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code 31
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From: Clinton, MD
code 31
My 1988 F150, 4.9L 2WD, stick, fuel injection, has been failing the emissions test with high NO2's for the past four years.(DYNO TEST) This year same problem....scan code 31 comes up. I have changed EGR valve and solenoid, vacuum lines, air filter, oil, cap & rotor, 8mm wires, MSD 6A, plugs...etc. Still get code 31..even changed ECU today, still code 31. Haven't been back to test station yet. Any ideas??
Thanks.
email <st1:PersonName w:st="on">tranthac2000@yahoo.com</st1:PersonName>
Thanks.
email <st1:PersonName w:st="on">tranthac2000@yahoo.com</st1:PersonName>
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Joined: Oct 2005
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From: Berlin, CT USA
I am not to familar with the codes and the memory but u could try to reset the computer i think it can be done by disconnection the battery terminal, dont hold me to this i am not sure. Hope you have better luck then me
Elder User
Joined: May 2006
Posts: 623
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From: Mississauga,Ont.,Canada
Code 31 says that the evp circuit is below the minimum voltage. The BR/LG wire is evp signal, O/W is vehicle reference(VREF) and BL/W is the signal return(SIG RTN). Check for voltage with a digital voltmeter . With the harness disconnected , key on , check for voltage between VREF and SIG RTN. Should be between 4-6 volts dc preferbly 5 volts. If you are up to it you can create a code 35 which is the opposite of 31 , evp circuit above maximum voltage.Place a jumper between evp signal and VREF. Run the self test . If you generate a code 35 the wiring is ok.What kind of numbers are you getting for your nox and what is the limit.
Last edited by mississauga; Aug 17, 2006 at 09:40 PM.
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From: Clinton, MD
More codes
Originally Posted by ctran
My 1988 F150, 4.9L 2WD, stick, fuel injection, has been failing the emissions test with high NO2's for the past four years.(DYNO TEST) This year same problem....scan code 31 comes up. I have changed EGR valve and solenoid, vacuum lines, air filter, oil, cap & rotor, 8mm wires, MSD 6A, plugs...etc. Still get code 31..even changed ECU today, still code 31. Haven't been back to test station yet. Any ideas??
Thanks.
email <st1
ersonname w:st="on">tranthac2000@yahoo.com</st1ersonname>
Thanks.
email <st1
ersonname w:st="on">tranthac2000@yahoo.com</st1ersonname>After a few days I am getting codes 32 and 41 after clearing code 31?
32-EGR pressure feedback fault.
41-(HEGO) HO2S sensor voltage low/system lean
Tom Wong, haven't replaced my CAT yet.
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From: youngstown ohio
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From: Clinton, MD
How does removing your EGR valve effect your emmissions? What other problems (if any) does this cause?
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From: The dark carnival
A code 31 is either the EGR position sensor, wiring to the sensor, the EGR valve itself, the EEC-IV or a damaged vacuum reservoir or canister.
As far as what will happen if the EGR valve is removed or blocked off...
NOx emissions will increase
Spark knock will take place
An increase in combustion temp. will take place
As far as what will happen if the EGR valve is removed or blocked off...
NOx emissions will increase
Spark knock will take place
An increase in combustion temp. will take place
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From: Clinton, MD
Kimble's Complete Auto Repair in Clinton, MD is trying to RIP me off
Kimble's , is trying to rip me off.....I took my 88 F150 to them to have the oil pan gasket replaced. (typical Ford problem 4.9L) They claimed they had replaced the gasket, but there is so much oil they think it's coming from some where else???? I picked up the truck, still saw a little oil leak. It was dark and it rained all day Friday. Saturday I finally got a chance to get under there, There was oil every where.......the pan had not even been wiped off..oil leaking from the same place on the gasket. Took it back today after I had washed the underside of the truck and verified that the gasket had not been touched. Cost me over $550.00. Waiting on results.
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