code 32/33 on 93 C/Vic

Hey folks, Having performance problems on my 93 C/V w/120K mi. Feels like a 'miss', Maybe.. Checked MAF, clean as a whistle. Replaced plugs, no help. With engine at oper. temp., ran KOEO(twice) and got code 32 first
time, code 33 second time. Code 32: EGR Valve Position(EVP) sensor or Pressure Feedback EGR (PFE) sensor - signal voltage is below closed limit or has gone beyond set limits. OR, Problems with EGR valve controlling. Code 33: EGR Valve Position(EVP) sensor or Pressure Feedback EGR(PFE) sensor indicates EGR valve is not opening. OR, EGR Valve Position(EVP) sensor or Pressure Feedback EGR(PFE) sensor indicatres EGR valve not sealed(closed) properly. Last year, a Ford mechanic friend helped me clean out the carboned up EGR passage way, and EGR system was working properly. Have any of you had this similar problem ? Is it likely the EGR or the Sensor(s)? I hate to just go shot-gunning by replacing parts. Thanks for your help, John
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searching this group on google groups will point out the the more common culprit seems to be the PFE or DPFE sensors.
Your symptoms bear that out, as the exhaust side pressure port clogged would make it seem as tho there weere low exhaust pressure.
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Backyard Mechanic wrote:

If the passages were cleaned ~1 year ago, I doubt this would be an issue. The code 32 ...below closed limit... would usually indicate an open pfe\dpfe sensor. Coupled with the code 33 ....valve not opening.... would seem to verify that the PFE\DPFE wasn't able to indicate to the PCM that the EGR was opening. IIRC by 93, you would have a DPFE sensor. This "could" cause the EGR to open too much, too early and cause a misfire, but i've never seen it happen. Your miss is very likely unrelated to the EGR concern. How old are the plug wires? On the 4.6 they tend to burn through the boots and arc to the cylinder heads. If they are original or haven't been replaced in the rememberable past, they are your likely culprit. Rule of thumb on 4.6 plug wires is about 5 years.
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Tom Adkins wrote:

Tom, I failed to mention that I did have a miss 2yrs. ago , replaced plugs and wires and that solved the miss problem, the wires at that time were the original Ford wires, but miss actually was a plug, ugh!!, shoulda replaced plugs first!
Backyard, Thanks for your input also, now I need to determine whether the 93 has the PFE or DPFE, i think its' the PFE. Thanks, John
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JRnNC wrote:

I still think you may have plug wire concerns. Pull the wires off of the plugs and check for oil or coolant on the boots. You may find oil seeping into one of the wells. This contaminates the rubber and causes arcing. Also, if you didn't put dielectric grease on in the boots when you changed the wires, you still may have one with a carbon track burned on the inside. It will arc between the plug and boot to the base of the plug. Plug wires on these engines can be really troublesone, especilly at high miles. Any contamination in the wells will cause arcing, and the grease is an absoulte must. Good wire sets(~$100 or more) can be very expensive so it's hard not to price shop for replacements. Low quality wires(~$30-40) exacerbate the problem. I'm not saying you used cheap wires, I've just seen it happen many times and have been tempted myself. My personal observation has been that OEM Motorcraft wires last longest when installed properly. Even good wires like NAPA gold series tend to fail earlier than they would be expected to. YMMV
Your 4.6 probably uses a DPFE sensor. Here's a pic of a PFE sensor. They are either black or grey: http://www.niehoff.com/techtips/n_sen.html I couldn't find a good picture of a DPFE, but here is a pretty accurate drawing. The sensor is silver in color: http://www.fordscorpio.co.uk/egrsensors.htm The DPFE is mounted to the back of the intake manifold in a pretty tight place. IIRC it's on a bracket with the EGR solenoid.
            Good luck.
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Tom Adkins wrote:
Aaaha, I found a pic of the DPFE at Lincolnsonline. 8th post down, 3rd picture. The fourth pic shows what your hand will probably look like after replacing it. ;) http://www.lincolnsonline.com/forum/showthread.php?t3277&highlight=DPFE
You might want to bookmark that website. A lot of info about your CV is applicable to the Town Car. There's a really good bunch of folks at LOL. Very little of the usual flaming and bickering often found in other forums.
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Tom, Thanks again for legwork finding this info, it will be very helpful. IIRC, I paid somewhere around 60bucks for the wires when I replaced them 2yrs. ago from Advance auto. I will check plug holes for trash, etc. I had devised a method the first time I changed plugs to clean out plug holes pretty good. Took a piece of 3/4" copper tubing(not too long), held one end into vacuum hose and after removing boot, inserted the other end into spark plug well. The 3/4" tubing fit just nicely over the plug. Then visually inspected well before removing the plug. And I did definitely use silicon grease on the boots. I'll have to re-check all that. I hope it is not a plug wire, hmm, now where'd I put that receipt?? Thanks, John P.S. I did bookmark those sites!
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JRnNC wrote:

Good job. A lot of folks don't think to clean the plug wells before pulling the plugs. It sounds like you covered the bases on the wires. It wouldn't hurt to look closely at the boots, though, just to rule out the possibility. I forgot to ask, when do you feel the "miss"? My bad, as that is the obvious question. If you feel it at idle, you can do a cylinder balance test via the EEC self test. This will narrow it down to the offending cylinder. If you feel it under light load, it is possible that it's related to the EGR concern. Like I said, it could happen,I've just never seen it personally given the fault codes you have. I certainly haven't seen everything.
A quick and dirty test of the EGR system is to ground a test light and probe the EVR connector with the engine idling. One side will show battery voltage. The other is the control or "ground" side. When you probe that terminal with the light, it will activate the EVR and open the EGR valve causing a rough idle and possible stalling.(The test light should glow dimmer than normal). This verifies that the EGR system is at least able to operate when commanded by the PCM. This will rule the EGR valve and EVR out as causes for your "no EGR flow" concern. It will also rule out plugging of the EGR passages. This leaves the DPFE, which I suspect is the culprit. If you get no rough idle when "grounding" the EVR then you will need to check the EVR, EGR and passages separately.
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