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
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,
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.
Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price
you pay..DEAL with it!
If the passages were cleaned ~1 year ago, I doubt this would be an issue. The
32 ...below closed limit... would usually indicate an open pfe\dpfe sensor.
with the code 33 ....valve not opening.... would seem to verify that the
wasn't able to indicate to the PCM that the EGR was opening. IIRC by 93, you
have a DPFE sensor. This "could" cause the EGR to open too much, too early and
misfire, but i've never seen it happen.
Your miss is very likely unrelated to the EGR concern. How old are the plug
On the 4.6 they tend to burn through the boots and arc to the cylinder heads. If
are original or haven't been replaced in the rememberable past, they are your
culprit. Rule of thumb on 4.6 plug wires is about 5 years.
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!
Thanks for your input also, now I need to determine whether the 93 has
the PFE or DPFE, i think its' the PFE.
I still think you may have plug wire concerns. Pull the wires off of the plugs
check for oil or coolant on the boots. You may find oil seeping into one of the
This contaminates the rubber and causes arcing. Also, if you didn't put
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
of the plug.
Plug wires on these engines can be really troublesone, especilly at high
contamination in the wells will cause arcing, and the grease is an absoulte
wire sets(~$100 or more) can be very expensive so it's hard not to price shop
replacements. Low quality wires(~$30-40) exacerbate the problem. I'm not saying
used cheap wires, I've just seen it happen many times and have been tempted
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
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:
I couldn't find a good picture of a DPFE, but here is a pretty accurate
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
it's on a bracket with the EGR solenoid.
Tom Adkins wrote:
Aaaha, I found a pic of the DPFE at Lincolnsonline. 8th post down, 3rd
fourth pic shows what your hand will probably look like after replacing it. ;)
You might want to bookmark that website. A lot of info about your CV is
to the Town Car. There's a really good bunch of folks at LOL. Very little of the
flaming and bickering often found in other forums.
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??
P.S. I did bookmark those sites!
Good job. A lot of folks don't think to clean the plug wells before pulling
plugs. It sounds like you covered the bases on the wires. It wouldn't hurt to
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
test. This will narrow it down to the offending cylinder. If you feel it under
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
haven't seen everything.
A quick and dirty test of the EGR system is to ground a test light and probe
connector with the engine idling. One side will show battery voltage. The other
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
system is at least able to operate when commanded by the PCM. This will rule the
valve and EVR out as causes for your "no EGR flow" concern. It will also rule
plugging of the EGR passages. This leaves the DPFE, which I suspect is the
If you get no rough idle when "grounding" the EVR then you will need to check
EVR, EGR and passages separately.
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