code 31

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code 31

October 31, 2007, 07:55:38 AM

ran codes last night for the first time, KOEO ran code 31, KOER ran code 31,,,something about EVP voltage not right???? what the he!! is the EVP and how to fix or do i even need to worry about it?

Thanks guys
Joe

code 31

Reply #1 – October 31, 2007, 08:06:26 AM

EGR still hooked up on your car?

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Reply #2 – October 31, 2007, 08:56:20 AM

what year make and model, and engine????????? evap is all emission stuff, for example evap is the gas vapors from your fuel system beeing released to the atmosphere. your tank builds pressure and at certain times and speeds the evap system does it's job.

code 31

Reply #3 – October 31, 2007, 08:58:28 AM

EVP = EGR Valve Position sensor

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Reply #4 – October 31, 2007, 10:36:58 AM

Chuck W--yes, EGR and all smog(new smog pump) is still hooked up(no cats), could my egr position sensor be bad?

screaming306-- make and model, engine specs are in my sig

thanks

code 31

Reply #5 – October 31, 2007, 11:28:14 AM

Quote from: flipnbird;185570

Chuck W--yes, EGR and all smog(new smog pump) is still hooked up(no cats), could my egr position sensor be bad?

Yes, it's possible. It's bolted to the EGR valve. I'm sure there is a way to test it, I don't have that info in front of me here at work though.

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Reply #6 – October 31, 2007, 01:14:09 PM

whenever you get a chance, maybe let me know how to check it, if there is a way.... no big hurry!
Thanks again

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Reply #7 – October 31, 2007, 10:17:14 PM

guys, checking the evp sensor is in my DIY link. just follow the instructions.,,, when you test it and find out its good, its time to get out your handy dandy vac hose and suck on the egr and see if it holds suction to your tongue for a good long while. If it does, that tells you the diaphram is not ruptured.

basic construction of the egr and operation...............

vac suction is applied to the diaphram
diaphram has a metal center disc
center disk touches a rod that goes up into the EVP sensor.
Evp sensor moves in and out based on the postition of the diaphram
the evp can be removed and resistance check can be taken from the pins on the sensor.,,its just a variable resistor.
I just posted a schematic about this on another thread for a guy with a 3.8 engine having trouble.

Just do a resistance check on the evp, and if there are no open spots and the resistance smoothly transitions, check for carbon buildup down in the egr ports on the intake.

from my DIY LINK>>>>>>>>>>>>>>.

EGR test and EVP sensor test
apply vac pres to egr vac line fitting.
if it holds the diaphram for a long time,, the diaphram is good
remove carbon buildup on egr base as well as egr base plate assy for 3.8l engines

EVP test (egr sensor)
wire id...
EEC PIN 26 "VREF" orange/white (parallels off to map)
EEC PIN 27 "EVP SIGNAL" brown/light green
EEC PIN 46 "SIG Return" black/white (parallels off to self test conn)

disconnect vac line
disconnect elec conn
hook ohm meter up to the VREF adn EVP Sig contacts
hook up vac guage or apply vac to egr
ohm meter should start out at about 5.5k ohms.
as vac is increased to max, resistance should bottom out to no less than 100ohms.

key on, engine off
cap off vac fitting on evp sensor
measure for 4 to 6 volts dc between VREF and SIGNAL RETURN (ground)

code 31

Reply #8 – October 31, 2007, 10:24:43 PM

Quote from: screaming306;185557

what year make and model, and engine????????? evap is all emission stuff, for example evap is the gas vapors from your fuel system beeing released to the atmosphere. your tank builds pressure and at certain times and speeds the evap system does it's job.

??????????????????
the question isnt that complicated but i guess it could be depending on what you look at