Today the ceck engine light was flickering on and off. Finally after awhile it stayed on. I got home tonight and ran the codes and came up with these lovely little ones:

KOEO: 35-PFE or EVP circuit above the maximum limit of 4.81 volts.
CM: 34- PFE or EVP circuit has intermittently failed above the closed limit of 0.67 volts

KOER: 41-No HEGO switching detected always lean (right side).
35- PFE or EVP circuit above the maximum limit of 4.81 volts.

The truck was warm when the test was ran because I just got home from towing a car and got out and grounded the wire and ran the tests.

Most of the codes have to do with the EGR. But im not sure on what to attack here. The TPS is fairly new and it is getting vacuum. Where should I begin here??

 

Sounds like maybe you lost the ground to the EVP sensor (bad contact in plug or open wire).

 

Haha i just reread my thread and laughed. EVP is definatly not the same as EVR. LOL has nothing to do with the EGR or TPS. Oh well. Thts what you get for being in a hurry.

Ill check out the connections and what not tomorrow to see what had happened and make sure its nothing stupid.

 

The EVP does tell the computer the position of the EGR valve.
EVP: EGR Valve Position sensor or its signal circuit.

 

right well iwas thinking that the EVR was the TPS for some reason lastnight. it was late and i wasnt thinking. i wiggled the connectors a bit and the light went off. but wat about the code 41? is this meaning i need a new O2?

 

Maybe but here the things that would cause it:

Possible Causes:
-- Fuel injectors
-- HEGO sensor
-- Thermactor
-- PCV
-- Vacuum
-- CANP
-- MAP sensor

 

Maybe but here the things that would cause it:

Possible Causes:
-- Fuel injectors-new
-- HEGO sensor- not sure about this one. Location and how to test?
-- Thermactor- not equipped
-- PCV- new valve and elbow
-- Vacuum- shouldnt be a problem. Will check everything over again.
-- CANP- not sure about this one. Location and how to test
-- MAP sensor- how would you know if this went bad?

 

subford left "fuel pressure" off of the list, but you would probably notice a severe lack of power by the time it got low enough to set a code, but it might be worth checking.

Also, by vacuum he means that you should be checking the entire intake system, PCV system, and vacuum lines for leaks.

The hego sensor is in the exhast pipe, usually down under the cab on the F250s. It is small, about the size of an elongated "C" cell battery, and has flats for a 7/8" wrench. There isn't a really easy way for you to test it, but if it has more that 60k miles I would highly recommend you just replace it. The PCM uses this sensor to adjust fuel mixture and they can cause the engine to run rich when they get older by telling the PCM that the engine is running lean all of the time.

CANP = "CANister Purge solenoid." It is what empties the charcoal canister of fuel vapors when the engine is running. If it sticks open, it can make the engine run lean. Trace the small vacuum line attached to the throttle body that runs toward the passenger fender. Along the line you will find a small solenoid, about the size of a "C" cell battery again, with a connector on it with two wires. Check this line for leaks and make sure there is no vacuum on the fender side of the valve with the connector disconnected and the engine running.

The upper intake gaskets are very prone to leaking on these engines. I would very carefully use brake cleaner with a straw on the nozzle to spray around the gasket area between the upper and lower intake while the engine is running and listen for a change in engine RPM. You must use flammable type brake cleaner, and obviously use caution spraying it around the ignition parts.

Jay

 

Fuel pressure is constantly monitored and all vac lines were replaced along with all new gaskets on the motor when it went in. I will replace the old O2 as I know it is the origional one from 89. We will see what happens here.