jim

i got a 93 taurus, v-6 with trouble codes that were scanned at auto
zone.. the codes are 25, knock sensor
34 EVP(EGR Valve position)voltage out of range
51 ECT (Engine Coolant Temperature) sensor
signal voltage too high

the check engine light would come on an go off all the time.......
start car and drive off and about a block away and it would come on..
then go off and back on and then stay on.... i learned that the Taruus
GL that i have does not have a Knock sensor so i ruled out the code 25
as being the culprit... i then checked looked at the ECT and did not
knwo how to check it so i went to the EVP and did not know how to check
it.. i then went to the air filter and it looked brand new.. remembered
that i changed it about one month ago... i then removed the MAF sensor
and cleaned the two little wires/sensors in there with some windex on
Q-tips and scratched up the electical connection on it to make sure it
was making good contact to the harness... put it back in and drove
around and the car seemed to run alot better. before it was killing when
starting up and seems to have a shake in the engine like when you have a
car thats flooding with the old carbs. so far two days now and the
check engine light did not return.... could this be the fix for this
car??? three other codes and noting mentioned about the MAF, but
cleaning it corrected the problem... or did it????? thenks for a
reply...
well i found out that the ck eng. light came back on.. i checked the ECT
by putting the ohm meter on it when the engine was cold and then when
warm and it seemed to be OK... nothing when cold and movement on the
needle when hot.... then took out the EVP and brought it to auto zone
and they put pressure on the valve and cheed it with the meter after
putting six volts on it and they told me it was OK... i later returned
home and pulled off the EGR and blew into one side and it was closed(no
air flow from 1/2 pipe hole)... i then put vacuum on the egr and the
valve was now open.. it seemed to be OK... i checked the small hose on
the EVP and it seemed to be alright, no blocked.. the passage that the
EVP small tube that went to the exhaut manifold seemed to not be
blocked.. the tubing from the EGR seemed to be clear also...
any suggestions????? one more question: when is the vacuum line to
the EGR valve suppose to have vacuum to it???? i think the vacuum is
whats suppose to open the EGR valve.. if i remmber correctly the intake
manifold should be high in vacuum when at idle, then go off when you
give it gas, and then come back on when the car is coasting along??? at
least that is the way it was back in the old days of the vacuum operated
windshield wipers... any suggestions???? thanks for a reply.....