isn't that the DPFE isn't getting a correct reading of exhaust flow because of a bad hose or something and that's what's throwing the code, it's that it's not getting the power it expects to see at all.
 

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Discussion Starter · #14 ·
I'm pretty confused. To test things, I took out the new DPFE out and put the old one back in, and the check engine light went off.

The EGR has no vacuum being sent to it at any RPM with both the new or old DPFE, but somehow the old version doesn't trip the 327 code. The one difference between the two I could measure is that the old one has slightly more resistance between the pins- about 46 k ohms vs. 3 m ohms in the new.
 
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